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2003 Volume 21 Issue 3
2003, 21(3): 265-270
Abstract:
Two new chiral ionic liquids, 1 -((-)-menthoxycarbonylmethylene)-3-methylimidazolium hexafluorophosphateand 1-((-)-menthoxycarbonylmethylene)-3-hexadecylimidazolium hexafluorophosphate, were designed an d prepared. Theirchemical structures were characterized by 1H-NMR. Reverse atom transfer radical polymerization of methyl methacrylate(MMA) in these two ionic liquids was carried out using AIBN/CuCl2/bipy as the initiating system. The resultant well-definedpolymethyl methacrylate (PMMA) was employed as a macroinitiator to induce the atom transfer radical polymerization of menthyl methacrylate(MnMA) in chlorobenzene,which yieded a PMMA-b-PMnMA diblock copolymer with narrow polydispersity.
Two new chiral ionic liquids, 1 -((-)-menthoxycarbonylmethylene)-3-methylimidazolium hexafluorophosphateand 1-((-)-menthoxycarbonylmethylene)-3-hexadecylimidazolium hexafluorophosphate, were designed an d prepared. Theirchemical structures were characterized by 1H-NMR. Reverse atom transfer radical polymerization of methyl methacrylate(MMA) in these two ionic liquids was carried out using AIBN/CuCl2/bipy as the initiating system. The resultant well-definedpolymethyl methacrylate (PMMA) was employed as a macroinitiator to induce the atom transfer radical polymerization of menthyl methacrylate(MnMA) in chlorobenzene,which yieded a PMMA-b-PMnMA diblock copolymer with narrow polydispersity.
2003, 21(3): 271-276
Abstract:
Ferrofluid containing highly conductive polyaniline (PANI) was prepared, in which soluble PANI solutions dopedwith 10-camphorsulfonic acid (CSA) and dodecyl benzenesulfonic acid (DBSA) were used as the basic solution and Fe3O4nanoparticles (d = 10 nm) as the magnetic material. Moreover, the freestanding films of the resulting ferrofluid can beobtained by an evaporation method. The electrical and magnetic properties of the ferrofluid or its films can be adjusted through changing the content of PANI and Fe3O4.High saturated magnetization (≈ 30 emu/g) and high conductivity (≈250 S/cm) of thecomposite films can be achieved when the composite film contains 26.6 wt% of Fe3O4.In particular,it was found that the composite films exhibit a super-paramagnetic behavior(Hc=0)attributed to the size of Fe3O4 particles on the nanometer scale.
Ferrofluid containing highly conductive polyaniline (PANI) was prepared, in which soluble PANI solutions dopedwith 10-camphorsulfonic acid (CSA) and dodecyl benzenesulfonic acid (DBSA) were used as the basic solution and Fe3O4nanoparticles (d = 10 nm) as the magnetic material. Moreover, the freestanding films of the resulting ferrofluid can beobtained by an evaporation method. The electrical and magnetic properties of the ferrofluid or its films can be adjusted through changing the content of PANI and Fe3O4.High saturated magnetization (≈ 30 emu/g) and high conductivity (≈250 S/cm) of thecomposite films can be achieved when the composite film contains 26.6 wt% of Fe3O4.In particular,it was found that the composite films exhibit a super-paramagnetic behavior(Hc=0)attributed to the size of Fe3O4 particles on the nanometer scale.
2003, 21(3): 277-283
Abstract:
In this paper, the surface structure of poly(L-lactic acid) (PLLA) film modified with gelatin was investigated. ThePLLA film specimens were treated directly with aqueous alkali solution to provide their surfaces with carboxyl groups, sothat these functional groups could become the reactive sites for gelatin immobilization. The functional groups of the PLLAfilms were identified by ATR-FTIR spectra and XPS spectra, the changes in surface morphology were observed by using environmental scanning electron microscopy(ESEM),and the hydrophilicity of modified PLLA films was examined by water contact angle measurement.Experimental results showed that the gelatin was immobilized with water-soluble carbodiimide (EDC) onto the PLLA film's surfaces,and the gelatin content on the polymer surface was related to carboxylic group formed in the controlled hydrolysis process.Rough surfaces caused by hydrolysis will predominantly favor the adhesion and growth of cell;and the hydrophilicity of these surfaces after the modification procedure is enhanced.
In this paper, the surface structure of poly(L-lactic acid) (PLLA) film modified with gelatin was investigated. ThePLLA film specimens were treated directly with aqueous alkali solution to provide their surfaces with carboxyl groups, sothat these functional groups could become the reactive sites for gelatin immobilization. The functional groups of the PLLAfilms were identified by ATR-FTIR spectra and XPS spectra, the changes in surface morphology were observed by using environmental scanning electron microscopy(ESEM),and the hydrophilicity of modified PLLA films was examined by water contact angle measurement.Experimental results showed that the gelatin was immobilized with water-soluble carbodiimide (EDC) onto the PLLA film's surfaces,and the gelatin content on the polymer surface was related to carboxylic group formed in the controlled hydrolysis process.Rough surfaces caused by hydrolysis will predominantly favor the adhesion and growth of cell;and the hydrophilicity of these surfaces after the modification procedure is enhanced.
2003, 21(3): 285-289
Abstract:
A method of estimating the critical rate of temperature increase of thermal explosion for the first orderautocatalytic decomposition reaction system using non-isothermal DSC is presented. Information is obtained on theincreasing rate of temperature in nitrocellulose containing 13.54% of nitrogen when the first order autocatalytic decomposition converts into thermal explosion.
A method of estimating the critical rate of temperature increase of thermal explosion for the first orderautocatalytic decomposition reaction system using non-isothermal DSC is presented. Information is obtained on theincreasing rate of temperature in nitrocellulose containing 13.54% of nitrogen when the first order autocatalytic decomposition converts into thermal explosion.
2003, 21(3): 291-296
Abstract:
By using a two-stage soapless emulsion polymerization, four kinds of core-shell nanoparticles have been prepared,which are composed of a polystyrene core having an average diameter of 256 nm and a poly(methyl methacrylate-co-acrylicacid) shell. The transmission electron microscopy (TEM) micrographs and the atomic force microscopy (AFM) imagesevidenced the presence of a core-shell structure. In the infrared spectra, the shift of vCOOH to lower wavenumber withincreasing Eu3+ ion content indicates that coordination between the oxygen of the carboxylic group and Eu3+ has occurred.The fluorescence intensity of 5D0-7F2 transition was observed to reach its maximum with a carboxyl group molar percentage of 40% in the shell and an Eu3+/—COO- molar ratio of 1:3.The fluorescence intensity ratio of 5D0-7F2 to 5D0-7F1 transition reached its maximum with an Eu3+/—COO- molar ratio of 1:3 for all the four series.
By using a two-stage soapless emulsion polymerization, four kinds of core-shell nanoparticles have been prepared,which are composed of a polystyrene core having an average diameter of 256 nm and a poly(methyl methacrylate-co-acrylicacid) shell. The transmission electron microscopy (TEM) micrographs and the atomic force microscopy (AFM) imagesevidenced the presence of a core-shell structure. In the infrared spectra, the shift of vCOOH to lower wavenumber withincreasing Eu3+ ion content indicates that coordination between the oxygen of the carboxylic group and Eu3+ has occurred.The fluorescence intensity of 5D0-7F2 transition was observed to reach its maximum with a carboxyl group molar percentage of 40% in the shell and an Eu3+/—COO- molar ratio of 1:3.The fluorescence intensity ratio of 5D0-7F2 to 5D0-7F1 transition reached its maximum with an Eu3+/—COO- molar ratio of 1:3 for all the four series.
2003, 21(3): 297-302
Abstract:
The interaction between surfactants and fluorocarbon-modified polyacrylamide (FC-PAM) in aqueous solutionswas evaluated by rheological means and fluorescence spectroscopy and was found to be strong regardless of the surfactant'snature. Two representative surfactants, anionic sodium dodecyl sulfate (SDS) and nonionic Triton X-100, were used. The origin of the interaction and its dependence on the surfactant concentration were discussed.
The interaction between surfactants and fluorocarbon-modified polyacrylamide (FC-PAM) in aqueous solutionswas evaluated by rheological means and fluorescence spectroscopy and was found to be strong regardless of the surfactant'snature. Two representative surfactants, anionic sodium dodecyl sulfate (SDS) and nonionic Triton X-100, were used. The origin of the interaction and its dependence on the surfactant concentration were discussed.
2003, 21(3): 303-308
Abstract:
Microstructures were produced on curved surfaces and micro-protrusions by using direct micromolding with fourthermoplastic polymers. This method is simpler and more convenient than micromolding with liquid prepolymer or using theμTM method. By repeated molding, crossed structures were produced with a stamp prepared only with lines. The processingvariables including the softening temperature of the polymers and heating time were discussed. The result shows that the optimal molding temperature is preferably slightly higher than the melting temperature of the thermoplastic polymers,at which polymers are in the critical states of being melted.This method can be applied to many polymers except those with high softening temperatures or high rate of shrinkage upon temperature change.
Microstructures were produced on curved surfaces and micro-protrusions by using direct micromolding with fourthermoplastic polymers. This method is simpler and more convenient than micromolding with liquid prepolymer or using theμTM method. By repeated molding, crossed structures were produced with a stamp prepared only with lines. The processingvariables including the softening temperature of the polymers and heating time were discussed. The result shows that the optimal molding temperature is preferably slightly higher than the melting temperature of the thermoplastic polymers,at which polymers are in the critical states of being melted.This method can be applied to many polymers except those with high softening temperatures or high rate of shrinkage upon temperature change.
2003, 21(3): 309-316
Abstract:
Six water-soluble polysaccharide-protein complexes coded as GM1, GM2, GM3, GM4, GM5 and GM6 wereisolated from the mycelium of Ganoderma tsugae by extracting with 0.2 mol/L phosphate buffer solution at 25, 40 and80℃, water at 120℃, 0.5 mol/L aqueous NaOH solution at 25 and 65℃, consecutively. Their chemical components wereanalyzed by using IR, GC, HPLC and 13C-NMR, and some new results were obtained. The four samples GM1, GM2, GM3 and GM4 are heteropolysaccharide-prote in complexes, in which, α- (1→3) linked D-glucose is the major monosaccharide while galactose,mannose and ribose are the secondary ones.GM5 and GM6 are β-(1→3)-D-glucan-protein complexes.The protein content increased from 32% to 69% with the progress of isolation.Weight-average molecular mass Mw and the intrinsic viscosity [η] of the GM samples in 0.5mol/L aqueous NaCl solution at 25℃ were measured systematically by laser light scattering (LLS),size exclusion chromatography(SEC) combined with LLS,and viscometry.The Mw of GMI to GM6 are 35.5,46.8,58.9,41.6,3.3 and 22.0×104,respectively.The conformation and molecular mass of the two fractions of sample GM5 were characterized satisfactorily by SEC-LLS without further fractionation.
Six water-soluble polysaccharide-protein complexes coded as GM1, GM2, GM3, GM4, GM5 and GM6 wereisolated from the mycelium of Ganoderma tsugae by extracting with 0.2 mol/L phosphate buffer solution at 25, 40 and80℃, water at 120℃, 0.5 mol/L aqueous NaOH solution at 25 and 65℃, consecutively. Their chemical components wereanalyzed by using IR, GC, HPLC and 13C-NMR, and some new results were obtained. The four samples GM1, GM2, GM3 and GM4 are heteropolysaccharide-prote in complexes, in which, α- (1→3) linked D-glucose is the major monosaccharide while galactose,mannose and ribose are the secondary ones.GM5 and GM6 are β-(1→3)-D-glucan-protein complexes.The protein content increased from 32% to 69% with the progress of isolation.Weight-average molecular mass Mw and the intrinsic viscosity [η] of the GM samples in 0.5mol/L aqueous NaCl solution at 25℃ were measured systematically by laser light scattering (LLS),size exclusion chromatography(SEC) combined with LLS,and viscometry.The Mw of GMI to GM6 are 35.5,46.8,58.9,41.6,3.3 and 22.0×104,respectively.The conformation and molecular mass of the two fractions of sample GM5 were characterized satisfactorily by SEC-LLS without further fractionation.
2003, 21(3): 317-324
Abstract:
The adsorption behavior of benzoic acid onto a water-compatible hypercrosslinked polymeric adsorbent NJ-8 wascompared with that onto macroporous Amberlite XAN-4. This paper focuses on the static equilibrium adsorption behaviors,the adsorption thermodynamics and the column dynamic adsorption profiles. Five isotherm models are used to fit the results.This shows that the Freundlich equation can give a perfect fit. The specific surface area of NJ-8 is about as high as that ofAmberlite XAD-4, but the adsorbing capacity for benzoic acid on NJ-8 is about 14.9%-64.8% higher than that on Amberlite XAD-4,which is attributed to its microporous mechanism and partial polarity.The negative values of the adsorption enthalpy are indicative of an exothermic process.Both enthalpy and free energy changes of adsorption manifest a physical sorption process.The negative values of the adsorption entropy indicate that adsorption is well consistent with the restricted mobilities and the configurations of the adsorbed molecules on the surface of the studied adsorbents with superficial heterogeneity.Both adsorbents were used in mini-colum experiments to demonstrate the higher breakthrough adsorbing capacity of the hypercrosslinked polymeric adsorbent NJ-8 to benzoic acid,as compared with that of AMberlite XAD-4.
The adsorption behavior of benzoic acid onto a water-compatible hypercrosslinked polymeric adsorbent NJ-8 wascompared with that onto macroporous Amberlite XAN-4. This paper focuses on the static equilibrium adsorption behaviors,the adsorption thermodynamics and the column dynamic adsorption profiles. Five isotherm models are used to fit the results.This shows that the Freundlich equation can give a perfect fit. The specific surface area of NJ-8 is about as high as that ofAmberlite XAD-4, but the adsorbing capacity for benzoic acid on NJ-8 is about 14.9%-64.8% higher than that on Amberlite XAD-4,which is attributed to its microporous mechanism and partial polarity.The negative values of the adsorption enthalpy are indicative of an exothermic process.Both enthalpy and free energy changes of adsorption manifest a physical sorption process.The negative values of the adsorption entropy indicate that adsorption is well consistent with the restricted mobilities and the configurations of the adsorbed molecules on the surface of the studied adsorbents with superficial heterogeneity.Both adsorbents were used in mini-colum experiments to demonstrate the higher breakthrough adsorbing capacity of the hypercrosslinked polymeric adsorbent NJ-8 to benzoic acid,as compared with that of AMberlite XAD-4.
2003, 21(3): 325-332
Abstract:
Positron lifetime measurements have been made in natural polymer-Nistari silk fibers as a function of isochronalannealing temperature in the range of 27℃ to 280℃. The variations in the positron results indicate the structural changesoccurring in the Nistari silk fibers and determine the glass transition temperature as 170℃. Activation energies weremeasured separately for the crystalline and amorphous regions indicating the versatility of the technique. These values areclose to the N--H bond dissociation energy,suggesting N—H bond dissociation as the most probable process occurring during thermal treatment.As an extension of the positron results,the molecular weight of the Nistari silk fibers was determined to be 10.7×105 based on free volume,which lies within the range suggested for the silk fibers.There seems to be an indication that cross-linking changes the spiral structure of cotton fibers to network type.However,this needs to be validated by other techniques.
Positron lifetime measurements have been made in natural polymer-Nistari silk fibers as a function of isochronalannealing temperature in the range of 27℃ to 280℃. The variations in the positron results indicate the structural changesoccurring in the Nistari silk fibers and determine the glass transition temperature as 170℃. Activation energies weremeasured separately for the crystalline and amorphous regions indicating the versatility of the technique. These values areclose to the N--H bond dissociation energy,suggesting N—H bond dissociation as the most probable process occurring during thermal treatment.As an extension of the positron results,the molecular weight of the Nistari silk fibers was determined to be 10.7×105 based on free volume,which lies within the range suggested for the silk fibers.There seems to be an indication that cross-linking changes the spiral structure of cotton fibers to network type.However,this needs to be validated by other techniques.
2003, 21(3): 333-338
Abstract:
The morphology of PE in the in-situ CB/PE composites prepared from in-situ polymerization via a catalyst-supported approach was studied by DSC. It is found that both the melting peak temperature and crystallinity of the PE shelldecrease as filler level increases. The unexpected phenomena are ascribed to the strong interaction between PE and CB andthe very high specific area of CB. It is suggested that the lamellar thickness should be well correlated to the PE shell thickness. A two-layer PE model is successfully used to explain the experiment results.
The morphology of PE in the in-situ CB/PE composites prepared from in-situ polymerization via a catalyst-supported approach was studied by DSC. It is found that both the melting peak temperature and crystallinity of the PE shelldecrease as filler level increases. The unexpected phenomena are ascribed to the strong interaction between PE and CB andthe very high specific area of CB. It is suggested that the lamellar thickness should be well correlated to the PE shell thickness. A two-layer PE model is successfully used to explain the experiment results.
2003, 21(3): 339-346
Abstract:
Two highly cross-linked superfine styrene-butadiene rubber particles, one with 1 wt% of carboxyl groups and theother without such groups having particle sizes of 130-150 nm and 80-100 nm respectively, were used to prepare nylon6/rubber composites via in situ polymerization. It was found that carboxylic styrene-butadiene dispersed uniformly in nylonmatrix and there was strong interfacial interaction because of the graft polymer formed by the reaction of nylon with carboxylgroup of the rubber, resulting in considerably improved impact strength with almost unchanged tensile strngth.However,the addition of styrene-butadiene without carboxyl groups showed intensive agglomeration of the rubber particles and weak interfacial interactions,and the toughness of the materials was improved slightly.The crystallization and rheological behavior of the composites were also discussed.
Two highly cross-linked superfine styrene-butadiene rubber particles, one with 1 wt% of carboxyl groups and theother without such groups having particle sizes of 130-150 nm and 80-100 nm respectively, were used to prepare nylon6/rubber composites via in situ polymerization. It was found that carboxylic styrene-butadiene dispersed uniformly in nylonmatrix and there was strong interfacial interaction because of the graft polymer formed by the reaction of nylon with carboxylgroup of the rubber, resulting in considerably improved impact strength with almost unchanged tensile strngth.However,the addition of styrene-butadiene without carboxyl groups showed intensive agglomeration of the rubber particles and weak interfacial interactions,and the toughness of the materials was improved slightly.The crystallization and rheological behavior of the composites were also discussed.
2003, 21(3): 347-351
Abstract:
PP can be included in the cavities of cyclodextrin (CD). The crystalline inclusion complex between β-CD and lowmolecular weight polypropylene (PP) was obtained and investigated. α-CD and γ-CD did not form crystalline inclusioncomplexes with PP. The FTIR spectra, TGA, X-ray diffraction spectra were studied, 1H-NMR spectra and13C CP/MAS NMR spectra were used to characterize the crystalline inclusion complexes.
PP can be included in the cavities of cyclodextrin (CD). The crystalline inclusion complex between β-CD and lowmolecular weight polypropylene (PP) was obtained and investigated. α-CD and γ-CD did not form crystalline inclusioncomplexes with PP. The FTIR spectra, TGA, X-ray diffraction spectra were studied, 1H-NMR spectra and13C CP/MAS NMR spectra were used to characterize the crystalline inclusion complexes.
2003, 21(3): 353-357
Abstract:
The interaction of poly(sodium sulfodecyl methacrylate) (PSSM) with cetyltrimethyl ammonium bromide (CTAB)was studied. It was found that the precipitate formed from PSSM and CTAB will be dissolved by excessive CTAB, resultingin the appearance of two maxima of the solution viscosity at the molar ratio (CTAB/-SO3-) of≈ 0.68 and≈1.30,respectively. The first one is related closely to the aggregation of polymer chains via CTAB molecules and the second oneshould be ascribed to the formation of the mixed micelles comprising surfactant and the polymer's hydrophobic chains.The effect of NaCl on the viscosity,the transmittance of the aqueous solution and the solubility of oil-soluble dye (dimethyl yellow) in the mixed system were also investigated.
The interaction of poly(sodium sulfodecyl methacrylate) (PSSM) with cetyltrimethyl ammonium bromide (CTAB)was studied. It was found that the precipitate formed from PSSM and CTAB will be dissolved by excessive CTAB, resultingin the appearance of two maxima of the solution viscosity at the molar ratio (CTAB/-SO3-) of≈ 0.68 and≈1.30,respectively. The first one is related closely to the aggregation of polymer chains via CTAB molecules and the second oneshould be ascribed to the formation of the mixed micelles comprising surfactant and the polymer's hydrophobic chains.The effect of NaCl on the viscosity,the transmittance of the aqueous solution and the solubility of oil-soluble dye (dimethyl yellow) in the mixed system were also investigated.
2003, 21(3): 359-367
Abstract:
Most of the anicles on polymer nanocomposites focus on the importance of chemistry used to modify the surfaceof the clay, usually montmorillonite (MMT), and characterization of the nano-scale structure obtained. The role andimportance of processing were also discussed recently. However, few papers concerning the correlation between morphologyof MMT and mechanical properties were published. In order to understand the tensile behavior of PP/Montmorillonite(MMT) nanocomposites better, and to further improve the reinforcement efficiency,we first prepared the PP nanocomposites via direct melt intercalation using conventional twin-screw extrusion.The dispersion and tensile property of the composites were then investigated by SEM,XRD,TEM and a video-controlled tensile set-up.The macroscopic and microscopic dispersion of MMT in PP matrix was verified by XRD and TEM,combined with SEM.The tensile properties were obtained by video-controlled tensile set-up,which gives true stress-strain curve.It was found that a partly intercalated and partly exfoliated structure (also called incomplete exfoliation) existed in the system.Though the tensile strength of PP nanocomposites is not much improved in engineering stress-strain curves,more than 20% increase of true stress was found in a true stress-strain experiment at high true strain,which indicates that only oriented silicate layers can have a big effect on tensile properties.Not only orientation of silicate platelets but also the degree of exfoliation is a key factor to determine the reinforcement efficiency.The reinforcement efficiency of MMT has been discussed based on the"continuum" Halpin-Tsaiequations.A good agreement was found between experimental data and theoretical prediction by changing N value(number of platelets per stack) which corresponding to different state of the dispersion of MMT in PP matrix.
Most of the anicles on polymer nanocomposites focus on the importance of chemistry used to modify the surfaceof the clay, usually montmorillonite (MMT), and characterization of the nano-scale structure obtained. The role andimportance of processing were also discussed recently. However, few papers concerning the correlation between morphologyof MMT and mechanical properties were published. In order to understand the tensile behavior of PP/Montmorillonite(MMT) nanocomposites better, and to further improve the reinforcement efficiency,we first prepared the PP nanocomposites via direct melt intercalation using conventional twin-screw extrusion.The dispersion and tensile property of the composites were then investigated by SEM,XRD,TEM and a video-controlled tensile set-up.The macroscopic and microscopic dispersion of MMT in PP matrix was verified by XRD and TEM,combined with SEM.The tensile properties were obtained by video-controlled tensile set-up,which gives true stress-strain curve.It was found that a partly intercalated and partly exfoliated structure (also called incomplete exfoliation) existed in the system.Though the tensile strength of PP nanocomposites is not much improved in engineering stress-strain curves,more than 20% increase of true stress was found in a true stress-strain experiment at high true strain,which indicates that only oriented silicate layers can have a big effect on tensile properties.Not only orientation of silicate platelets but also the degree of exfoliation is a key factor to determine the reinforcement efficiency.The reinforcement efficiency of MMT has been discussed based on the"continuum" Halpin-Tsaiequations.A good agreement was found between experimental data and theoretical prediction by changing N value(number of platelets per stack) which corresponding to different state of the dispersion of MMT in PP matrix.
2003, 21(3): 369-371
Abstract:
Poly(4-methyl-1-pentene) (PMP) hollow fiber membranes were prepared by the melt-spun and cold-stretch(MSCS) method. Scanning electronic microscopy (SEM) was used to characterize the section and surface structures of themembranes with special asymmetric structure. The preliminary results of gas permeation measurements indicated that the resultant hollow fiber membranes have the potential ability for oxygen/nitrogen separation.
Poly(4-methyl-1-pentene) (PMP) hollow fiber membranes were prepared by the melt-spun and cold-stretch(MSCS) method. Scanning electronic microscopy (SEM) was used to characterize the section and surface structures of themembranes with special asymmetric structure. The preliminary results of gas permeation measurements indicated that the resultant hollow fiber membranes have the potential ability for oxygen/nitrogen separation.
2003, 21(3): 373-375
Abstract:
In this work, the surface properties of novel sugar-containing polymers, α-allyl glucoside (AG)/acrylonitrile (AN)copolymers, were studied by contact angle, protein adsorption and cell adhesion measurements. It was found that the contactangle of the copolymer films decreased from 68° to 30° with the increase of AG content in the copolymer. The adsorptionamount of bovine serum albumin (BSA) and the adhesive macrophage onto the film surface also decreased significantly withincreasing α-allyl glucoside content from 0 to 42 wt% in the copolymer.These preliminary results reveal that both the hydrophilicity and the biocompatibility of polyacrylonitrile-based membranes could be improved by copolymerizing acrylonitrile with vinyl carbohydrates.
In this work, the surface properties of novel sugar-containing polymers, α-allyl glucoside (AG)/acrylonitrile (AN)copolymers, were studied by contact angle, protein adsorption and cell adhesion measurements. It was found that the contactangle of the copolymer films decreased from 68° to 30° with the increase of AG content in the copolymer. The adsorptionamount of bovine serum albumin (BSA) and the adhesive macrophage onto the film surface also decreased significantly withincreasing α-allyl glucoside content from 0 to 42 wt% in the copolymer.These preliminary results reveal that both the hydrophilicity and the biocompatibility of polyacrylonitrile-based membranes could be improved by copolymerizing acrylonitrile with vinyl carbohydrates.
2003, 21(3): 377-380
Abstract:
A new azobenzene side-chain polymer (TEMPO-PAZ) containing TEMPO (4-hydroxy-2, 2, 6, 6-tetramethyl-piperidinooxy) radical end group was synthesized by free radical copolymerization. Photoinduced alignment was studied onthe polymer films at room temperature with linearly polarized light of 514.5 nm, The experimental results showed that themagnetic response intensity of the TEMPO-PAZ could be easily controlled by choosing the appropriate polarized light irradiating times, presumably due to the nitroxide radical in the TEMPO-PAZ molecular structure.For the polymer investigated here,the photoinduced alignment technique was introduced to increase the magnetic response intensity of polymer under irradiation,aiming originally at searching for a new photo-active organic magnetic multifunctional materials.On the other hand,experimental results also showed that the TEMPO-PAZ can be used as a material for optical image storage.
A new azobenzene side-chain polymer (TEMPO-PAZ) containing TEMPO (4-hydroxy-2, 2, 6, 6-tetramethyl-piperidinooxy) radical end group was synthesized by free radical copolymerization. Photoinduced alignment was studied onthe polymer films at room temperature with linearly polarized light of 514.5 nm, The experimental results showed that themagnetic response intensity of the TEMPO-PAZ could be easily controlled by choosing the appropriate polarized light irradiating times, presumably due to the nitroxide radical in the TEMPO-PAZ molecular structure.For the polymer investigated here,the photoinduced alignment technique was introduced to increase the magnetic response intensity of polymer under irradiation,aiming originally at searching for a new photo-active organic magnetic multifunctional materials.On the other hand,experimental results also showed that the TEMPO-PAZ can be used as a material for optical image storage.
2003, 21(3): 381-384
Abstract:
The anodic porous alumina membranes with a definite pore diameter and aspect ratio were used as templates tosynthesize polymer pillared layer structures. The pillared polymer was produced in the template membrane pores, and thelayer on the template surfaces. Rigid cured epoxy resin, polystyrene and soft hydrogel were chosen to confirm themethodology. The pillars were in the form of either tubes or fibers, which were controlled by the alumina membrane pore surface wettability. The structural features were confirmed by scanning electron microscopy results.
The anodic porous alumina membranes with a definite pore diameter and aspect ratio were used as templates tosynthesize polymer pillared layer structures. The pillared polymer was produced in the template membrane pores, and thelayer on the template surfaces. Rigid cured epoxy resin, polystyrene and soft hydrogel were chosen to confirm themethodology. The pillars were in the form of either tubes or fibers, which were controlled by the alumina membrane pore surface wettability. The structural features were confirmed by scanning electron microscopy results.
