Login In
2004 Volume 22 Issue 1
2004, 22(1): 1-5
Abstract:
A novel AB3-type monomer was prepared from gallic acid and DL-2-aminobutyric acid, and used for the synthesis of the biocompatible hyperbranched poly(ester-amide)s by self-polycondensation. The polymers were characterized via FTIR and NMR spectroscopy and thermal analysis, and the average degree of branching of the polymers was estimated to be 0.75.The polymers with abundant acetyl end groups were found to be amorphous with lower intrinsic viscosity, better thermalstability and excellent solubility.
A novel AB3-type monomer was prepared from gallic acid and DL-2-aminobutyric acid, and used for the synthesis of the biocompatible hyperbranched poly(ester-amide)s by self-polycondensation. The polymers were characterized via FTIR and NMR spectroscopy and thermal analysis, and the average degree of branching of the polymers was estimated to be 0.75.The polymers with abundant acetyl end groups were found to be amorphous with lower intrinsic viscosity, better thermalstability and excellent solubility.
2004, 22(1): 7-16
Abstract:
Hindered phenol compound 3,9-bis{1,1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80) is a polymorphous material with different physical structures. The initial AO-80 is highly crystalline, whereas AO-80 obtained by cooling from its molten state is an amorphous material. Annealing treatment below the melting point of AO-80 results in structural development. The mixture of chlorinated polyethylene (CPE) and vitrified AO-80 particles exhibits a dramatic change in the dynamic mechanical properties during heat treatment at 130"C. This change can be attributed to the decomposition of the vitrified AO-80 particles and the hybridization of two constituents. The vitrified AO-80 particles can crystallize again in a CPE matrix by annealing at 100"C, but this crystal is different from that of the initial AO-80 in its microstructure. In addition, the incorporation of CPE chains caused a dramatic increase in the modulus. As a result, the AO-80 crystal particles that contain some CPE chains act as multifunctional cross-links and the CPE/AO-80 hybrid was found to be a new type of elastomer.
Hindered phenol compound 3,9-bis{1,1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80) is a polymorphous material with different physical structures. The initial AO-80 is highly crystalline, whereas AO-80 obtained by cooling from its molten state is an amorphous material. Annealing treatment below the melting point of AO-80 results in structural development. The mixture of chlorinated polyethylene (CPE) and vitrified AO-80 particles exhibits a dramatic change in the dynamic mechanical properties during heat treatment at 130"C. This change can be attributed to the decomposition of the vitrified AO-80 particles and the hybridization of two constituents. The vitrified AO-80 particles can crystallize again in a CPE matrix by annealing at 100"C, but this crystal is different from that of the initial AO-80 in its microstructure. In addition, the incorporation of CPE chains caused a dramatic increase in the modulus. As a result, the AO-80 crystal particles that contain some CPE chains act as multifunctional cross-links and the CPE/AO-80 hybrid was found to be a new type of elastomer.
2004, 22(1): 17-23
Abstract:
The rod-like assembly from BAB block copolymer with hydrophilic middle block A in aqueous solution was described. The copolymer used is polystyrene (PS)39-b-poly(4-vinylpyridine)(P4VP)98-b-PS39 (the subscripts are the average polymerization degree of corresponding blocks) triblock copolymer with Mw/Mn = 1.15. The aggregates were characterized by transmission electron microscopy and atomic force microscopy. The dependence of rod-like aggregate formation on solvents, pH, and polymer concentrations was investigated. The rod-like aggregates were formed when using dioxane as initial solvent, while spherical micelles were formed using DMF. Elevating pH values from 4 to 5 to 7 and decreasing initial copolymer concentrations from 1.5 wt% to 1.0 wt% to 0.5 wt% were favorable for the formation of well-defined rod-like aggregates. In addition, the bicontinuous rods and lamellae were observed when preparing colloid solutions in appropriate conditions.
The rod-like assembly from BAB block copolymer with hydrophilic middle block A in aqueous solution was described. The copolymer used is polystyrene (PS)39-b-poly(4-vinylpyridine)(P4VP)98-b-PS39 (the subscripts are the average polymerization degree of corresponding blocks) triblock copolymer with Mw/Mn = 1.15. The aggregates were characterized by transmission electron microscopy and atomic force microscopy. The dependence of rod-like aggregate formation on solvents, pH, and polymer concentrations was investigated. The rod-like aggregates were formed when using dioxane as initial solvent, while spherical micelles were formed using DMF. Elevating pH values from 4 to 5 to 7 and decreasing initial copolymer concentrations from 1.5 wt% to 1.0 wt% to 0.5 wt% were favorable for the formation of well-defined rod-like aggregates. In addition, the bicontinuous rods and lamellae were observed when preparing colloid solutions in appropriate conditions.
2004, 22(1): 25-30
Abstract:
The title compound, thiodiglycol dimethacrylate (TDGDMA), was synthesized from thiodiglycol and methacryloyl chloride by phase transfer catalysis reaction, and its structure was confirmed by FTIR and 1H-NMR analyses. TDGDMA possesses good polymerizability to produce a homopolymer resin with excellent transparency (T%, 90), moderate refractivity (nd20, 1.55), lower dispersivity (Abbe's number, 50.6) and higher glass transition temperature (Tg, 119℃). Through copolymerization with styrene (St) or styrene-4,4'-bismethacryloyloxydiphenylsulfone (BPSDMA), many properties of the copolymer such as refractive index, Abbe's number, strength, onset wavelength in the UV region and density were significantly modified. A copolymer resin with balanced properties between refractive index and dispersion was produced at the weight ratio of TDGDMA:St:BPSDMA (25:50:25), where nd20 and Abbe's number are 1.5815 and 36.5, respectively.
The title compound, thiodiglycol dimethacrylate (TDGDMA), was synthesized from thiodiglycol and methacryloyl chloride by phase transfer catalysis reaction, and its structure was confirmed by FTIR and 1H-NMR analyses. TDGDMA possesses good polymerizability to produce a homopolymer resin with excellent transparency (T%, 90), moderate refractivity (nd20, 1.55), lower dispersivity (Abbe's number, 50.6) and higher glass transition temperature (Tg, 119℃). Through copolymerization with styrene (St) or styrene-4,4'-bismethacryloyloxydiphenylsulfone (BPSDMA), many properties of the copolymer such as refractive index, Abbe's number, strength, onset wavelength in the UV region and density were significantly modified. A copolymer resin with balanced properties between refractive index and dispersion was produced at the weight ratio of TDGDMA:St:BPSDMA (25:50:25), where nd20 and Abbe's number are 1.5815 and 36.5, respectively.
2004, 22(1): 31-42
Abstract:
A new chelating polymer support has been prepared by suspension copolymerization of synthesized N,N'-bis(3-allyl salicylidene)ethylenediamine monomer Schiff base (N,N'-BSEDA) with styrene (St) and divinylbenzene (DVB) using azobisisobutyronitrile (AIBN) as initiator in the presence of poly(vinyl alcohol). The content and complexation ability of monomer Schiff base (N,N'-BSEDA) for cobalt(Ⅱ) ions in prepared crosslinked polymer beads have shown dependence on the amount of DVB used in reaction mixture. The amount of monomer Schiff base (N,N '-BSEDA) in crosslinked beads showed a substantial decreasing trend at high concentration of DVB in the reaction mixture (> 1.5 mol dm-3), hence the efficiency of complexation (EC%) and cobaltⅡion loading (EL%) of polymer beads showed a decreasing trend. The structure of monomer Schiff base (N,N'-BSEDA) and its cobalt(Ⅱ)complex on polymer support was elucidated by IR, UV and magnetic measurements. The catalytic activity of polymer bound cobalt(Ⅱ)Schiff base complex was evaluated by analyzing kinetic data of decomposition of hydrogen peroxide in the presence of either supported cobalt(Ⅱ)complex or free cobalt(Ⅱ)complex. The activation energy for the decomposition of hydrogen peroxide by polymer supported cobalt complex was found to be low (33.37 kJ mol-1) in comparison with unsupported cobalt(Ⅱ)complex (56.35 kJ mol-1). On the basis of experimental observations, reaction steps are proposed and a suitable rate expression derived.
A new chelating polymer support has been prepared by suspension copolymerization of synthesized N,N'-bis(3-allyl salicylidene)ethylenediamine monomer Schiff base (N,N'-BSEDA) with styrene (St) and divinylbenzene (DVB) using azobisisobutyronitrile (AIBN) as initiator in the presence of poly(vinyl alcohol). The content and complexation ability of monomer Schiff base (N,N'-BSEDA) for cobalt(Ⅱ) ions in prepared crosslinked polymer beads have shown dependence on the amount of DVB used in reaction mixture. The amount of monomer Schiff base (N,N '-BSEDA) in crosslinked beads showed a substantial decreasing trend at high concentration of DVB in the reaction mixture (> 1.5 mol dm-3), hence the efficiency of complexation (EC%) and cobaltⅡion loading (EL%) of polymer beads showed a decreasing trend. The structure of monomer Schiff base (N,N'-BSEDA) and its cobalt(Ⅱ)complex on polymer support was elucidated by IR, UV and magnetic measurements. The catalytic activity of polymer bound cobalt(Ⅱ)Schiff base complex was evaluated by analyzing kinetic data of decomposition of hydrogen peroxide in the presence of either supported cobalt(Ⅱ)complex or free cobalt(Ⅱ)complex. The activation energy for the decomposition of hydrogen peroxide by polymer supported cobalt complex was found to be low (33.37 kJ mol-1) in comparison with unsupported cobalt(Ⅱ)complex (56.35 kJ mol-1). On the basis of experimental observations, reaction steps are proposed and a suitable rate expression derived.
2004, 22(1): 43-47
Abstract:
Polyamide 11 (PA 11) is a widely used polyamide resin, but its application is limited since the impact properties,tensile strength, and thermal properties are not very satisfactory for industrial application. In order to improve the mechanical properties of PA 11, in this paper, the preparation of polyamide 11/clay nanocomposites (PACN) via in-situ intercalated polymerization was reported. SEM, TEM and XRD were employed to investigate the dispersion of clay sheet in the matrix. The results indicate that clay layers were homogeneously dispersed in PA11 matrix on a nano-scale, and an exfoliated and intercalated structure co-existed in the composites. The mechanical and thermal properties of the obtained nanocomposites were improved to certain extent by the addition of clay.
Polyamide 11 (PA 11) is a widely used polyamide resin, but its application is limited since the impact properties,tensile strength, and thermal properties are not very satisfactory for industrial application. In order to improve the mechanical properties of PA 11, in this paper, the preparation of polyamide 11/clay nanocomposites (PACN) via in-situ intercalated polymerization was reported. SEM, TEM and XRD were employed to investigate the dispersion of clay sheet in the matrix. The results indicate that clay layers were homogeneously dispersed in PA11 matrix on a nano-scale, and an exfoliated and intercalated structure co-existed in the composites. The mechanical and thermal properties of the obtained nanocomposites were improved to certain extent by the addition of clay.
2004, 22(1): 49-53
Abstract:
The column wicking technique was applied to estimate the surface free energy of cellulose, the importance of which is to obtain a real effective capillary radius, Reff, initially from the plot of Washburn penetration distance versus time.Since the cellulose sample could not be packed with good reproducibility, therefore, Reff can not be obtained readily from the slope of the plot. A method was developed in this paper by uniting all apparent packing heights with a unique value to deduce a real effective capillary radius. Based on the defined critical packing height related to the critical packing density, the surface free energy and acid-base properties of cellulose Sigma C8002 were estimated.
The column wicking technique was applied to estimate the surface free energy of cellulose, the importance of which is to obtain a real effective capillary radius, Reff, initially from the plot of Washburn penetration distance versus time.Since the cellulose sample could not be packed with good reproducibility, therefore, Reff can not be obtained readily from the slope of the plot. A method was developed in this paper by uniting all apparent packing heights with a unique value to deduce a real effective capillary radius. Based on the defined critical packing height related to the critical packing density, the surface free energy and acid-base properties of cellulose Sigma C8002 were estimated.
2004, 22(1): 55-61
Abstract:
The controlled free radical polymerization of styrene and isoprene initiated with benzoyl peroxide (BPO) in the presence of 2,2,6,6-tetramethyl piperidine-N-oxyl (TEMPO) at 125 ℃ were performed. The obtained polyisoprene and polystyrene homopolymers served as macroinitiators for block copolymerization of isoprene and styrene to synthesize poly-(styrene-b-isoprene) and poly(isoprene-b-styrene) diblock copolymers. Diblock copolymers with well-defined structures as well as controlled and narrow molecular weight distribution were obtained from the lower-mass polystyrene and polyisoprene homopolymers. These copolymers were found to be active as macroinitiators in the synthesis of the poly(styrene-b-isoprene-b-styrene) and poly(isoprene-b-styrene-b-isoprene) triblock copolymers. H-NMR spectroscopy and gel permeation chromatography (GPC) were used for the investigation of polymer structure, molecular weight and polydispersity (PD).
The controlled free radical polymerization of styrene and isoprene initiated with benzoyl peroxide (BPO) in the presence of 2,2,6,6-tetramethyl piperidine-N-oxyl (TEMPO) at 125 ℃ were performed. The obtained polyisoprene and polystyrene homopolymers served as macroinitiators for block copolymerization of isoprene and styrene to synthesize poly-(styrene-b-isoprene) and poly(isoprene-b-styrene) diblock copolymers. Diblock copolymers with well-defined structures as well as controlled and narrow molecular weight distribution were obtained from the lower-mass polystyrene and polyisoprene homopolymers. These copolymers were found to be active as macroinitiators in the synthesis of the poly(styrene-b-isoprene-b-styrene) and poly(isoprene-b-styrene-b-isoprene) triblock copolymers. H-NMR spectroscopy and gel permeation chromatography (GPC) were used for the investigation of polymer structure, molecular weight and polydispersity (PD).
2004, 22(1): 63-68
Abstract:
Some chiral binaphthyl crown ethers were synthesized. The anionic polymerization of methyl methacrylate (MMA) was carried out in the presence of t-BuOK, Ph2CHK or Ph2CHNa (RM), and RM coordination initiator by using chiral binaphthyl crown ethers as ligands, respectively. The results showed that in the former case the PMMA obtained has mainly isotactic structure but without optical activity, while in the later case the PMMA produced predominately has syndiotactic structure also without optical activity.
Some chiral binaphthyl crown ethers were synthesized. The anionic polymerization of methyl methacrylate (MMA) was carried out in the presence of t-BuOK, Ph2CHK or Ph2CHNa (RM), and RM coordination initiator by using chiral binaphthyl crown ethers as ligands, respectively. The results showed that in the former case the PMMA obtained has mainly isotactic structure but without optical activity, while in the later case the PMMA produced predominately has syndiotactic structure also without optical activity.
2004, 22(1): 69-75
Abstract:
The negative ion implantation technique was applied to modify polymer surfaces of culture dishes for neuronal cells, PC12h. The silver negative ion (Ag-)-implantation was carried out at an ion energy of 20 keV and a dose of 3 ×1015 ions/cm2 with non-treated polystyrene (NTPS), tissue culture polystyrene (TCPS), and collagen-coated TCPS-Iwaki (CCPS). Ag--implanted surfaces of Ag/NTPS, Ag/TCPS, and Ag/CCPS were studied with respect to contact angle and/or chemical composition. The numerical values of contact angles on Ag/NTPS and Ag/TCPS were similar within experimental error, indicating the resemblance in their hydrophobicity and hydrophilicity. The PC12h cells, however, were attached only to the Ag--implanted region of NTPS, but not to the non-implanted NTPS region. Moreover, the neurite outgrowth was also observed to extend specifically along the Ag--implanted region of NTPS but not on the non-implanted NTPS region, although neurites extended towards all directions on collagen-coated TCPS as a control surface. There was no remarkable difference in neurite outgrowth among Ag--implanted regions of TCPS and CCPS. Thus Ag/NTPS region was affirmed to promote highly selective attachment, growth, and differentiation of PC12h cells, although its mechanism is still unknown.
The negative ion implantation technique was applied to modify polymer surfaces of culture dishes for neuronal cells, PC12h. The silver negative ion (Ag-)-implantation was carried out at an ion energy of 20 keV and a dose of 3 ×1015 ions/cm2 with non-treated polystyrene (NTPS), tissue culture polystyrene (TCPS), and collagen-coated TCPS-Iwaki (CCPS). Ag--implanted surfaces of Ag/NTPS, Ag/TCPS, and Ag/CCPS were studied with respect to contact angle and/or chemical composition. The numerical values of contact angles on Ag/NTPS and Ag/TCPS were similar within experimental error, indicating the resemblance in their hydrophobicity and hydrophilicity. The PC12h cells, however, were attached only to the Ag--implanted region of NTPS, but not to the non-implanted NTPS region. Moreover, the neurite outgrowth was also observed to extend specifically along the Ag--implanted region of NTPS but not on the non-implanted NTPS region, although neurites extended towards all directions on collagen-coated TCPS as a control surface. There was no remarkable difference in neurite outgrowth among Ag--implanted regions of TCPS and CCPS. Thus Ag/NTPS region was affirmed to promote highly selective attachment, growth, and differentiation of PC12h cells, although its mechanism is still unknown.
2004, 22(1): 77-82
Abstract:
A novel coordinated complex [(5-nitrophen)Pd(CF3CO2)2] (5-nitrophen = 5-nitro-1,10-phenanthroline) was first synthesized. By using XPS, IR, and 1H-NMR, its coordination unit was studied in comparison with those of complexes N-N)Pd(CH3CO2)2] and [(N-N)Pd(CF3CO2)2]. The H2,9 proton signals of 1H-NMR spectra of the complexes are excellent probes to monitor the evolution of the environment of the palladium atom. The state of anionic coordination was confirmed by the presence of IR absorption peaks of COO in complexes ([(N — N)Pd(CH3CO2)2] and [(N —N)Pd(CF3CO2)2]). Bonding energies of N1s and Pd3d5 obtained from XPS data testified to the strength of the N-Pd coordinating bond. The conclusion can be drawn by nalyzing these data from IR, XPS and H-NMR that it is the unsymmetrical substitution of the 1,10-phenanthroline (phen) that makes the [(5-nitrophen)Pd(CF3CO2)2] more active.Experimental results showed that [(5-nitrophen)Pd(CF3CO2)2] exhibits much higher activity than [(bipy)Pd(CF3CO2)2] (1,1'-bipyridine = bipy) and [(phen)Pd(CF3CO2)2] under the same conditions.
A novel coordinated complex [(5-nitrophen)Pd(CF3CO2)2] (5-nitrophen = 5-nitro-1,10-phenanthroline) was first synthesized. By using XPS, IR, and 1H-NMR, its coordination unit was studied in comparison with those of complexes N-N)Pd(CH3CO2)2] and [(N-N)Pd(CF3CO2)2]. The H2,9 proton signals of 1H-NMR spectra of the complexes are excellent probes to monitor the evolution of the environment of the palladium atom. The state of anionic coordination was confirmed by the presence of IR absorption peaks of COO in complexes ([(N — N)Pd(CH3CO2)2] and [(N —N)Pd(CF3CO2)2]). Bonding energies of N1s and Pd3d5 obtained from XPS data testified to the strength of the N-Pd coordinating bond. The conclusion can be drawn by nalyzing these data from IR, XPS and H-NMR that it is the unsymmetrical substitution of the 1,10-phenanthroline (phen) that makes the [(5-nitrophen)Pd(CF3CO2)2] more active.Experimental results showed that [(5-nitrophen)Pd(CF3CO2)2] exhibits much higher activity than [(bipy)Pd(CF3CO2)2] (1,1'-bipyridine = bipy) and [(phen)Pd(CF3CO2)2] under the same conditions.
2004, 22(1): 83-89
Abstract:
A series of cyclic (arylene phosphonate) oligomers were prepared by reaction of phenylphosphonic dichloride(PPD) with various bisphenols under pseudo-high dilution conditions via interfacial polycondensation. The yield of cyclic(arylene phosphonate) oligomers is over 85% by using hexadecyltrimethylammoniun bromide as phase transfer catalyst(PTC) at 0 ℃ . The structures of the cyclic oligomers were confirmed by a combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and IR analysis. These cyclic oligomers undergo facile ring-opening polymerization in the melt by using potassium 4,4'-biphenoxide as the initiator to give linear polyphosphonate. Free-radical ring-opening polymerization of cyclic(arylene phosphonate) oligomers containing sulfur linkages was also performed in the melt using 2,2'-dithiobis(benzothiazole) (DTB) as the initiator at 270 ℃ and the resulting polymer had a Mw, of 8 × 103 with a molecular weight distribution of 4. Ring-opening copolymerization of these cyclic oligomers with cyclic carbonate oligomers was also achieved. The average molecular weight of the resulting copolymer is higher than the corresponding homopolymer and the thermal stability of the copolymer is better than the corresponding homopolymer.
A series of cyclic (arylene phosphonate) oligomers were prepared by reaction of phenylphosphonic dichloride(PPD) with various bisphenols under pseudo-high dilution conditions via interfacial polycondensation. The yield of cyclic(arylene phosphonate) oligomers is over 85% by using hexadecyltrimethylammoniun bromide as phase transfer catalyst(PTC) at 0 ℃ . The structures of the cyclic oligomers were confirmed by a combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and IR analysis. These cyclic oligomers undergo facile ring-opening polymerization in the melt by using potassium 4,4'-biphenoxide as the initiator to give linear polyphosphonate. Free-radical ring-opening polymerization of cyclic(arylene phosphonate) oligomers containing sulfur linkages was also performed in the melt using 2,2'-dithiobis(benzothiazole) (DTB) as the initiator at 270 ℃ and the resulting polymer had a Mw, of 8 × 103 with a molecular weight distribution of 4. Ring-opening copolymerization of these cyclic oligomers with cyclic carbonate oligomers was also achieved. The average molecular weight of the resulting copolymer is higher than the corresponding homopolymer and the thermal stability of the copolymer is better than the corresponding homopolymer.
2004, 22(1): 91-98
Abstract:
An amphiphilic graft polymer, (PAM-g-PBA), polyacrylamide (PAM) having poly(n-butyl acrylate) (PBA) side chains, was obtained by radical copolymerization of acrylamide with PBA macromer in solution. The macromer was synthesized by free radical polymerization of butyl acrylate in the presence of different amounts of thioglycolic acid as the chain transfer agent, followed by termination with glycidyl methacrylate. The reactivity ratio and effects of copolymerization conditions on the conversion of macromer or grafting efficiency were studied. The crude products were purified by extraction with toluene and water successively. The purified graft copolymer was characterized by IR, DSC and TEM. PAM-g-PBA can bring about microphase separation and exhibits good emulsifying properties and water absorbency. PAM-g-PBA exhibits a very good compatibilizing effect on the acrylic rubber/poly(vinyl chloride) blends. 2%-3% of the graft copolymer is enough for enhancing the tensile strength of the blends. The tensile strength of the blends is more than twice that without the compatibilizer. DSC and SEM demonstrated the enhancement of compatibility in the presence of the graft copolymer.
An amphiphilic graft polymer, (PAM-g-PBA), polyacrylamide (PAM) having poly(n-butyl acrylate) (PBA) side chains, was obtained by radical copolymerization of acrylamide with PBA macromer in solution. The macromer was synthesized by free radical polymerization of butyl acrylate in the presence of different amounts of thioglycolic acid as the chain transfer agent, followed by termination with glycidyl methacrylate. The reactivity ratio and effects of copolymerization conditions on the conversion of macromer or grafting efficiency were studied. The crude products were purified by extraction with toluene and water successively. The purified graft copolymer was characterized by IR, DSC and TEM. PAM-g-PBA can bring about microphase separation and exhibits good emulsifying properties and water absorbency. PAM-g-PBA exhibits a very good compatibilizing effect on the acrylic rubber/poly(vinyl chloride) blends. 2%-3% of the graft copolymer is enough for enhancing the tensile strength of the blends. The tensile strength of the blends is more than twice that without the compatibilizer. DSC and SEM demonstrated the enhancement of compatibility in the presence of the graft copolymer.
