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2001 Volume 18 Issue 5
2001, 18(5): 259-266
Abstract:
This review covers recent advances in fabrication of nanomaterials in polymer solutions with emphasis on using the self-assembled amphiphilic block copolymers in solution to fabricate organic/inorganic composites with nanoscale modifications. The phase behavior of block copolymers in water and the use of templates to form ordered nanostructures are reviewed in detail. Modern physical techniques for nanoscale characterization are also introduced. The authors suggested that this approach should provide new routes to create materials with interesting morphologies for many different applications.
This review covers recent advances in fabrication of nanomaterials in polymer solutions with emphasis on using the self-assembled amphiphilic block copolymers in solution to fabricate organic/inorganic composites with nanoscale modifications. The phase behavior of block copolymers in water and the use of templates to form ordered nanostructures are reviewed in detail. Modern physical techniques for nanoscale characterization are also introduced. The authors suggested that this approach should provide new routes to create materials with interesting morphologies for many different applications.
2001, 18(5): 267-274
Abstract:
Blends of polypropylene (PP) and low density polyethylene (LDPE) have been crystallized to form open structures("cluster spherulites") where the droplets of the minority PP are bridged by PP lamellae which have grown in the LDPE-rich matrix. These are studied by permanganic etching followed by electron and optical microscopies. Two similar PP types are compared, one synthesized with Ziegler-Natta catalyst and one with metallocene catalyst. The metallocene-catalysed material crystallized much more slowly due to the presence of regio defects in the chains, even though the overall concentration of tacticity defects in the Ziegler-Natta material is much higher. A mechanism involving reversal of helical direction at the regio defect interfering with the regular chain packing in the crystal is suggested. Growth of "cluster spherulites" is faster in regions where low molecular weight material is concentrated. It is slower where droplets are larger, and this is attributed to competition between PP lamellar growth in the matrix and diffusion of PP to already crystallized droplets.
Blends of polypropylene (PP) and low density polyethylene (LDPE) have been crystallized to form open structures("cluster spherulites") where the droplets of the minority PP are bridged by PP lamellae which have grown in the LDPE-rich matrix. These are studied by permanganic etching followed by electron and optical microscopies. Two similar PP types are compared, one synthesized with Ziegler-Natta catalyst and one with metallocene catalyst. The metallocene-catalysed material crystallized much more slowly due to the presence of regio defects in the chains, even though the overall concentration of tacticity defects in the Ziegler-Natta material is much higher. A mechanism involving reversal of helical direction at the regio defect interfering with the regular chain packing in the crystal is suggested. Growth of "cluster spherulites" is faster in regions where low molecular weight material is concentrated. It is slower where droplets are larger, and this is attributed to competition between PP lamellar growth in the matrix and diffusion of PP to already crystallized droplets.
2001, 18(5): 275-279
Abstract:
Particulate composites based on isotactic polypropylene (iPP) and titanium dioxide(TiO2) have been prepared and their morphology and thermal behavior investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Tensile tests were performed to assess the influence of TiO2 on the mechanical properties of the iPP.
Particulate composites based on isotactic polypropylene (iPP) and titanium dioxide(TiO2) have been prepared and their morphology and thermal behavior investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Tensile tests were performed to assess the influence of TiO2 on the mechanical properties of the iPP.
2001, 18(5): 280-288
Abstract:
Structure and morphology development during isothermal crystallization and subsequent melting of syndiotactic polypropylene (sPP) was studied by time-resolved simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) methods with synchrotron radiation and differential scanning calorimetry (DSC). The time and temperature dependent parameters such as long period, L, crystal lamellar thickness, lc, amorphous layer thickness, la, scattering invariant, Q, crystallinity, Xc, lateral crystal sizes, L200 and L020, and unit cell parameters a and b were extracted from SAXS and WAXD profiles. Decreasing long period and crystal thickness indicate that thinner secondary crystal lamellae are formed. The decreases in unit cell parameters a and b during isothermal crystallization process suggest that crystal perfection takes place. The changes in the morphological parameters (the invariant, Q, crystallinity, Xc, long period, L, and the crystal thickness, lc) during subsequent melting were found to follow a two-stage melting process, corresponding to the dual endotherm behavior in the DSC scan. We conclude that the dual melting peaks are due to the melting of secondary and primary lamellae(first peak) and the subsequent recrystallization-melting process (second peak). Additional minor endothermic peak located at the lowest temperature was also detected and might be related to melting of secondary, thinner and defective lamellae. WAXD showed that during melting, thermal expansion was greater along the b axis than that along the a axis.
Structure and morphology development during isothermal crystallization and subsequent melting of syndiotactic polypropylene (sPP) was studied by time-resolved simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) methods with synchrotron radiation and differential scanning calorimetry (DSC). The time and temperature dependent parameters such as long period, L, crystal lamellar thickness, lc, amorphous layer thickness, la, scattering invariant, Q, crystallinity, Xc, lateral crystal sizes, L200 and L020, and unit cell parameters a and b were extracted from SAXS and WAXD profiles. Decreasing long period and crystal thickness indicate that thinner secondary crystal lamellae are formed. The decreases in unit cell parameters a and b during isothermal crystallization process suggest that crystal perfection takes place. The changes in the morphological parameters (the invariant, Q, crystallinity, Xc, long period, L, and the crystal thickness, lc) during subsequent melting were found to follow a two-stage melting process, corresponding to the dual endotherm behavior in the DSC scan. We conclude that the dual melting peaks are due to the melting of secondary and primary lamellae(first peak) and the subsequent recrystallization-melting process (second peak). Additional minor endothermic peak located at the lowest temperature was also detected and might be related to melting of secondary, thinner and defective lamellae. WAXD showed that during melting, thermal expansion was greater along the b axis than that along the a axis.
2001, 18(5): 289-295
Abstract:
A review of methods for the anionic synthesis of well-defined, amine-functionalized polymers using imines as functionalizing agents is provided. The disparate results in the literature regarding functionalizations with N-(benzylidene)trimethylsilylamine to form primary amine functionalized polymers are discussed; the efficiency of functionalization depends on the molecular weight of the polymeric organolithium (PLi). Efficient functionalizations are observed for PLi with Mn>10 000 g/mol. The poor functionalization yields using ketimines with enolizable hydrogens is explained. The use of N-trimethylsilyldiphenylcarbimide as a quantitative primary amine functionalizing reagent is described. Recent results on the anionic synthesis of secondary amine-functionalized polymers using N-(benzylidene)methylamine as the functionalization agent are presented.
A review of methods for the anionic synthesis of well-defined, amine-functionalized polymers using imines as functionalizing agents is provided. The disparate results in the literature regarding functionalizations with N-(benzylidene)trimethylsilylamine to form primary amine functionalized polymers are discussed; the efficiency of functionalization depends on the molecular weight of the polymeric organolithium (PLi). Efficient functionalizations are observed for PLi with Mn>10 000 g/mol. The poor functionalization yields using ketimines with enolizable hydrogens is explained. The use of N-trimethylsilyldiphenylcarbimide as a quantitative primary amine functionalizing reagent is described. Recent results on the anionic synthesis of secondary amine-functionalized polymers using N-(benzylidene)methylamine as the functionalization agent are presented.
2001, 18(5): 296-300
Abstract:
New thermoplastic norbornene polymers containing ester groups were prepared by vinylic polymerization of norbornene-carboxylic acid esters by Pd(Ⅱ)-based catalysts. The monomers were obtained by Diels-Alder reaction of cyclopentadiene with acrylic acid esters (methyl and butyl) as mixtures of endo/exo (ratio 40/60)-isomers and were converted to polymers in 60%~70% conversion. The endo-isomer was less reactive than the exo-isomer. To obtain higher molecular weight the more reactive pure exo-isomer was prepared and polymerized with the Pd(Ⅱ)-catalysts, tetrakis(acetonitrile) Pd(Ⅱ) bis(tetrafluoroborate) and (Z3-allyl) Pd(Ⅱ)SbF6, in high conversion. These polymers showed high glass transition temperatures, high transparency and good solubility in common solvents.
New thermoplastic norbornene polymers containing ester groups were prepared by vinylic polymerization of norbornene-carboxylic acid esters by Pd(Ⅱ)-based catalysts. The monomers were obtained by Diels-Alder reaction of cyclopentadiene with acrylic acid esters (methyl and butyl) as mixtures of endo/exo (ratio 40/60)-isomers and were converted to polymers in 60%~70% conversion. The endo-isomer was less reactive than the exo-isomer. To obtain higher molecular weight the more reactive pure exo-isomer was prepared and polymerized with the Pd(Ⅱ)-catalysts, tetrakis(acetonitrile) Pd(Ⅱ) bis(tetrafluoroborate) and (Z3-allyl) Pd(Ⅱ)SbF6, in high conversion. These polymers showed high glass transition temperatures, high transparency and good solubility in common solvents.
2001, 18(5): 301-309
Abstract:
Poly (ethylene-co-chlorotrifluoroethylene) with a 1:1 molar ratio of ethylene and chlorotrifluoroethylene in composition, PECTFE, is a statistically alternating copolymer widely used in cable coating industry. PECTFE has been commonly characterized as a semicrystalline polymer with crystals melting at 238℃. Differential scanning calorimetry, thermal mechanical analysis and dynamic mechanical analysis indicated that PECTFE undergoes a reversible solid-solid transition during cooling and heating in the temperature range between 100℃ and 200℃. Based on detailed structural analysis via wide angle X-ray diffraction and electron diffraction techniques, we proposed that PECTFE possesses a hexagonal phase above 200℃(a=0.60 nm, c=0.49 nm) and an orthorhombic phase (a=0.99 nm, b=0.57 nm, c=0.49 nm) at room temperature.
Poly (ethylene-co-chlorotrifluoroethylene) with a 1:1 molar ratio of ethylene and chlorotrifluoroethylene in composition, PECTFE, is a statistically alternating copolymer widely used in cable coating industry. PECTFE has been commonly characterized as a semicrystalline polymer with crystals melting at 238℃. Differential scanning calorimetry, thermal mechanical analysis and dynamic mechanical analysis indicated that PECTFE undergoes a reversible solid-solid transition during cooling and heating in the temperature range between 100℃ and 200℃. Based on detailed structural analysis via wide angle X-ray diffraction and electron diffraction techniques, we proposed that PECTFE possesses a hexagonal phase above 200℃(a=0.60 nm, c=0.49 nm) and an orthorhombic phase (a=0.99 nm, b=0.57 nm, c=0.49 nm) at room temperature.
2001, 18(5): 310-315
Abstract:
In the preparation of catalyst for propylene polymerization, the Mg(OEt)2 support was activated with ethanol/CO2 system followed by solidification, and treated with TiCl4 in the presence of ethylbenzoate as an internal donor (ID). The chemical compositions of the activated support and the prepared catalyst were examined in detail. During the dissolution of Mg(OEt)2 support in ethanol medium with CO2 bubbling, the structure of support changed to magnesium hydrocarbyl carbonate, (CH3CH2O)2-x Mg(O(C=O)OCH2CH3)x (x=1,2). The content of carbonated CO2 in the activated support was dependent on the heat treatment in the solidification of support. In the preparation procedure of polymerization catalyst, the activated support was treated with TiCl4 so that the structure of support was converted to MgCl2 with the incorporation of ID. The polymerization behavior of the prepared catalyst was also studied in the presence of phenyltriethoxysilane as an external donor.
In the preparation of catalyst for propylene polymerization, the Mg(OEt)2 support was activated with ethanol/CO2 system followed by solidification, and treated with TiCl4 in the presence of ethylbenzoate as an internal donor (ID). The chemical compositions of the activated support and the prepared catalyst were examined in detail. During the dissolution of Mg(OEt)2 support in ethanol medium with CO2 bubbling, the structure of support changed to magnesium hydrocarbyl carbonate, (CH3CH2O)2-x Mg(O(C=O)OCH2CH3)x (x=1,2). The content of carbonated CO2 in the activated support was dependent on the heat treatment in the solidification of support. In the preparation procedure of polymerization catalyst, the activated support was treated with TiCl4 so that the structure of support was converted to MgCl2 with the incorporation of ID. The polymerization behavior of the prepared catalyst was also studied in the presence of phenyltriethoxysilane as an external donor.
2001, 18(5): 316-321
Abstract:
Incorporation of synthetic heme (FeP) into recombinant human serum albumin (rHSA) provides an artificial hemoprotein (rHSA-FeP) which can bind and release oxygen reversibly under physiological conditions(in aqueous media, pH 7.3, 37℃) like hemoglobin (Hb) and myoglobin. An rHSA host absorbs maximally eight FeP molecules, and the solution properties are almost identical to those of rHSA itself. The second-order structure and surface charge distribution of rHSA were always constant independent of the binding numbers of FeP. Its O2-binding ability satisfies the initial clinical requirements for red cell substitute. Although the NO-binding affinity is 8-fold high compared to the Hb's, administration of this fluid into rats showed negligible change in the blood pressure. Physiological responses to exchange transfusion with this rHSA-FeP into anaesthetized rats have also been evaluated.
Incorporation of synthetic heme (FeP) into recombinant human serum albumin (rHSA) provides an artificial hemoprotein (rHSA-FeP) which can bind and release oxygen reversibly under physiological conditions(in aqueous media, pH 7.3, 37℃) like hemoglobin (Hb) and myoglobin. An rHSA host absorbs maximally eight FeP molecules, and the solution properties are almost identical to those of rHSA itself. The second-order structure and surface charge distribution of rHSA were always constant independent of the binding numbers of FeP. Its O2-binding ability satisfies the initial clinical requirements for red cell substitute. Although the NO-binding affinity is 8-fold high compared to the Hb's, administration of this fluid into rats showed negligible change in the blood pressure. Physiological responses to exchange transfusion with this rHSA-FeP into anaesthetized rats have also been evaluated.
2001, 18(5): 322-329
Abstract:
Treatment of 1,3-di-t-butylcyclopentadiene with rhodium trichloride in EtOH leads to the formation of binuclear half-sandwich complex [Cpt RhCl(_-Cl)]2 (1) (Cpt=Z5-tBu2C5H3) which reacts with trimethylphosphine to give Cpt Rh(PMe3)Cl2 (2) in high yield. 2 reacts with ammonium polysulfide, (NH4)2Sx to give cyclooligosulfido half-sandwich complexes Cpt Rh(PMe3)(Sn)(n=4(4a),6(4b)). Desulfurization of 4b by excess PPh3 results in cyclotetrasulfido product 4a, while 4a takes up sulfur from polysulfide to convert cyclohexasulfido product 4b. The reaction of 2 with Et4NI gives diiodide complex 3 which is determined by single crystal X-ray crystallographic analysis.
Treatment of 1,3-di-t-butylcyclopentadiene with rhodium trichloride in EtOH leads to the formation of binuclear half-sandwich complex [Cpt RhCl(_-Cl)]2 (1) (Cpt=Z5-tBu2C5H3) which reacts with trimethylphosphine to give Cpt Rh(PMe3)Cl2 (2) in high yield. 2 reacts with ammonium polysulfide, (NH4)2Sx to give cyclooligosulfido half-sandwich complexes Cpt Rh(PMe3)(Sn)(n=4(4a),6(4b)). Desulfurization of 4b by excess PPh3 results in cyclotetrasulfido product 4a, while 4a takes up sulfur from polysulfide to convert cyclohexasulfido product 4b. The reaction of 2 with Et4NI gives diiodide complex 3 which is determined by single crystal X-ray crystallographic analysis.
2001, 18(5): 330-335
Abstract:
The reaction of LnCl3 with two equivalents of 2,4-dimethyl-pentadienyl potassium affords (2,4-C7H11)3Ln(Ln=Dy,Er). The compound (2,4-C7H11)3Dy(1), crystallized from a mixed solvent of hexane and THF has a triclinic space group Pl with a=1.270 2(2) nm, b=1.290 8(2) nm, c=0.847 9(2) nm, T=91.48(2)°, U=108.41(2)°, V=118.41(2)°, Z=2. The compound (2,4-C7H11)3Er(2) was crystallized from toluene in triclinic P1 with a=0.909 5(3) nm,b=1.407 2(3) nm, c=1.657 7(6) nm, T=106.66(2)°, U=93.77(3)°, V=89.76(2)°, Z=4. Both structures were solved by using direct methods and refined by block-matrix least-squares to final values of R=0.039 for 1 and R=0.067 for 2. A comparison of some significant structural parameters in (2,4-C7H11)3Ln(Ln=Dy,Er) with those from other analogues (2,4-C7H11)3Ln(Ln=Nd,Gd) was made.
The reaction of LnCl3 with two equivalents of 2,4-dimethyl-pentadienyl potassium affords (2,4-C7H11)3Ln(Ln=Dy,Er). The compound (2,4-C7H11)3Dy(1), crystallized from a mixed solvent of hexane and THF has a triclinic space group Pl with a=1.270 2(2) nm, b=1.290 8(2) nm, c=0.847 9(2) nm, T=91.48(2)°, U=108.41(2)°, V=118.41(2)°, Z=2. The compound (2,4-C7H11)3Er(2) was crystallized from toluene in triclinic P1 with a=0.909 5(3) nm,b=1.407 2(3) nm, c=1.657 7(6) nm, T=106.66(2)°, U=93.77(3)°, V=89.76(2)°, Z=4. Both structures were solved by using direct methods and refined by block-matrix least-squares to final values of R=0.039 for 1 and R=0.067 for 2. A comparison of some significant structural parameters in (2,4-C7H11)3Ln(Ln=Dy,Er) with those from other analogues (2,4-C7H11)3Ln(Ln=Nd,Gd) was made.
2001, 18(5): 336-341
Abstract:
Self-assembled nanostructure is a prevalent phrase in chemistry in recent years. Block copolymers in a selective solvent can be self-assembled to micelles. Polymer micelles may eventually prove to have important technological applications. We have studied interpolymer complexation through specific interactions for years. However, the complexation usually does not lead to well-defined structures. Our new approach is: when polymer A is dissolved in a good solvent and added to a solution containing polymer B in a nonsolvent for A, the precipitation of A can be prevented due to the specific interaction between A and B, and instead, micelles with A core and B corona are formed. Similarly, it is also possible to prepare "graft copolymer" between A and B in a common solvent via hydrogen bonding first, then mix it with a selective solvent to form A-B micelles. This kind of micelle differs from the conventional block copolymer micelles, in which the corona and the core are chemically bonded. This paper summarizes our major recent results on this new approach to several different kinds of systems, either in organic or in aqueous media.
Self-assembled nanostructure is a prevalent phrase in chemistry in recent years. Block copolymers in a selective solvent can be self-assembled to micelles. Polymer micelles may eventually prove to have important technological applications. We have studied interpolymer complexation through specific interactions for years. However, the complexation usually does not lead to well-defined structures. Our new approach is: when polymer A is dissolved in a good solvent and added to a solution containing polymer B in a nonsolvent for A, the precipitation of A can be prevented due to the specific interaction between A and B, and instead, micelles with A core and B corona are formed. Similarly, it is also possible to prepare "graft copolymer" between A and B in a common solvent via hydrogen bonding first, then mix it with a selective solvent to form A-B micelles. This kind of micelle differs from the conventional block copolymer micelles, in which the corona and the core are chemically bonded. This paper summarizes our major recent results on this new approach to several different kinds of systems, either in organic or in aqueous media.
2001, 18(5): 342-346
Abstract:
Optical resins as important members of polymeric optical materials have been widely used in optical fields as substitutes for inorganic glasses. The research on the optical resins with high refractive index is still the main trend of resin lens development. In this paper, the preparation methods of high refractive index optical resins are summarized based on the molecule design principle. The research developments of two-type novel optical resins materials-epoxy and episulfide-type optical resins including preparation methods, relations between structure and properties are reviewed.
Optical resins as important members of polymeric optical materials have been widely used in optical fields as substitutes for inorganic glasses. The research on the optical resins with high refractive index is still the main trend of resin lens development. In this paper, the preparation methods of high refractive index optical resins are summarized based on the molecule design principle. The research developments of two-type novel optical resins materials-epoxy and episulfide-type optical resins including preparation methods, relations between structure and properties are reviewed.
2001, 18(5): 347-350
Abstract:
The recent application researches of poly(propylene carbonate) synthesized from propylene oxide and carbon dioxide are reviewed, including adhesives which can be completely decomposed at relative low temperatures, solid electrolytes, polyols used for polyurethane synthesis, photoresists, barrier materials with low gas permeability, flexibilizers for epoxide resins and plasticizers for PVC based on the low Tg of PPC. The researches on the blends of carbon dioxide copolymer with rubbers, e.g. nitrile rubber, styrene-butadiene rubber, ternary ethylenepropylene rubber and nature rubber including their mechanical property and structure are summarized in more detail.
The recent application researches of poly(propylene carbonate) synthesized from propylene oxide and carbon dioxide are reviewed, including adhesives which can be completely decomposed at relative low temperatures, solid electrolytes, polyols used for polyurethane synthesis, photoresists, barrier materials with low gas permeability, flexibilizers for epoxide resins and plasticizers for PVC based on the low Tg of PPC. The researches on the blends of carbon dioxide copolymer with rubbers, e.g. nitrile rubber, styrene-butadiene rubber, ternary ethylenepropylene rubber and nature rubber including their mechanical property and structure are summarized in more detail.
2001, 18(5): 351-356
Abstract:
Researches on clay/polyolefin nanocomposites have been reviewed. Both the thermodynamic and kinetic analyses for the formation process of clay/polyolefin nanocomposites are elucidated. The preparation and characterization of the structures and properties of clay/PE, clay/PP nanocomposites are elaborated with emphasis on the in situ polymerization intercalation compounding.
Researches on clay/polyolefin nanocomposites have been reviewed. Both the thermodynamic and kinetic analyses for the formation process of clay/polyolefin nanocomposites are elucidated. The preparation and characterization of the structures and properties of clay/PE, clay/PP nanocomposites are elaborated with emphasis on the in situ polymerization intercalation compounding.
2001, 18(5): 357-359
Abstract:
A number of organotin, cyclopentadienyltitanium, cyclopentadienylzirconium and organophosphoryl substituted polyoxometalates are reported in relation of their antitumor activity against SSMC-7721 and Hela human tumor cells. The cyclopentadienyltitanium polyoxometalates showed higher activity than other compounds with the same polyanions. CoW11CpTi was found to have higher antitumor activity and low toxicity as showed in vivo tests. It is also observed that the order of the antitumor activity of complexes is in relation with the order of the redox behavior of the polyanions.
A number of organotin, cyclopentadienyltitanium, cyclopentadienylzirconium and organophosphoryl substituted polyoxometalates are reported in relation of their antitumor activity against SSMC-7721 and Hela human tumor cells. The cyclopentadienyltitanium polyoxometalates showed higher activity than other compounds with the same polyanions. CoW11CpTi was found to have higher antitumor activity and low toxicity as showed in vivo tests. It is also observed that the order of the antitumor activity of complexes is in relation with the order of the redox behavior of the polyanions.
2001, 18(5): 360-364
Abstract:
Recent achievements in ethylene oligomerization by using transition metal complexes as catalysts are reviewed with emphases on the description of novel catalyst systems. The relationship between the behavior of catalysts in oligomerization and polymerization has been discussed. The oligomerization and polymerization of ethylene have readily identifiable mechanistic feature, difference is the rate of insertion and U-H elimination. M4+ (M=Ti,Zr) complexes mainly catalyze ethylene oligomerization, and M3+ (M=Ti,Zr) complexes catalyze polymerization. Altering the cocatalyst composition of group Ⅳ B metallocene catalyst systems and reaction conditions leads to oligomerization of ethylene. Group Ⅷ complexes with small volume of ligands favor the U-H elimination and oligomerization.
Recent achievements in ethylene oligomerization by using transition metal complexes as catalysts are reviewed with emphases on the description of novel catalyst systems. The relationship between the behavior of catalysts in oligomerization and polymerization has been discussed. The oligomerization and polymerization of ethylene have readily identifiable mechanistic feature, difference is the rate of insertion and U-H elimination. M4+ (M=Ti,Zr) complexes mainly catalyze ethylene oligomerization, and M3+ (M=Ti,Zr) complexes catalyze polymerization. Altering the cocatalyst composition of group Ⅳ B metallocene catalyst systems and reaction conditions leads to oligomerization of ethylene. Group Ⅷ complexes with small volume of ligands favor the U-H elimination and oligomerization.
2001, 18(5): 365-369
Abstract:
Nanospheres with entrapped insulin were prepared by a solvent extraction method with a series of copolymers of DL-lactide(PLA) and polyethylene glycol (PEG)(INS/PELA) where the PEG is in different molecular weight and content. The nanospheres as TEM shows have a smooth and spherical surface sized between 100~200 nm. The amount of insulin in nanospheres and the entrapment ratio achieved 17.5% and 87.6%, respectively. In vitro studies indicated that release of insulin from nanospheres could last over 10 days.
Nanospheres with entrapped insulin were prepared by a solvent extraction method with a series of copolymers of DL-lactide(PLA) and polyethylene glycol (PEG)(INS/PELA) where the PEG is in different molecular weight and content. The nanospheres as TEM shows have a smooth and spherical surface sized between 100~200 nm. The amount of insulin in nanospheres and the entrapment ratio achieved 17.5% and 87.6%, respectively. In vitro studies indicated that release of insulin from nanospheres could last over 10 days.
2001, 18(5): 370-372
Abstract:
Atom transfer radical polymerization (ATRP) of glycidyl methacrylate (GMA) at room temperature was carried out in a methylethyl ketone/1-propanol (in 7/3 volume ratio) solution, initiated and catalyzed by ethyl 2-bromopropionate(BRA)/CuCl/2,2'-bipyridine(BPY). Polymer of GMA with planned molecular weight and narrow molecular weight distribution was obtained. In case of bulk polymerization with the same initiator and catalyst the molecular weight of the polymer obtained was 1.5~2.1 times greater than that of the above one. By using 1-phenylethyl chloride(PECl)/CuCl/BPY as catalyst controlled ATRP of GMA has failed whether it was in bulk or in solution.
Atom transfer radical polymerization (ATRP) of glycidyl methacrylate (GMA) at room temperature was carried out in a methylethyl ketone/1-propanol (in 7/3 volume ratio) solution, initiated and catalyzed by ethyl 2-bromopropionate(BRA)/CuCl/2,2'-bipyridine(BPY). Polymer of GMA with planned molecular weight and narrow molecular weight distribution was obtained. In case of bulk polymerization with the same initiator and catalyst the molecular weight of the polymer obtained was 1.5~2.1 times greater than that of the above one. By using 1-phenylethyl chloride(PECl)/CuCl/BPY as catalyst controlled ATRP of GMA has failed whether it was in bulk or in solution.
2001, 18(5): 373-376
Abstract:
The block copolymer of isoprene(Ip) and 1,2-epoxyhexane (HEO) was synthesized by rare earth coordination catalyst, [Nd(P204)3-Al(i-Bu)3-BrCH2CH2Br]. The polymerization behavior was studied in detail. The polymer was characterized by IR and elemental analysis. The poly(isoprene-b-1,2-epoxyhexane) glucose oxidase electrode, which was formed by immobilization of glucose oxidase on the poly (Ip-b-HEO) film using the electrochemical method, has kinetic characteristics of the typical enzyme-catalyzed reaction. The apparent Michaelis constant and activation energy for the immobilized glucose oxidase are 32.2 mmol/L and 37.2 kJ/mol, respectively.
The block copolymer of isoprene(Ip) and 1,2-epoxyhexane (HEO) was synthesized by rare earth coordination catalyst, [Nd(P204)3-Al(i-Bu)3-BrCH2CH2Br]. The polymerization behavior was studied in detail. The polymer was characterized by IR and elemental analysis. The poly(isoprene-b-1,2-epoxyhexane) glucose oxidase electrode, which was formed by immobilization of glucose oxidase on the poly (Ip-b-HEO) film using the electrochemical method, has kinetic characteristics of the typical enzyme-catalyzed reaction. The apparent Michaelis constant and activation energy for the immobilized glucose oxidase are 32.2 mmol/L and 37.2 kJ/mol, respectively.
2001, 18(5): 377-379
Abstract:
A modified Ubbelodhe viscometer with polytetrafluoroethylene capillary has been fabricated. The newly constructed viscometer was tested and compared with conventional glass viscometer by measuring the aqueous solution viscosity of a partially hydrolyzed polyacrylamide sample covering a considerable wide concentration range down to extremely dilute region. The interference from polymer adsorption onto the capillary inner wall surface on the viscosity measurements is completely avoided when the new modified viscosimeter is used instead of common glass viscometer. The experimental results indicate that the so called "polyelectrolyte effect" of solution viscosity is just only an apparent phenomenon due to polymer adsorption.
A modified Ubbelodhe viscometer with polytetrafluoroethylene capillary has been fabricated. The newly constructed viscometer was tested and compared with conventional glass viscometer by measuring the aqueous solution viscosity of a partially hydrolyzed polyacrylamide sample covering a considerable wide concentration range down to extremely dilute region. The interference from polymer adsorption onto the capillary inner wall surface on the viscosity measurements is completely avoided when the new modified viscosimeter is used instead of common glass viscometer. The experimental results indicate that the so called "polyelectrolyte effect" of solution viscosity is just only an apparent phenomenon due to polymer adsorption.
2001, 18(5): 380-383
Abstract:
A novel hybrid inorganic-organic mesoporous luminescent material (phen)2Eu/MCM-41 has been synthesized and characterized by XRD, IR, fluorescence and diffuse reflection spectra. In comparison with MCM-41, the hybrid mesoporous material has typical structure of MCM-41 and retains the same pore structure as MCM-41 after the assembly process. The hybrid mesoporous material shows characteristic emission spectra of Eu3+ under UV irradiation, but the excitation spectrum has shifted to blue region compared to that of pure rare earth complex. The decrease of site symmetry of Eu3+ has been found. The fluorescence lifetime of (phen)2Eu/MCM-41 is longer than that of pure rare earth complex. The spectra of hybrid mesoporous material have been discussed.
A novel hybrid inorganic-organic mesoporous luminescent material (phen)2Eu/MCM-41 has been synthesized and characterized by XRD, IR, fluorescence and diffuse reflection spectra. In comparison with MCM-41, the hybrid mesoporous material has typical structure of MCM-41 and retains the same pore structure as MCM-41 after the assembly process. The hybrid mesoporous material shows characteristic emission spectra of Eu3+ under UV irradiation, but the excitation spectrum has shifted to blue region compared to that of pure rare earth complex. The decrease of site symmetry of Eu3+ has been found. The fluorescence lifetime of (phen)2Eu/MCM-41 is longer than that of pure rare earth complex. The spectra of hybrid mesoporous material have been discussed.
2001, 18(5): 384-388
Abstract:
A series of biomolecular modified polyurethane were prepared. PEU-g-PEO-SO3Na, PEU-g-PEO-C18, PEU-g-PEO-SO2Lys, PEU-g-PEO-SO2Tyr, their surface properties were investigated by contact angle measurement. The polymer-water interface free energy VSW, the contribution of its polarity VSVp and its non-polarity VSVd were obtained by using captive bubble method. The results indicate that in the sulfonate modified PEU surface, the value of VSW increased with the content of PEO. When Lys or Tyr was grafted on the end of sulfonate PEU side chain, VSW decreased. The blood compatibility of the biomolecular modified polyurethanes was determined by measurements of platelet adhesion, plasma recalcification time (RTT) and prothrombin time (PTT). All biomolecular modified polyurethanes show good blood compatibility and potential in coating materials in blood contact device.
A series of biomolecular modified polyurethane were prepared. PEU-g-PEO-SO3Na, PEU-g-PEO-C18, PEU-g-PEO-SO2Lys, PEU-g-PEO-SO2Tyr, their surface properties were investigated by contact angle measurement. The polymer-water interface free energy VSW, the contribution of its polarity VSVp and its non-polarity VSVd were obtained by using captive bubble method. The results indicate that in the sulfonate modified PEU surface, the value of VSW increased with the content of PEO. When Lys or Tyr was grafted on the end of sulfonate PEU side chain, VSW decreased. The blood compatibility of the biomolecular modified polyurethanes was determined by measurements of platelet adhesion, plasma recalcification time (RTT) and prothrombin time (PTT). All biomolecular modified polyurethanes show good blood compatibility and potential in coating materials in blood contact device.
2001, 18(5): 389-391
Abstract:
The effects of heat treatment at different temperatures under Ar atmosphere on the specific surface area and particle size of nanometric lithium hydride as well as its catalytic activity in hydrogenation have been studied. The specific surface area of LiH treated at 300℃ decreases significantly, whereas a much higher catalytic activity is achieved with catalyst composed of nanometric LiH and Cp2TiCl2. This result indicates that the large specific surface area of nanometric LiH is a major factor but not the only factor for its high activity.
The effects of heat treatment at different temperatures under Ar atmosphere on the specific surface area and particle size of nanometric lithium hydride as well as its catalytic activity in hydrogenation have been studied. The specific surface area of LiH treated at 300℃ decreases significantly, whereas a much higher catalytic activity is achieved with catalyst composed of nanometric LiH and Cp2TiCl2. This result indicates that the large specific surface area of nanometric LiH is a major factor but not the only factor for its high activity.
2001, 18(5): 392-395
Abstract:
The polymerization of acrylonitrile catalyzed by [(ButCp)2NdMe]2/quarternary ammonium salt(sodium phenolate、sodium naptholate) was first studied. The catalytic activity of [(But-Cp)2NdMe]2(Cat) was greatly increased by adding quarternary ammonium salt, sodium phenolate or sodium naptholate, such as CH3(CH2)15NBrMe3, Me4NBr, (C4H9)4NBr, 2,6-di-Bu2t-4-MeC6H2ONa, 4-ButC6H4ONa and (2-MeC10H6ONa). The polymerization conditions were investigated, including the effects of the mole ratio of (C4H9)4NBr to (Cat), the amount of (Cat), monomer concentration, polymerization temperature and solvent. The conversion of acrylonitrile was as high as 65.4% at the polymerization conditions: [(C4H9)4NBr]/[Cat]=2, [Cat]=2.0×10-5 mol/g, x(M)=50%, 40℃, toluene, 2 h.
The polymerization of acrylonitrile catalyzed by [(ButCp)2NdMe]2/quarternary ammonium salt(sodium phenolate、sodium naptholate) was first studied. The catalytic activity of [(But-Cp)2NdMe]2(Cat) was greatly increased by adding quarternary ammonium salt, sodium phenolate or sodium naptholate, such as CH3(CH2)15NBrMe3, Me4NBr, (C4H9)4NBr, 2,6-di-Bu2t-4-MeC6H2ONa, 4-ButC6H4ONa and (2-MeC10H6ONa). The polymerization conditions were investigated, including the effects of the mole ratio of (C4H9)4NBr to (Cat), the amount of (Cat), monomer concentration, polymerization temperature and solvent. The conversion of acrylonitrile was as high as 65.4% at the polymerization conditions: [(C4H9)4NBr]/[Cat]=2, [Cat]=2.0×10-5 mol/g, x(M)=50%, 40℃, toluene, 2 h.
2001, 18(5): 396-399
Abstract:
The synthesis and characterization of metallocene complexes Cp2tMCl2[Cpt=tBuC5H4,M=Ti(Ⅰ), Zr(Ⅱ), Hf(Ⅲ)] are presented in catalyzation polymerization of butene-1. The metallocene catalysts and polybutenes have been characterized by IR, 1H NMR and EI-MS spectra and DSC measurements. The catalytic features for butene-1 polymerization were studied under different conditions. The results showed that Cp2tMCl2/MAO had high activity for butene-1 polymerization, improving the tacticity and molecular weight of the polymers obtained.
The synthesis and characterization of metallocene complexes Cp2tMCl2[Cpt=tBuC5H4,M=Ti(Ⅰ), Zr(Ⅱ), Hf(Ⅲ)] are presented in catalyzation polymerization of butene-1. The metallocene catalysts and polybutenes have been characterized by IR, 1H NMR and EI-MS spectra and DSC measurements. The catalytic features for butene-1 polymerization were studied under different conditions. The results showed that Cp2tMCl2/MAO had high activity for butene-1 polymerization, improving the tacticity and molecular weight of the polymers obtained.
2001, 18(5): 400-403
Abstract:
The reaction of an excess of 4,4'-oxydianiline (A) with alkyl halide has been found effective to synthesize N,N'-bis[2-(hydroxyethoxy)ethyl]-4,4'-oxydianiline(B). It is found that two new pseudotaxanes (A-CPQT、B-CPQT) are formed in solution by self-assembly of electron donor 4,4'-oxydianiline (A) and (B) with electron accepter cyclobis (paraquat-phenylene) tetracationic cyclophane (CPQT), respectively, which can be reversibly switched by acid-base action. The process is monitored by 1H NMR technique. The results showed that pseudorotaxane (B-CPQT) formation is probably encouraged by the hydrogen bonding sites:oxygen atoms along the polyether chains from dianiline rings form the [C-H-O] bonding with the hydrogen atoms in T position to the nitrogen atom in the bipyridinium rings on the cyclophane.
The reaction of an excess of 4,4'-oxydianiline (A) with alkyl halide has been found effective to synthesize N,N'-bis[2-(hydroxyethoxy)ethyl]-4,4'-oxydianiline(B). It is found that two new pseudotaxanes (A-CPQT、B-CPQT) are formed in solution by self-assembly of electron donor 4,4'-oxydianiline (A) and (B) with electron accepter cyclobis (paraquat-phenylene) tetracationic cyclophane (CPQT), respectively, which can be reversibly switched by acid-base action. The process is monitored by 1H NMR technique. The results showed that pseudorotaxane (B-CPQT) formation is probably encouraged by the hydrogen bonding sites:oxygen atoms along the polyether chains from dianiline rings form the [C-H-O] bonding with the hydrogen atoms in T position to the nitrogen atom in the bipyridinium rings on the cyclophane.
2001, 18(5): 404-407
Abstract:
1,2-Dihydro-2-(4-carboxylphenyl)-4-[4-(4-carboxylphenoxy)-3-methylphenyl]-phthalazin-1-one, a diacid monomer containing phthalazone moiety and arylene dianimes were used to synthesize polyamides. The monomer and polymers were studied by FT-IR, 1H NMR techniques. The polyamides obtained were soluble in polar aprotic solvents such as DMAc, NMP and had inherent viscosity of 1.25~1.58 dL/g (25℃, NMP). The Tg of the polyamides were above 280℃. The polyamide films had tensile strength 85~90 MPa, elongation at break 7%~11% tensile modulus 0.9~1.3 GPa, and the coefficient of electrical resistantce 1014~1016.
1,2-Dihydro-2-(4-carboxylphenyl)-4-[4-(4-carboxylphenoxy)-3-methylphenyl]-phthalazin-1-one, a diacid monomer containing phthalazone moiety and arylene dianimes were used to synthesize polyamides. The monomer and polymers were studied by FT-IR, 1H NMR techniques. The polyamides obtained were soluble in polar aprotic solvents such as DMAc, NMP and had inherent viscosity of 1.25~1.58 dL/g (25℃, NMP). The Tg of the polyamides were above 280℃. The polyamide films had tensile strength 85~90 MPa, elongation at break 7%~11% tensile modulus 0.9~1.3 GPa, and the coefficient of electrical resistantce 1014~1016.
2001, 18(5): 408-411
Abstract:
The leachate from a Hong Kong landfill, containing 15.70 g/L of chemical oxygen demand (COD) and 2.26 g/L of ammonia nitrogen (NH3-N), was first treated in a UASB (upflow anaerobic sludge blanket) reactor at 37℃. The process on average removed 90.4% of COD with 6.6 days of hydraulic retention at an organic loading rate of 2.37 g/(L·day) COD. The UASB effluent was further treated by the Fenton coagulation process using H2O2 and Fe2+. Under the optimal condition of 200 mg/L H2O2 and 300 mg/L Fe2+ and initial pH 6.0, 70% of residual COD in the UASB effluent was removed, of which 56% was removed by coagulation/precipitation and only 14% by free radical oxidation. It is obvious that H2O2 and Fe2+ had a strong synergistic effect on coagulation. The average COD in the final effluent was 447 mg/L. Removing each gram of COD required 0.18 g of H2O2 and 0.28 g of Fe2+, the Fenton coagulation process was discussed in this paper.
The leachate from a Hong Kong landfill, containing 15.70 g/L of chemical oxygen demand (COD) and 2.26 g/L of ammonia nitrogen (NH3-N), was first treated in a UASB (upflow anaerobic sludge blanket) reactor at 37℃. The process on average removed 90.4% of COD with 6.6 days of hydraulic retention at an organic loading rate of 2.37 g/(L·day) COD. The UASB effluent was further treated by the Fenton coagulation process using H2O2 and Fe2+. Under the optimal condition of 200 mg/L H2O2 and 300 mg/L Fe2+ and initial pH 6.0, 70% of residual COD in the UASB effluent was removed, of which 56% was removed by coagulation/precipitation and only 14% by free radical oxidation. It is obvious that H2O2 and Fe2+ had a strong synergistic effect on coagulation. The average COD in the final effluent was 447 mg/L. Removing each gram of COD required 0.18 g of H2O2 and 0.28 g of Fe2+, the Fenton coagulation process was discussed in this paper.
2001, 18(5): 412-415
Abstract:
Titanium and hafnium bimetallic catalyst prepared by chemical reaction method using MgCl2 as support shows a high activity and good polymer particle size distribution. Compared with catalyst containing only titanium, the titanium-hafnium bimetallic catalyst exhibits better performance and produces polyethylenes with higher molecular weight and wider molecular weight distribution and gives lower density copolymer of ethylene with butene-1. The MFR values of polyethylene obtained decrease with increase in partial hydrogen pressure. High molecular weight shoulders in GPC profile demonstrates that moderate or low molecular weight polyethylene is due to the titanium species while the hafnium active species produce high molecular weight polyethylene. This bimetallic catalyst is suggested to have a promising application in production of polyethylenes with broad molecular weight distributions.
Titanium and hafnium bimetallic catalyst prepared by chemical reaction method using MgCl2 as support shows a high activity and good polymer particle size distribution. Compared with catalyst containing only titanium, the titanium-hafnium bimetallic catalyst exhibits better performance and produces polyethylenes with higher molecular weight and wider molecular weight distribution and gives lower density copolymer of ethylene with butene-1. The MFR values of polyethylene obtained decrease with increase in partial hydrogen pressure. High molecular weight shoulders in GPC profile demonstrates that moderate or low molecular weight polyethylene is due to the titanium species while the hafnium active species produce high molecular weight polyethylene. This bimetallic catalyst is suggested to have a promising application in production of polyethylenes with broad molecular weight distributions.
2001, 18(5): 416-418
Abstract:
Some polyurethane elastomers with different macromolecular structure were synthesized and their dynamic mechanical properties were determined. It is found that the compatibility between the soft segment and hard segment phases of the polyurethane is mainly depended on the macromolecular chain structure. The existence of graft chains has a great effect on the morphology and damping property of the polyurethane elastomers.
Some polyurethane elastomers with different macromolecular structure were synthesized and their dynamic mechanical properties were determined. It is found that the compatibility between the soft segment and hard segment phases of the polyurethane is mainly depended on the macromolecular chain structure. The existence of graft chains has a great effect on the morphology and damping property of the polyurethane elastomers.
2001, 18(5): 419-421
Abstract:
In Liaohe oil residue nickel content is high and vanadium content is low. There are some kinds of metalloporphyrin in Liaohe oil residue. In this paper the nickel porphyrin is isolated by extraction with acetonitrile. The isolated nickel porphyrin has a characteristic peak at 552 nm, by which the concentration of nickel as porphyrins is determined. The nickel porphyrin is dematallated with methanesulfonic acid. The demetallated porphyrin has four peaks in visible band with Ⅳ> Ⅲ> Ⅱ> Ⅰ. This shows ETIO is the main porphyrin compound in Liaohe oil residue.
In Liaohe oil residue nickel content is high and vanadium content is low. There are some kinds of metalloporphyrin in Liaohe oil residue. In this paper the nickel porphyrin is isolated by extraction with acetonitrile. The isolated nickel porphyrin has a characteristic peak at 552 nm, by which the concentration of nickel as porphyrins is determined. The nickel porphyrin is dematallated with methanesulfonic acid. The demetallated porphyrin has four peaks in visible band with Ⅳ> Ⅲ> Ⅱ> Ⅰ. This shows ETIO is the main porphyrin compound in Liaohe oil residue.
