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2000 Volume 18 Issue 2
2000, 18(2): 95-99
Abstract:
A variety of mesomorphic side-chain polysiloxanes were synthesized by using hydrosilylation reaction withdicyclopentadienylplatinum (Ⅱ) (DPPC) as the catalyst. The mesogenic groups are derivatives of stilbene with cyano or nitrotail groups. The products were characterized by DSC, X-ray deffraction and polarizing optical microscopy (POM). All thepolymers were found to have relatively low Tg and can form a smectic liquid crystal phase.
A variety of mesomorphic side-chain polysiloxanes were synthesized by using hydrosilylation reaction withdicyclopentadienylplatinum (Ⅱ) (DPPC) as the catalyst. The mesogenic groups are derivatives of stilbene with cyano or nitrotail groups. The products were characterized by DSC, X-ray deffraction and polarizing optical microscopy (POM). All thepolymers were found to have relatively low Tg and can form a smectic liquid crystal phase.
2000, 18(2): 101-107
Abstract:
Novel side-chain liquid-crystalline poly(meth)acrylates were synthesized using 1-(3-hydroxyl-propyl)-3-[(4"-cyano-p-terphenyloxycarbonyl)alkyl]-1,1,3,3-tetramethyldisiloxane as the key intermediate. The polymers used a disiloxanemoiety as decoupling spacer with cyano-p-terphenyl as mesogenic unit. The products were characterized by NMR, GPC,DSC and polarizing optical microscopy. All the polymers with cyano-p-terphenyl mesogens formed a stable mesophase.However, if the mesogenic unit is replaced by cyano-p-biphenyl,the liquid crystalline character will be lost.The results also showed that the decoupling is incomplete even if a complex and very flexible decoupling spacer is deliberately incorporated to obtain the highest possible decoupling effect.
Novel side-chain liquid-crystalline poly(meth)acrylates were synthesized using 1-(3-hydroxyl-propyl)-3-[(4"-cyano-p-terphenyloxycarbonyl)alkyl]-1,1,3,3-tetramethyldisiloxane as the key intermediate. The polymers used a disiloxanemoiety as decoupling spacer with cyano-p-terphenyl as mesogenic unit. The products were characterized by NMR, GPC,DSC and polarizing optical microscopy. All the polymers with cyano-p-terphenyl mesogens formed a stable mesophase.However, if the mesogenic unit is replaced by cyano-p-biphenyl,the liquid crystalline character will be lost.The results also showed that the decoupling is incomplete even if a complex and very flexible decoupling spacer is deliberately incorporated to obtain the highest possible decoupling effect.
2000, 18(2): 109-113
Abstract:
Solvent-free polymeric alkali-metal ion conductors, consisting of a comb-like polysiloxane with oligo(oxy-ethylene) side chains and pendant sulfate groups were synthesized by the hydrosilylation of allyl oligo(oxyethylene) sulfatesalt and allyl methoxy oligo(oxyethylene) with poly(methylhydrosiloxane). The factors influncing the ionic conductivity ofthe resulting polymer such as the electrolyte content and the nature of the alkali-metal were investigated. The temperature dependence of conductivity was determined,and the ionic conductivity of the polymer follows the Vogel-Tammann-Fulcher (VTF) equation.
Solvent-free polymeric alkali-metal ion conductors, consisting of a comb-like polysiloxane with oligo(oxy-ethylene) side chains and pendant sulfate groups were synthesized by the hydrosilylation of allyl oligo(oxyethylene) sulfatesalt and allyl methoxy oligo(oxyethylene) with poly(methylhydrosiloxane). The factors influncing the ionic conductivity ofthe resulting polymer such as the electrolyte content and the nature of the alkali-metal were investigated. The temperature dependence of conductivity was determined,and the ionic conductivity of the polymer follows the Vogel-Tammann-Fulcher (VTF) equation.
2000, 18(2): 115-122
Abstract:
The reverse osmosis (RO) separation of aqueous organic solutions, such as alcohols, amines, aldehydes, acids,ketones, and esters etc., by PAA (polyacrylic acid)/PSF (polysulfone) composite membrane has been studied. It was foundthat the separation results for aliphatic alcohols, amines and aldehydes are satisfactory, the solute rejection (Ra) and thevolume fluxes of solutions (Jv) for 1000 ppm ethanol, ethylamine and ethyl aldehyde are 66.2%, 61.0%, 84.0% and 0.90×10-6, 0.35×10-6, 0.40×10-6m3/m2·s,respectively,at 5.0 MPa and ℃.Ra increased with increasing molecular weights of alcohols,amines and aldehydes,and the Ra for n-amyl alcohol,n-butylamine and n-butyl aldehyde reached 94.3%,88.6% and 96.0%,respectively.Satisfactory separation results (Ra>70%) for ketones,esters,phenols and polyols have been obtained with the PAA/PSF composite membrane.The effect of operating pressure on the properties of reverse osmosis has also been investigated.Analysis of experimental data with Spiegler-Kedem's transport model has been carried out and the membrane constants such as reflection coefficient σ,solute and hydraulic permeabilities ω and Lp for several organic solutes have been obtained.
The reverse osmosis (RO) separation of aqueous organic solutions, such as alcohols, amines, aldehydes, acids,ketones, and esters etc., by PAA (polyacrylic acid)/PSF (polysulfone) composite membrane has been studied. It was foundthat the separation results for aliphatic alcohols, amines and aldehydes are satisfactory, the solute rejection (Ra) and thevolume fluxes of solutions (Jv) for 1000 ppm ethanol, ethylamine and ethyl aldehyde are 66.2%, 61.0%, 84.0% and 0.90×10-6, 0.35×10-6, 0.40×10-6m3/m2·s,respectively,at 5.0 MPa and ℃.Ra increased with increasing molecular weights of alcohols,amines and aldehydes,and the Ra for n-amyl alcohol,n-butylamine and n-butyl aldehyde reached 94.3%,88.6% and 96.0%,respectively.Satisfactory separation results (Ra>70%) for ketones,esters,phenols and polyols have been obtained with the PAA/PSF composite membrane.The effect of operating pressure on the properties of reverse osmosis has also been investigated.Analysis of experimental data with Spiegler-Kedem's transport model has been carried out and the membrane constants such as reflection coefficient σ,solute and hydraulic permeabilities ω and Lp for several organic solutes have been obtained.
2000, 18(2): 123-128
Abstract:
Positron annihilation spectroscopy (PAS) was utilized to investigate the relationship between the free-volume holeproperties and miscibility of dynamically vulcanized EPDM/PP blend. The results showed that the noncrystalline region ofPP and EPDM in the blend was partially miscible and the miscibility of the blend became worse when the weight percent ofEPDM was <50%. This was also demonstrated by DMTA and mechanical properties of the blends with variouscompositions.
Positron annihilation spectroscopy (PAS) was utilized to investigate the relationship between the free-volume holeproperties and miscibility of dynamically vulcanized EPDM/PP blend. The results showed that the noncrystalline region ofPP and EPDM in the blend was partially miscible and the miscibility of the blend became worse when the weight percent ofEPDM was <50%. This was also demonstrated by DMTA and mechanical properties of the blends with variouscompositions.
2000, 18(2): 129-132
Abstract:
In this paper, the synthesis and crystallization behavior of poly(ether ether ketone ether ketone) (PEEKEK) arereported. PEEKEK was prepared from 4,4'-bis(p-fluorobenzoyl) diphenyl ether (4,4'-FBDE) and hydroquinone along thenucleophilic substitution route. The thermal properties were investigated by using DSC and TGA. The crystallizationbehavior of PEEKEK under several conditions, i.e., crystallization from the molten state (melt crystallization), crystallizationfrom a quenched sample (cold crystallization) and crystallization induced by exposing glassy sample to methylene chloride(solvent-induced crystallization) has also been investigated.The results show that crystallization of PEEKEK could be induced by the above methods,and no polymorphism was found. The differences in the crystallization of PEEKEK induced by the above methods are seen in their degree of crystallinity.
In this paper, the synthesis and crystallization behavior of poly(ether ether ketone ether ketone) (PEEKEK) arereported. PEEKEK was prepared from 4,4'-bis(p-fluorobenzoyl) diphenyl ether (4,4'-FBDE) and hydroquinone along thenucleophilic substitution route. The thermal properties were investigated by using DSC and TGA. The crystallizationbehavior of PEEKEK under several conditions, i.e., crystallization from the molten state (melt crystallization), crystallizationfrom a quenched sample (cold crystallization) and crystallization induced by exposing glassy sample to methylene chloride(solvent-induced crystallization) has also been investigated.The results show that crystallization of PEEKEK could be induced by the above methods,and no polymorphism was found. The differences in the crystallization of PEEKEK induced by the above methods are seen in their degree of crystallinity.
2000, 18(2): 133-138
Abstract:
Polysiloxane-modified epoxy resins were prepared through the reaction of epoxy resin with polydimethylsiloxanesbearing pendant N-(β-aminoethyl)-γ-aminopropyl groups. The morphology and properties of the cured epoxy resins modifiedby the polysiloxanes were investigated. It was found that the phase structure and properties of the cured epoxy resins dependmainly on the amino group content in the polydimethylsiloxane and the level of the modifier. The change of phase structure in the cured epoxy resin systems was responsible for the dramatic change in their mechanical and surface properties.
Polysiloxane-modified epoxy resins were prepared through the reaction of epoxy resin with polydimethylsiloxanesbearing pendant N-(β-aminoethyl)-γ-aminopropyl groups. The morphology and properties of the cured epoxy resins modifiedby the polysiloxanes were investigated. It was found that the phase structure and properties of the cured epoxy resins dependmainly on the amino group content in the polydimethylsiloxane and the level of the modifier. The change of phase structure in the cured epoxy resin systems was responsible for the dramatic change in their mechanical and surface properties.
2000, 18(2): 139-148
Abstract:
Some new mesogen-jacketed liquid crystalline polymers (MJLCP) with polymer backbones, spacers, andmesogenic units of different structures were synthesized by radical polymerization. The mesomorphic behavior of thesepolymers was examined using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Theirliquid crystallinity is influenced by the variation of polymer backbone, spacer, mesogenic unit and its terminal groups. Theresults show that...
Some new mesogen-jacketed liquid crystalline polymers (MJLCP) with polymer backbones, spacers, andmesogenic units of different structures were synthesized by radical polymerization. The mesomorphic behavior of thesepolymers was examined using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Theirliquid crystallinity is influenced by the variation of polymer backbone, spacer, mesogenic unit and its terminal groups. Theresults show that...
2000, 18(2): 149-153
Abstract:
"Living"/controlled radical polymerization of ethyl methacrylate (EMA) was carried out with a 2,2'-azobisisobutyronitrile (AIBN)/ferric chloride (FeCl3)/triphenylphosphine (PPh3) initiation system at 85℃. Thc numberaverage molecular weight (Mn) increases linearly with monomer conversion and the rate of polymerization is first order withrespect to monomer concentration. The Mw of PEMA ranges from 3900 to 17600 and the polydispersity indices are quitenarrow (1.09～1.22). The conversion can reach up to ～ 100% and Mw of the polymers obtained is close to that designed.The polymerization mechanism belongs to the reveres atom transfer radical polymerization (ATRP).The polymer was end-functionalized by chlorine atom,which acts as a macroinitiator to proceed extension polymerization in the presence of CuBr/bipy catalyst system via an ATRP process.The presence of ω-chlorine in the PEMA obtained was identified by 1HNMR spectrum.
"Living"/controlled radical polymerization of ethyl methacrylate (EMA) was carried out with a 2,2'-azobisisobutyronitrile (AIBN)/ferric chloride (FeCl3)/triphenylphosphine (PPh3) initiation system at 85℃. Thc numberaverage molecular weight (Mn) increases linearly with monomer conversion and the rate of polymerization is first order withrespect to monomer concentration. The Mw of PEMA ranges from 3900 to 17600 and the polydispersity indices are quitenarrow (1.09～1.22). The conversion can reach up to ～ 100% and Mw of the polymers obtained is close to that designed.The polymerization mechanism belongs to the reveres atom transfer radical polymerization (ATRP).The polymer was end-functionalized by chlorine atom,which acts as a macroinitiator to proceed extension polymerization in the presence of CuBr/bipy catalyst system via an ATRP process.The presence of ω-chlorine in the PEMA obtained was identified by 1HNMR spectrum.
2000, 18(2): 155-160
Abstract:
Polymeric β-cyclodextrin (β-CD) supported by crosslinked poly(acrylamide-co-vinylamine) was synthesized as anartificial analog of hydrolytic enzyme and its catalysis of the hydrolysis of p-nitrophenyl acetate (p-NPA) was theninvestigated. The result showed that the polymer-supported β-CD could accelerate the hydrolytic reaction of p-NPA morequickly than β-CD itself and crosslinked poly(acrylamide-co-vinylamine) alone. The acceleration rate of the polymer-supported β-CD was about 10 times as fast as that of free β-CD in 0.01 mol/L phosphate buffer (pH 7.4) containing 32% DMSO at 37± 0.1 ℃ when the molar amount of β-CD units in the polymer was equal to that of free β-CD in the experiments.The enhanced acceleration of the polymer-supported β-CD should be ascribed to the cooperative contribution of the inclusion effect of β-CD ring and the uncleophilic effect of amino groups on the polymeric support.
Polymeric β-cyclodextrin (β-CD) supported by crosslinked poly(acrylamide-co-vinylamine) was synthesized as anartificial analog of hydrolytic enzyme and its catalysis of the hydrolysis of p-nitrophenyl acetate (p-NPA) was theninvestigated. The result showed that the polymer-supported β-CD could accelerate the hydrolytic reaction of p-NPA morequickly than β-CD itself and crosslinked poly(acrylamide-co-vinylamine) alone. The acceleration rate of the polymer-supported β-CD was about 10 times as fast as that of free β-CD in 0.01 mol/L phosphate buffer (pH 7.4) containing 32% DMSO at 37± 0.1 ℃ when the molar amount of β-CD units in the polymer was equal to that of free β-CD in the experiments.The enhanced acceleration of the polymer-supported β-CD should be ascribed to the cooperative contribution of the inclusion effect of β-CD ring and the uncleophilic effect of amino groups on the polymeric support.
2000, 18(2): 161-168
Abstract:
Silyl celluloses (SiC) were prepared by reacting cellulose with chloropropyltrichlorosilane (CPTCSi) andchloropropyltriethoxysilane (CPTESi) in LiCl/N,N-dimethylacetamide (DMAc). The Si content in the silyl cellulose could becontrolled by adjustment of the molar ratio of silane and cellulose. FT-IR spectra showed that cellulose was readily reactedwith the above two silane reagents, and the reactivity of CPTCSi is higher than that of CPTESi. It was presumed that the reaction process belongs to graft-polymerization.The results of differential thermal analysis (DTA) indicated that the thermostability of the materials produced increased with the increase of Si content in the sample.The acid resistance of the samples SiC in 1 mol/L HCl aqueous solution was improved significantly.When Si content was ca.20%,the silyl cellulose has excellent thermostability,hydrophobicity,low density and stability in 1 mol/L HCl aqueous solution,owing to crosslinking of cellulose chain with silane.
Silyl celluloses (SiC) were prepared by reacting cellulose with chloropropyltrichlorosilane (CPTCSi) andchloropropyltriethoxysilane (CPTESi) in LiCl/N,N-dimethylacetamide (DMAc). The Si content in the silyl cellulose could becontrolled by adjustment of the molar ratio of silane and cellulose. FT-IR spectra showed that cellulose was readily reactedwith the above two silane reagents, and the reactivity of CPTCSi is higher than that of CPTESi. It was presumed that the reaction process belongs to graft-polymerization.The results of differential thermal analysis (DTA) indicated that the thermostability of the materials produced increased with the increase of Si content in the sample.The acid resistance of the samples SiC in 1 mol/L HCl aqueous solution was improved significantly.When Si content was ca.20%,the silyl cellulose has excellent thermostability,hydrophobicity,low density and stability in 1 mol/L HCl aqueous solution,owing to crosslinking of cellulose chain with silane.
2000, 18(2): 169-176
Abstract:
(CpCH2CH2CH = CH2)2MCl2(M=Zr, Hf)/MAO and Cp2ZrCl2/MAO (Cp=cyclopentadienyl; MAO=methylaluminoxane) catalyst systems have been compared for ethylene copolymerization to investigate the influence of theligand and transition metal on the polymerization activity and copolymer properties. For both CH2CH2CH=CH2 substitutedcatalysts the catalytic activity decreased with increasing propene concentration in the feed. The activity of the hafnocenecatalyst was 6～8 times lower than that of the analogous zirconocene catalyst,13C NMR analysis showed that the copolymer obtained using the unsubstituted catalyst Cp2ZrCl2 has greater incorporatiec of propene than those produced by CH2CH2CH=CH2 substituted Zr and Hf catalysts. The melting point, crystallinity and the vicosity-average molecular weight of the copolymer decreased with an increase of propene concentration in the feed. Both CH2CH2CH=CH2 substituted ZR and Hf catalysts exhibit little or no difference in the melting point and crystallinity of produced copolymers.However, there are significant differences between the two zirconocene catalysts. The copolymer produced by Cp2ZrCl catalyst have much lower Tm and Xc than those obtained with the (CpCH2CH2CH=CH2)2ZrCl2 catalyst. The density and molecular weight of the copolymer decreased inthe order: (CpCH2CH2CH=CH2)2HfCl2>(CpCH2CH2CH=CH2)2HfCl2 in ethylene/propene copolymerization and compared the results with those obtained with unsubstituted Cp2ZrCl2 catalyst.
(CpCH2CH2CH = CH2)2MCl2(M=Zr, Hf)/MAO and Cp2ZrCl2/MAO (Cp=cyclopentadienyl; MAO=methylaluminoxane) catalyst systems have been compared for ethylene copolymerization to investigate the influence of theligand and transition metal on the polymerization activity and copolymer properties. For both CH2CH2CH=CH2 substitutedcatalysts the catalytic activity decreased with increasing propene concentration in the feed. The activity of the hafnocenecatalyst was 6～8 times lower than that of the analogous zirconocene catalyst,13C NMR analysis showed that the copolymer obtained using the unsubstituted catalyst Cp2ZrCl2 has greater incorporatiec of propene than those produced by CH2CH2CH=CH2 substituted Zr and Hf catalysts. The melting point, crystallinity and the vicosity-average molecular weight of the copolymer decreased with an increase of propene concentration in the feed. Both CH2CH2CH=CH2 substituted ZR and Hf catalysts exhibit little or no difference in the melting point and crystallinity of produced copolymers.However, there are significant differences between the two zirconocene catalysts. The copolymer produced by Cp2ZrCl catalyst have much lower Tm and Xc than those obtained with the (CpCH2CH2CH=CH2)2ZrCl2 catalyst. The density and molecular weight of the copolymer decreased inthe order: (CpCH2CH2CH=CH2)2HfCl2>(CpCH2CH2CH=CH2)2HfCl2 in ethylene/propene copolymerization and compared the results with those obtained with unsubstituted Cp2ZrCl2 catalyst.
STUDY ON THE CONCENTRATION DEPENDENCE OF ORIENTATION OF POLYSTYRENE ON SILVER BY THE SERS TECHNIQUE*
2000, 18(2): 177-180
Abstract:
Polystyrene films were adsorbed onto a silver surface from dichloromethane solutions with concentrations of 0.1 to12 wt%, and then studied by the surface enhanced Raman technique. A critical concentration for coil interpenetration wasobserved.
Polystyrene films were adsorbed onto a silver surface from dichloromethane solutions with concentrations of 0.1 to12 wt%, and then studied by the surface enhanced Raman technique. A critical concentration for coil interpenetration wasobserved.
