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2003 Volume 21 Issue 4
2003, 21(4): 399-403
Abstract:
Polypyrrole microstructrues with morphology like bowls, cups, goblets and bottles have been electrochemicallygenerated by direct oxidation of pyrrole on p-silicon substrate in the aqueous solution of camphorsulfonic acid. The well-ordered microstructures can stand upright on the working electrode surface and their morphological features can be easilycontrolled by changing the electrochemical polymerization conditions. The growing process of microstructures was studiedby scanning electron microscopy. The microstructures made of polypyrrile films in doped state were characterized by Raman and Infrared spectra.
Polypyrrole microstructrues with morphology like bowls, cups, goblets and bottles have been electrochemicallygenerated by direct oxidation of pyrrole on p-silicon substrate in the aqueous solution of camphorsulfonic acid. The well-ordered microstructures can stand upright on the working electrode surface and their morphological features can be easilycontrolled by changing the electrochemical polymerization conditions. The growing process of microstructures was studiedby scanning electron microscopy. The microstructures made of polypyrrile films in doped state were characterized by Raman and Infrared spectra.
2003, 21(4): 405-412
Abstract:
Surface morphology and composition of solution-cast films of poly(methyl methacrylate)-g-poly(ethylene oxide)(PMMA-g-PEO) were investigated by using XPS, DSC, SEM and contact angle measurement. The microphase separatedstructure of the copolymers was studied by TEM. Generally, for the same graft copolymer, the surface content of PEO orhydrophilicity can be as follows: Surface treated with petroleum ether or cyclohexane>surface untreated with solvent>surface treated with water or ethyl alcohol. Graft copolymer having longer PEO side chains and higher PEO content shows a separated PEO phase with even a certain degree of crystallinity on the surface.PEO crystallinity was destroyed by water or ethyl alcohol treatment;however,surface treatment with petroleum ether or cyclohexane favors the growth of PEO crystal.TEM shows that graft copolymers with longer PEO side chains (Mn of PEO,3200)may readily undergo microphase separation and the shape and size of domains depend on the copolymer's composition.
Surface morphology and composition of solution-cast films of poly(methyl methacrylate)-g-poly(ethylene oxide)(PMMA-g-PEO) were investigated by using XPS, DSC, SEM and contact angle measurement. The microphase separatedstructure of the copolymers was studied by TEM. Generally, for the same graft copolymer, the surface content of PEO orhydrophilicity can be as follows: Surface treated with petroleum ether or cyclohexane>surface untreated with solvent>surface treated with water or ethyl alcohol. Graft copolymer having longer PEO side chains and higher PEO content shows a separated PEO phase with even a certain degree of crystallinity on the surface.PEO crystallinity was destroyed by water or ethyl alcohol treatment;however,surface treatment with petroleum ether or cyclohexane favors the growth of PEO crystal.TEM shows that graft copolymers with longer PEO side chains (Mn of PEO,3200)may readily undergo microphase separation and the shape and size of domains depend on the copolymer's composition.
2003, 21(4): 413-418
Abstract:
Polypropylene/montmorillonite (PP/MMT)nanocomposites were prepared by in-situ polymerization using aMMT/MgCl2/TiCl4-EB Ziegler-Natta catalyst activated by triethylaluminum(TEA). The enlarged layer spacing of MMT wasconfirmed by X-ray wide angle diffraction (WAXD), demonstrating that MMT were intercalated by the catalyst components.X-ray photoelectron spectrometry (XPS) analysis proved that TiCl4 was mainly supported on MgCl2 instead of on the surfaceof MMT The exfoliated structure of MMT layers in the PP matrix of PP/MMT composites was demonstrated by WAXD patterns and transmission electron microscopy (TEM) observation.The higher glass transition temperature and higher storage modulus of the PP/MMT composites in comparison with pure PP were revealed by dynamic mechanical analysis(DMA).
Polypropylene/montmorillonite (PP/MMT)nanocomposites were prepared by in-situ polymerization using aMMT/MgCl2/TiCl4-EB Ziegler-Natta catalyst activated by triethylaluminum(TEA). The enlarged layer spacing of MMT wasconfirmed by X-ray wide angle diffraction (WAXD), demonstrating that MMT were intercalated by the catalyst components.X-ray photoelectron spectrometry (XPS) analysis proved that TiCl4 was mainly supported on MgCl2 instead of on the surfaceof MMT The exfoliated structure of MMT layers in the PP matrix of PP/MMT composites was demonstrated by WAXD patterns and transmission electron microscopy (TEM) observation.The higher glass transition temperature and higher storage modulus of the PP/MMT composites in comparison with pure PP were revealed by dynamic mechanical analysis(DMA).
2003, 21(4): 419-425
Abstract:
On the molecular level, it is believed that polymers containing zwitterionic structures should be compatible withblood. In this work polyurethane films were grafted with sulfobetaine by a three-step procedure. In the first step, the films'surfaces were treated with hexamethylene diisocyanate (HDI) in toluene at 50℃ in the presence of di-n-butyl tin dilaurate(DBTDL) as a catalyst. The extent of the reaction was monitored by ATR-IR spectra; a maximum number of free NCO groups was obtained after a reaction time of 90 min.In the second step,the hydroxyl groups of N,N-dimethylethanolamine(DMEA) were allowed to react in toluene with NCO groups bound on the surface.In the third step,sulfobetaines were formed on the surface through the ring-opening reaction between tertiary amine of DMEA and 1,3-propanesultone(PS).The surfaces of the films were characterized by ATR-IR and XPS showing that the grafted surfaces were composed of sulfobetaine.The results of the contact angle measurement show that the surface was strongly hydrophilic.The platelet adhesion test demonstrated that the films grafted with sulfobetaine have excellent blood compatibility.
On the molecular level, it is believed that polymers containing zwitterionic structures should be compatible withblood. In this work polyurethane films were grafted with sulfobetaine by a three-step procedure. In the first step, the films'surfaces were treated with hexamethylene diisocyanate (HDI) in toluene at 50℃ in the presence of di-n-butyl tin dilaurate(DBTDL) as a catalyst. The extent of the reaction was monitored by ATR-IR spectra; a maximum number of free NCO groups was obtained after a reaction time of 90 min.In the second step,the hydroxyl groups of N,N-dimethylethanolamine(DMEA) were allowed to react in toluene with NCO groups bound on the surface.In the third step,sulfobetaines were formed on the surface through the ring-opening reaction between tertiary amine of DMEA and 1,3-propanesultone(PS).The surfaces of the films were characterized by ATR-IR and XPS showing that the grafted surfaces were composed of sulfobetaine.The results of the contact angle measurement show that the surface was strongly hydrophilic.The platelet adhesion test demonstrated that the films grafted with sulfobetaine have excellent blood compatibility.
2003, 21(4): 427-431
Abstract:
The radical copolymerization of methyl methacrylate and 2-hydroxyethyl methacrylate was carried out via atomtransfer radical polymerization (ATRP) initiated by ethyl 2-bromoisobutyrate and catalyzed by CuBr/2,2'-bipyridinecomplex. This polymerization proceeds in a living fashion with controlled molecular weight and low polydispersity. Theobtained copolymer was esterified with 2-bromoisobutylryl bromide yielding a macroinitiator, poly(methyl methacrylate-co-2-hydroxyethyl methacrylate-co-2-(2-bromoisobutyryloxy)ethyl methacrylate),and its structure was characterized by 1H-NMR.This macroinitiator was used for ATRP of styrene to synthesize poly(methyl methacrylate)-graft-polystyrene.The molecular weight of graft copolymer increased with the monomer conversion,and the polydispersity remained relatively low.The individual grafted polystyrene chains were eleaved from the macroinitiator backbone by hydrolysis and the hydrolyzed product was characterized by 1H-NMR and GPC.
The radical copolymerization of methyl methacrylate and 2-hydroxyethyl methacrylate was carried out via atomtransfer radical polymerization (ATRP) initiated by ethyl 2-bromoisobutyrate and catalyzed by CuBr/2,2'-bipyridinecomplex. This polymerization proceeds in a living fashion with controlled molecular weight and low polydispersity. Theobtained copolymer was esterified with 2-bromoisobutylryl bromide yielding a macroinitiator, poly(methyl methacrylate-co-2-hydroxyethyl methacrylate-co-2-(2-bromoisobutyryloxy)ethyl methacrylate),and its structure was characterized by 1H-NMR.This macroinitiator was used for ATRP of styrene to synthesize poly(methyl methacrylate)-graft-polystyrene.The molecular weight of graft copolymer increased with the monomer conversion,and the polydispersity remained relatively low.The individual grafted polystyrene chains were eleaved from the macroinitiator backbone by hydrolysis and the hydrolyzed product was characterized by 1H-NMR and GPC.
2003, 21(4): 433-436
Abstract:
Sulfur-containing monomers have received special interest from researchers because of their outstanding opticalperformance. Using the reaction between 2-phenylthioethyl-1-mercaptan and p-chloromethylstyrene, a new vinyl monomer4-(2-phenylthioethylthiomethyl)styrene (PTETMSt) was synthesized. Its structure was characterized by FT-IR and NMR.Copolymerization of styrene and PTETMSt was investigated. The data show that poly(styrene-co-PTETMSt) has higher refractive index, lower density and percentage of water absorption.The copolymer can be used on optical materials.
Sulfur-containing monomers have received special interest from researchers because of their outstanding opticalperformance. Using the reaction between 2-phenylthioethyl-1-mercaptan and p-chloromethylstyrene, a new vinyl monomer4-(2-phenylthioethylthiomethyl)styrene (PTETMSt) was synthesized. Its structure was characterized by FT-IR and NMR.Copolymerization of styrene and PTETMSt was investigated. The data show that poly(styrene-co-PTETMSt) has higher refractive index, lower density and percentage of water absorption.The copolymer can be used on optical materials.
2003, 21(4): 437-442
Abstract:
The formation of polymer and hydrogel from aqueous solutions having 20, 30 and 40% concentrations ofacrylamide monomer by γ-ray irradiation processing in the dose range 0.06-30 kGy using a Co-60 source and theircharacterization have been observed. Polymer conversion and gel fraction are found to depend on radiation doses. Polymerconversion increases with the increase of dose, depending on the solution concentration, where maximum conversion isachieved at 0.18, 0.16 and 0.10 kGy for 20%, 30% and 40% concentrations,respectively.On the other hand,gel fraction increases with dose from the gel point(0.12 kGy) for all concentrations,where 100% conversion of gel occurs at doses ≥ 5 kGy.Tensile strength,wiscosity and molecular weight(Mw) of polymer samples increase with both the dose and the concentration,showing a high value of Mw up to ≈102.Swelling of hydrogels under water with respect to time varies due to the variation of cross-linking density formed in the gels and the maximum swelling mainly within 24 h.A remarkable change of surface morphology reveals characteristic features of monomer,polymer and hydrogel films.
The formation of polymer and hydrogel from aqueous solutions having 20, 30 and 40% concentrations ofacrylamide monomer by γ-ray irradiation processing in the dose range 0.06-30 kGy using a Co-60 source and theircharacterization have been observed. Polymer conversion and gel fraction are found to depend on radiation doses. Polymerconversion increases with the increase of dose, depending on the solution concentration, where maximum conversion isachieved at 0.18, 0.16 and 0.10 kGy for 20%, 30% and 40% concentrations,respectively.On the other hand,gel fraction increases with dose from the gel point(0.12 kGy) for all concentrations,where 100% conversion of gel occurs at doses ≥ 5 kGy.Tensile strength,wiscosity and molecular weight(Mw) of polymer samples increase with both the dose and the concentration,showing a high value of Mw up to ≈102.Swelling of hydrogels under water with respect to time varies due to the variation of cross-linking density formed in the gels and the maximum swelling mainly within 24 h.A remarkable change of surface morphology reveals characteristic features of monomer,polymer and hydrogel films.
2003, 21(4): 443-446
Abstract:
The effects of styrene-ethylene/propylene (SEP) diblock copolymer on the morphology and mechanical propertiesof polypropylene/polystyrene (PP/PS) blends were investigated. The results showed that SEP diblock copolymer, acting as acompatibilizer in PP/PS immiscible blends, can diminish the coalescence of the dispersed particles, reduce their averageparticle size, change their phase morphologies significantly, and increase the mechanical properties. It was found that SEP has better compatibilization effects on the PP/PS(20/80)blends.
The effects of styrene-ethylene/propylene (SEP) diblock copolymer on the morphology and mechanical propertiesof polypropylene/polystyrene (PP/PS) blends were investigated. The results showed that SEP diblock copolymer, acting as acompatibilizer in PP/PS immiscible blends, can diminish the coalescence of the dispersed particles, reduce their averageparticle size, change their phase morphologies significantly, and increase the mechanical properties. It was found that SEP has better compatibilization effects on the PP/PS(20/80)blends.
2003, 21(4): 447-452
Abstract:
Suspended emulsion polymerization was used to prepare poly(vinyl chloride) (PVC) resin. Fine PVC particleswere formed at low polymerization conversions. The amount of fine panicles decreases as conversion increases anddisappears at conversions greater than 30%. Scanning electron micrographs show that PVC grains are composed of looselycoalesced primary particles, especially for PVC resins prepared in the presence of poly(vinyl alcohol) dispersant. The size ofprimary particles increases and porosity decreases with the increase of conversion.In view of the particle features of PVC resin,a particle formation mechanism including the formation of primary particles and grains is proposed.The formation process of primary particles includes the formation of particle nuclei,coalescence of particle nuclei to form primary particles,and growth of primary particles.PVC grains are formed by the coagulation of primary particles.The loose coalescence of primary particles is caused by the colloidal stability of primary particles and the low swelling degree of vinyl chloride in the primary particles.
Suspended emulsion polymerization was used to prepare poly(vinyl chloride) (PVC) resin. Fine PVC particleswere formed at low polymerization conversions. The amount of fine panicles decreases as conversion increases anddisappears at conversions greater than 30%. Scanning electron micrographs show that PVC grains are composed of looselycoalesced primary particles, especially for PVC resins prepared in the presence of poly(vinyl alcohol) dispersant. The size ofprimary particles increases and porosity decreases with the increase of conversion.In view of the particle features of PVC resin,a particle formation mechanism including the formation of primary particles and grains is proposed.The formation process of primary particles includes the formation of particle nuclei,coalescence of particle nuclei to form primary particles,and growth of primary particles.PVC grains are formed by the coagulation of primary particles.The loose coalescence of primary particles is caused by the colloidal stability of primary particles and the low swelling degree of vinyl chloride in the primary particles.
2003, 21(4): 453-457
Abstract:
8-Aminoquinoline nickel dichloride and bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2) were supportedsimultaneously on silica to produce branched polyethylene successfully by combined polymerization. The supportedpolymerization results showed that the molecular weight of polyethylene increased while the molecular weight distributionbecame wider and the molecular chains of oligomers remaning in the final solution became shorter as compared to theoligomers obtained in polymerization processes with pure 8-aminoquinoline nickel dichloride catalysis,as well as the Cp2ZrCl2 and nickel combination system.With decreasing amount of Ni catalyst in the supported catalyst,the molecular chains of oligomers in the resulting solution became shorter,while α-olefin selectivity increased.
8-Aminoquinoline nickel dichloride and bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2) were supportedsimultaneously on silica to produce branched polyethylene successfully by combined polymerization. The supportedpolymerization results showed that the molecular weight of polyethylene increased while the molecular weight distributionbecame wider and the molecular chains of oligomers remaning in the final solution became shorter as compared to theoligomers obtained in polymerization processes with pure 8-aminoquinoline nickel dichloride catalysis,as well as the Cp2ZrCl2 and nickel combination system.With decreasing amount of Ni catalyst in the supported catalyst,the molecular chains of oligomers in the resulting solution became shorter,while α-olefin selectivity increased.
2003, 21(4): 459-464
Abstract:
The effect of radiation on high-charge-density cationic polymer, polydiallyl-dimethyl ammonium chloride (poly-DADMAC), in dilute aqueous solution was investigated. The irradiated samples were characterized in terms of reducedviscosity and electric conductivity. The crosslinking reaction of polyDADMAC chains occurs preferentially in the irradiatedsamples at a concentration of polyDADMAC higher than 1.3 g/100 mL that was induced indirectly by the OH radicals, oneof the radiolysis products of water. In more dilute samples(less than 0.8g/100 mL) the chain scission of macro radicals appears to be the main reaction.N2O atmosphere enhances the crosslinking due to the extra OH radicals produced by reaction between N2O and eaq-,another radiolysis products of water.Methanol and some mineral salts such as KCl,KBr inhibit the crosslinking to a certain extent.The mechanism of sensitization and inhibition is discussed in detail.
The effect of radiation on high-charge-density cationic polymer, polydiallyl-dimethyl ammonium chloride (poly-DADMAC), in dilute aqueous solution was investigated. The irradiated samples were characterized in terms of reducedviscosity and electric conductivity. The crosslinking reaction of polyDADMAC chains occurs preferentially in the irradiatedsamples at a concentration of polyDADMAC higher than 1.3 g/100 mL that was induced indirectly by the OH radicals, oneof the radiolysis products of water. In more dilute samples(less than 0.8g/100 mL) the chain scission of macro radicals appears to be the main reaction.N2O atmosphere enhances the crosslinking due to the extra OH radicals produced by reaction between N2O and eaq-,another radiolysis products of water.Methanol and some mineral salts such as KCl,KBr inhibit the crosslinking to a certain extent.The mechanism of sensitization and inhibition is discussed in detail.
2003, 21(4): 465-472
Abstract:
Mycelium of a cultivated strain of Poria cocos was grown by submerged fermentation in a liquid mediumcontaining corn steep liquor with orbital shaking. Six polysaccharides coded as ac-PCM1, ac-PCM2, ac-PCM3-Ⅰ andⅡ, ac-PCM4-Ⅰand Ⅱ were isolated from the myelium by extracting with 0.9% NaCl aqueous solution, hot water, 0.5 mol/L NaOHaqueous solution and 88% formic acid. Exo-polysaccharide was obtained from the culture medium and coded as ac-PCM0.The monosaccharide composition and molecular weights of these polysaccharides were characterized by using infrared spectroscopy,gas chromatography,elemental analysis,13C-NMR,viscometry and light scattering.The results indicated that ac-PCM1,ac-PCM1 and ac-PCM2 are heteropolysaccharides containing glucose,galactose,mannose and fucose,and ac-PCM3-I and ac-PCM3-II mainly consist of D-glucose.The content of the glucose in the polysaccharides increased with the isolation progress.Remarkably,α-glucan and β-glucan coexisted in the extract by NaOH aqueous solution (ac-PCM3), and could be separated by chemical methods.The protein in the ac-PMC polysaccharides cultured from the medium containing corn steep liquor was higher than that in the ab-PCM from the medium with bran extract.Therefore,the polysaccharides from Poria cocos mycelia cultured in different media have different chemical composition,molecular weights and conformations.
Mycelium of a cultivated strain of Poria cocos was grown by submerged fermentation in a liquid mediumcontaining corn steep liquor with orbital shaking. Six polysaccharides coded as ac-PCM1, ac-PCM2, ac-PCM3-Ⅰ andⅡ, ac-PCM4-Ⅰand Ⅱ were isolated from the myelium by extracting with 0.9% NaCl aqueous solution, hot water, 0.5 mol/L NaOHaqueous solution and 88% formic acid. Exo-polysaccharide was obtained from the culture medium and coded as ac-PCM0.The monosaccharide composition and molecular weights of these polysaccharides were characterized by using infrared spectroscopy,gas chromatography,elemental analysis,13C-NMR,viscometry and light scattering.The results indicated that ac-PCM1,ac-PCM1 and ac-PCM2 are heteropolysaccharides containing glucose,galactose,mannose and fucose,and ac-PCM3-I and ac-PCM3-II mainly consist of D-glucose.The content of the glucose in the polysaccharides increased with the isolation progress.Remarkably,α-glucan and β-glucan coexisted in the extract by NaOH aqueous solution (ac-PCM3), and could be separated by chemical methods.The protein in the ac-PMC polysaccharides cultured from the medium containing corn steep liquor was higher than that in the ab-PCM from the medium with bran extract.Therefore,the polysaccharides from Poria cocos mycelia cultured in different media have different chemical composition,molecular weights and conformations.
2003, 21(4): 473-477
Abstract:
A kind of photosensitive ultra-thin film was fabricated from diazoresin (DR) and various calixarenes by using theself-assembly technique. Under UV irradiation both the ionic- and hydrogen bonds between the layers of the film will convert into covalent bonds. As a result, the stability of the film toward polar solvents increases dramatically.
A kind of photosensitive ultra-thin film was fabricated from diazoresin (DR) and various calixarenes by using theself-assembly technique. Under UV irradiation both the ionic- and hydrogen bonds between the layers of the film will convert into covalent bonds. As a result, the stability of the film toward polar solvents increases dramatically.
2003, 21(4): 479-481
Abstract:
Copolymerization of ethylene with carbon monoxide was pertormed with Cu catalyst systems. Novel catalystsystems based on Cu (Cu(CH3COO)2/ligand/acid) were firstly reported for the copolymerization of ethylene with carbonmonoxide, in which the ligand was a bidentate phosphorus chelating ligand. The experimental results showed that this kindof Cu catalyst system exhibited high activity. When DPPP (1, 3-bis(diphenylphosphine)propane) and CH3COOH were usedas ligand and acid, the corresponding catalyst system had the best activity of 108.1 g copolymer/(gCu·h).The novel Cu catalyst system had the advantages of high stability and low cost.
Copolymerization of ethylene with carbon monoxide was pertormed with Cu catalyst systems. Novel catalystsystems based on Cu (Cu(CH3COO)2/ligand/acid) were firstly reported for the copolymerization of ethylene with carbonmonoxide, in which the ligand was a bidentate phosphorus chelating ligand. The experimental results showed that this kindof Cu catalyst system exhibited high activity. When DPPP (1, 3-bis(diphenylphosphine)propane) and CH3COOH were usedas ligand and acid, the corresponding catalyst system had the best activity of 108.1 g copolymer/(gCu·h).The novel Cu catalyst system had the advantages of high stability and low cost.
EFFECTS OF PHENOL RESIN ADDITIVE ON DYNAMIC MECHANICAL PROPERTIES OF ACRYLATE RUBBER AND ITS BLENDS*
2003, 21(4): 483-486
Abstract:
The dynamic mechanical properties of a new blend system consisting of phenol resin and polar polymer (acrylaterubber and/or chlorinated polypropylene) were investigated. It was found that the addition of phenol resin to acrylate rubberand its incompatible blend can cause a remarkable improvement in the temperature dependence of the loss tangent. As a result, the present blends are very good damping materials.
The dynamic mechanical properties of a new blend system consisting of phenol resin and polar polymer (acrylaterubber and/or chlorinated polypropylene) were investigated. It was found that the addition of phenol resin to acrylate rubberand its incompatible blend can cause a remarkable improvement in the temperature dependence of the loss tangent. As a result, the present blends are very good damping materials.
