SYNTHESIS AND CHARACTERIZATION OF AMPHIPHILIC GRAFT COPOLYMER CONTAINING MICROPHASE SEPARATED AND LONG POLY(ETHYLENE OXIDE) SIDE CHAIN STRUCTURES**

Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called "selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR, ~1H-NMR and GPC. Various experimental parameters controlling the copolymerization were studied in detail. The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers. A detailed "comb- model" was proposed to describe the molecular structure of the graft copolymers. Finally, this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.     

STUDIES ON THE POLYMERIZATION OF β-CYCLODEXTRIN WITH EPICHLOROHYDRIN*

Different proportions of β-cydodextrin and epichlorohydrin were used to prepare a group of β-cyclodextrin polymers. The relationship between the reaction extent and the molar ratios of reactants was discussed according to the results of ~1H-NMR, ~(13) C-NMR spectra and elemental analysis. Especially, high resolution ~1H-NMR spectra were usd for studying the reaction active sites and the extent of reaction. The solubility of oil soluble drugs in water was largely improved in the presence of water-soluble β-cyclodextrin polymer.     

“LIVING”/CONTROLLED RADICAL POLYMERIZATION OF ETHYL METHYLACRYLATE WITH 2,2’-AZOBISISOBUTYRONITRILE/FERRIC CHLORIDE/TRIPHENYLPHOSPHINE INITIATION SYSTEM

"Living"/controlled radical polymerization of ethyl methacrylate (EMA) was carried out with a 2,2'-azobisisobutyronitrile (AIBN)/ferric chloride (FeCl_3)/triphenylphosphine (PPh_3) initiation system at 85℃. Thc numberaverage molecular weight (M_n) increases linearly with monomer conversion and the rate of polymerization is first order withrespect to monomer concentration. The M_w 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 M_w of the polymers obtained is close to that designed. Thepolymerization mechanism belongs to the reverse 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 ofCuBr/bipy catalyst system via an ATRP process. The presence of ω-chlorine in the PEMA obtained was identified by ~1H-NMR spectrum.     

SYNTHESIS AND CHARACTERIZATI0N OF POLYMETHACRYLATES BEARING HETEROCYCLIC AZO GROUP AND MESOGENIC GROUP FOR NONLINEAR OPTICS

The methacrylate monomers bearing mesogenic group and heterocyclicazo dye have been synthesized. The monomeric dye was copolymerized with the mesogenicmonomer using a free radical initiator to produce polymers useful for nonlinear optics. Themonomers and polymers were characterized by IR, ~1H-NMR, and UV-Vis spectra. Theaverage molecular weight (M_w and M_n) of the polymers were determined by gel permeationchromatography. The thermal properties of the polymers such as thermal stability andphase transition behavior were studied by thermogravimetric analysis, differential thermalanalysis, polarizing optical microscope and X-ray diffractometer. The results demonstratethat the synthesized polymers are crystalline polymers at room temperature and no liquidcrystalline phases were observed for all of them.     

SYNTHESIS OF NOVEL BLOCK COPOLYMERS OF POLY(3-HYDROXYBUTYRIC ACID)WITH POLY(ETHYLENE GLYCOL)THROUGH ANIONIC POLYMERISATION

A novel kind of copolymer with ABA-type block structure was synthesized by anionic ring-openingpolymerization of β-butyrolactone (β-BL) in the presence of a PEG-based dicarboxylates as macroinitiators which wereprepared by the esterification of aliphatic cyclic anhydride and poly(ethylene glycol) (PEG) oligomers (M_n=2000, 4000 and6000) and conversion of potassium dicarboxylates. The resultant copolymers as well as the intermediates were characterizedby IR,~1H-NMR and GPC.     

Preparation of polystyrene/silica nanocomposites by radical copolymerization of styrene with silica macromonomer

A two-stage process has been developed to generate the silica-based macromonomer through surface-modification of silica with polymerizable vinyl groups. The silica surfaces were treated with excess 2,4-toluene diisocynate (TDI), after which the residual isocyanate groups were converted into polymerizable vinyl groups by reaction with hydroxypropylacrylate (HPA). Thus, polystyrene/silica nanocomposites were prepared by conventional radical copolymerization of styrene with silica macromonomer. The main effecting factors, such as ratios of styrene to the macromonomer, together with polymerization time on the copolymerization were studied in detail. FTIR, DSC and TGA were utilized to characterize the nanocomposites. Experimental results revealed that the silica nanoparticles act as cross-linking points in the polystytene/silica nanocomposites, and the glass transition temperatures of the nanocomposites are higher than that of the corresponding pure polystyrene. The glass transition temperatures of nanocomposites increased with the increasing of silica contents, which were further ascertained by DSC.     

EFFECTS OF ω-ACRYLOYL POLY (ETHYLENE OXIDE) MACROMONOMER ON EMULSIFIER-FREE EMULSI0N COPOLYMERIZATION OF METHYL METHACRYLATE AND n-BUTYL ACRYLATE*

Well-defined nonionic hydrophilic ω-acryloyl poly(ethylene oxide) macro-monomer (PEO-A) has been prepared by living anionic polymerization of ethylene oxidewith diphenyl methyl potassium as the initiator and acryloyl chloride as the reaction termi-nating agent. The polymer was characterized by FTIR and SEC. The emulsifier-free emul-sion polymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA) containingvarious concentrations of PEO-A was studied. In all cases stable emulsion coplymerizationsof MMA and BA were obtained. The stabilizing effect was found to be dependent on themolecular weight and the feed amount of the macromonomer.     

SYNTHESIS OF POLY(METHYL METHACRYLATE)-graft-POLYSTYRENE BY ATOM TRANSFER RADICAL POLYMERIZATION

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. Themolecular weight of graft copolymer increased with the monomer conversion, and the polydispersity remained relatively low.The individual grafted polystyrene chains were cleaved from the macroinitiator backbone by hydrolysis and the hydrolyzed product was characterized by ~1H-NMR and GPC.     

Effect of Temperature-responsive Solution Behavior of PNIPAM-bPPEOMA-b-PNIPAM on Its Inclusion Complexation with α-Cyclodextrin

The effect of temperature-responsive solution behavior of PNIPAM-b-PPEOMA-b-PNIPAM on its inclusion complexation with α-cyclodextrin was studied. The triblock polymer was prepared by reversible addition-fragmentation chain transfer(RAFT) polymerization and formed inclusion complexes(ICs) after selective threading of the PEO segment of the triblock polymer through the cavities of α-CD units. For comparison, PPEOMA homopolymer was prepared and the inclusion complexation with α-CD was also studied. The ICs were prepared with α-CD when the polymer was in different conformations by changing the temperature, and the formed ICs were characterized by XRD, 1H-NMR, TGA and DSC. The solutions of the ICs show temperature-responsive clear/turbid transition or fluidic emulsion/gel transition depending on the concentration of the α-CD added, and the stoichiometry determined by 1H-NMR and TGA indicates that the stoichiometry of EO to α-CD of the resulted ICs increases with increasing of temperature.     

SYNTHESIS AND CHARACTERIZATION OF FOUR-ARMED BLOCK POLY(STYRENE-b-p-NITROPHENYL METHACRYLATE)PREPARED BY THE ATRP METHOD*

A novel tetrafunctional initiator, C [CH_2O (CH_2)_3 OOCCH(Br)CH_3]_4 (1), was synthesized through the reaction oftetraol with α-bromopropionyl chloride, and then was used as initiator of atom transfer radical polymerization (ATRP) in thepreparation of 4-armed polystyrene (PSt) with narrow polydispersity. The structure, molecular weight and molecular weightdistribution (MWD) of each arm were studied by ~1H-NMR and GPC data of hydrolyzed products of the 4-armed PSt. TheATRP of St using 1/CuBr/bpy as initiator system is of "living" character based on the following evidence: narrow MWD,constant concentration of chain radical during the polymerization, control of molecular weight by the molar ratio of monomerconsumed to 1. The 4-armed poly(St-b-p-nitrophenyl methacrylate) [poly(St-b-NPMA)] was prepared by the ATRP ofNPMA using 4-armed PSt with terminal bromine as the initiator, and characterized by FT-IR, ~1H-NMR spectra and GPCcurves. The micelles with PSt as core, and PNPMA as shell were formed by dropping DMSO into a solution of 4-armedpoly(St-b-NPMA) in DMF, as proved by laser light scatter (LLS) method.     

PREPARATION AND CHARACTERIZATION OF SOLUBLE SULFONATED POLYBENZIMIDAZOLE FOR PROTON EXCHANGE MEMBRANE MATERIALS

A series of sulfonated polybenzimidazoles(sPBI-SF)were prepared from 2,2-bis(4-carboxyphenyl)hexafluoro- propane(BIS-B-AF),3,3′-disulfonyl-4,4′-dicarboxyldiphenylsulfone(DSDCDPS)and 3,3′-diaminobenzidine(DAB)at various stoichiometric ratio by solution copolycondensation in poly(phosphoric acid).The chemical structure of the resulting sPBI-SF was confirmed by FTIR and ~1H-NMR.The sPBI-SFs with high molecular-weights(M_n=39400-65500)were soluble in DMF,DMSO or DMAc.Therefore,they could form some transparen...     

COPOLYMERIZATION AND DETERMINATION OF MONOMER REACTIVITY RATIOS OF DL-LACTIDE WITH 3-BENZYLOXYMETHYL-1,4-DIOXANE-2,5-DIONE

The copolymerization of DL-LA and 3-BMG was carried out in bulk with Stannous 2-ethylhexanoate as thecatalyst. A series of copolymers with pendant protected groups were obtained and characterized by ~1H-NMR and GPCanalysis. The monomer reactivity ratios were evaluated by the Fineman-Ross method and the Kelen-Tudos method and foundto be r_(BMG) = 1.96 and r_(LA) = 0.37, respectively.     

利用脱镁叶绿酸甲酯的化学修饰合成红紫素酰亚胺衍生物

A series of novel purpurin-18 imide derivatives exhibiting long wavelength absorption and amphiphilicity wereobtained from methyl pheophorbide-a(MPa)by modification of the peripheral functional groups.The vinyl groupat 3-position was oxidized with OsO_4 and NaIO_4 to form the formyl group and the Grignard reaction of this alde-hyde with the alkyl magnesium bromide was carried out to give the corresponding 3-(1-hydroxylalkyl)pheophor-bide-a.The E-ring of these chlorines was converted into anhydride ring to give purpurin derivatives by air oxidation.The trans-3~2-alkyl purpurin derivatives were obtained by dehydration of hydroxyl group at 3~1-position.TheN-hydroxyl purpurin imide was generated by treatment of the anhydride ring with bydroxylamine hydrochloride.The 3~1-alkylacyl-N-hydroxyl purpurin imides were obtained by oxidation of hydroxyl group at 3~1-position.Theacylation of N-hydroxyl group was completed to afford N-acyloxy purpurin imides.The photocytoxicity of severalcompounds in vitro were tested.     

Tailoring the Properties of Diels-Alder Reaction Crosslinked High-performance Thermosets by Different Bismaleimides

A series of Diels-Alder reaction cross-linked thermosets with recyclability and healability were prepared from furan-containing aromatic polyamide and bismaleimides with different chemical structures.The structures of synthesized bismaleimides were confirmed by 1 H nuclear magnetic resonance(1 H-NMR)spectroscopy;their reversible cross-linking with the furanic polyamide was further detected by 1 H-NMR technique and sol-gel transition behavior.The dynamic mechanical analysis and tensile test revealed the variable thermal and mechanical properties of thermosets cross-linked by different bismaleimides and with different molar ratios of maleimide group to furan group(Ima/fur).The tensile test also demonstrated that the better recyclability and solvent-assisted healability of thermosets cross-linked could be achieved by more flexible bismaleimides.This work is expected to provide valuable information for design of recyclable and healable high-performance thermosets with desired properties.     

The amphiphilic multiarm copolymers based on hyperbranched polyester and lysine: Synthesis and self-assembly

The amphiphilic multiarm copolymers were synthesized through the modification of commercially available hyperbranched polyesters(Boltorn H40) with N-ε-carbobenzoxy-L-Lysine N-carboxyanhydride(ZLys-NCA).After being condensed with N-Boc-phenylalanine(Boc-~NPhe) and deprotected the Boc-groups in trifluoroacetic acid(TFA),the original terminal hydroxyl groups were transformed into the amino groups and then initiated the ring-opening polymerization of ZLys-NCA.The hydrophilic poly(L-lysine) was grafted to the surface of Boltorn H40 successfully after the protecting benzyl groups were removed by the HBr solution in glacial acetic acid(33 wt%).The resulting multiarm copolymers were characterized by the ~1H-NMR,GPC and FTIR.The arm length calculated by NMR and GPC analysis was about 3 and 13 lysine-units for H40-Phe-PLysl and H40-Phe-PLys2 respectively.Due to the amphiphilic molecular structure,they displayed ability to self-assemble into spherical micelles in aqueous solution with the average diameter in the range from 70 nm to 250 nm.The CMC of H40-Phe-PLysl and H40-Phe-PLys2 was 0.013 mg/mL and 0.028 mg/mL,respectively, indicating that H40-Phe-PLysl with shorter arm length is easier to self-assemble than H40-Phe-PLys2 with longer arm length.     

Novel Conductive PANI/Hydrophilic Thiacalix[4]areneNanocomposites: Synthesis,Characterization andInvestigation of Properties简

Nanocomposites of polyaniline(PANI) and the macrocycle thiacalix[4]arene tetra sulfonate(TCAS) were successfully synthesized in feed ratios of 1:0.25, 1:0.50 and 1:0.75 by three prevail synthetic methods, i.e. in situ polymerization, emulsion polymerization and solution casting technique. The structures of the nanocomposites were confirmed by FTIR, UV-Vis, XRD, SEM, and TEM techniques. The conductivity was measured by a four probe method. The conductivity was recorded to be as high as 105 × 10 2S cm 1for the nanocomposite with a nanometer size structure and homogeneously distributed morphology. The electroactivity of the nanocomposites was approved by cyclic voltammetry(CV) and impedance spectroscopy technique(EIS). The antioxidant ability and thermal property of the composites were further studied. Preliminary studies have evidenced the production of conductive nanocomposites with good thermal property and relatively good solubility in N-methyl 2-pyrrolidone(NMP), with the antioxidant activity reaching up to 80%.     

Synthesis of graft copolymers with polyisobutylene branch chains

<正>The copolymerization of 4-vinylbenzyl chloride(VBC) and vinyl acetate(VAC) was carried out in toluene at 75℃via radical polymerization using 2,2'-azo-bis-(isobutyronitrile)(AIBN) as an initiator.The random copolymers of poly(4-vinylbenzyl chloride-co-vinyl acetate)(P(VBC-co-VAC)) with number average molecular weight(M_n) from 2000 to 6900,relatively narrow molecular weight distribution(MWD,M_w/M_n ca.2.0) and with different copolymer composition of 4-vinylbenzyl chloride(VBC) from 17 mol%to 62 mol%could be obtained.The P(VBC-co-VAC) copolymers with an average number of 7 to 13 initiating sites of benzyl chloride per macromolecule could be used for the cationic polymerization of isobutylene(IB).The cationic polymerizations of IB were further conducted by using P(VBC-co-VAC) copolymers as macroinitiators in conjunction with TiCl_4 at -40℃in CH_2Cl_2.The effects of VBC/TiCl_4(molar ratio) on monomer conversion,M_n and MWD of the resultant copolymers were investigated under 3 sets of conditions.It is found that P(VBC-co-VAC)-g-PIB copolymers with relatively narrow MWD(M_w/M_n ca.2.0) and with terminal tert-chlorine functional groups in branched PIB chains could be successfully synthesized when VBC/TiCl_4(molar ratio) was set in the range from 0.10 to 1.12.The unimodal GPC curve of the P(VBC-co-VAC)-g-PIB copolymers by RI detector was almost in harmony with the GPC curve by UV detector.The TEM image of the P(VBC-co-VAC)-g-PIB copolymer stained by RuO indicated that the copolymer formed a two-phase morphology with P(VBC-co-VAC)-rich domains of 20-100 nm in size tethered by PIB branch segments.     

PREPARATION OF LOW MOLECULAR WEIGHT POLY（GLYCIDYL METHACRYLATE） BY PHOTOPOLYMERIZATION

Low molecular weight poly（glycidyl methacrylate）s （PGMAs） were prepared by photopolymerization in ethyl acetate, with benzophenone （BP） as photoinitiator, and triethylamine （TEA） as hydrogen donor. The existence of semipinacol dormant end groups in PGMA was confirmed by FT-IR and ^1H-NMR, and the content of the semipinacol dormant groups was determined quantitatively by ^1H-NMR measurement. The effects of various thctors, such as reaction time, BP concentration and monomer concentration on the synthesis of the polymers were investigated systematically. The molecular weights of the polymers were also investigated with GPC. It is shown that increasing BP concentration and decreasing irradiation time and monomer concentration led to a significant decrease of the molecular weights.     

Synthesis,characterization, thermal stability and antibacterial activity of coumarin based methacrylate copolymers

Monomer of 7-methacryloyloxy-4-methylcoumarin(MAOMC) was synthesized and characterized by FTIR, 1H-NMR and 13C-NMR spectroscopy. Copolymers of MAOMC with butoxyethylmethacrylate(BOEMA) at different feed compositions were prepared by free radical solution polymerization at(70 ± 1) °C in ethylmethylketone(EMK) using benzyl peroxide(BPO) as an initiator. The copolymers were characterized by FTIR and 1H-NMR spectroscopy. Thermogravimetric analysis(TGA) and differential scanning calorimetry(DSC) of the copolymers showed moderate thermal stability and higher Tg values. Gel permeation chromatography(GPC) was used to find out the molecular weights of the different copolymers. Antibacterial activities of the copolymers were also investigated against the selected pathogenic bacteria's. The antibacterial activity of the copolymer increases as the MAOMC content increases in the copolymer. This shows that coumarin moiety plays a very important role in the antibacterial activity.     

EFFECT OF TEMPERATURE ON COPOLYMERIZATION PARAMETERS OF HYDROXYETHYL ACRYLATE AND METHYL METHACRYLATE

The copolymerization of 2-hydroxyethyl acrylate (HEA, M_1) and methylmethacrylate (MMA, M_2) in cyclohexanone was studied. The multiple experiments ofsolution copolymerization with low conversion were carried out at two sensitive compositionfeed points at 60, 80, 100, 120 and 140℃, respectively. The composition of the copolymerswas analyzed by ~1H-NMR. The reactivity ratios which were estimated by the Error-in-Variable Method (EVM) of Mayo-Lewis equation were found to be r_1 = 0.328, r_2 = 1.781for 60℃; 0.375, 1.709 for 80℃; 0.406, 1.654 for 100℃; 0.439, 1.540 for 120℃ and 0.455,1.400 for 140℃, and the 95% joint confidence intervals of the reactivity ratios were alsodetermined. According to r_1 and r_2, Arrhenius relations and the activity energy differencebetween the homo- and cross-propagation were calculated.