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.     

Characterization of impact polypropylene copolymers by solvent fractionation

The compositional heterogeneity of two impact polypropylene copolymers(IPCs) was studied by a combinatory investigation of temperature rising elution fractionation(TREF) and solvent fractionation.The chain structures and composition of fractions obtained from solvent fractionation were examined in detail.The TREF results shows that there are much more E-P segmented copolymer and more uniform distribution of ethylene sequence in IPC-1,which is responsible for its better comprehensive mechanical performance.The fractions from hexane and heptane are ethylene-propylene rubber phase and E-P block copolymers respectively.The result of solvent fractionation method also shows that custom hexane or heptane extractions can not extract the E-P copolymer completely.     

Synthesis and characterization of a novel amphiphilic biodegradable β-cyclodextrin/poly(γ-benzyl L-glutamate) copolymer

β-Cyclodextrin/poly(γ-benzyl L-glutamate) (β-CD-PBLG) copolymers were synthesized by ring-opening polymerization of N-carboxy-γ-benzyl L-glutamate anhydride (BLG-NCA) in N,N-dimethylformamide (DMF) initiated by mono-amino-β-cyclodex-trin(H2N-β-CD). The structures of the copolymers were confirmed by IR, 1H NMR and GPC. The fluorescence technique was used to determine the critical micelle concentrations (CMC) of copolymer miceU solution, the diameter and the distribution of micelles were characterized by DLS. The results showed that BLG-NCA could be initiated by H2N-β-CD to produce copolymer. The nano-micells were formed by these copolymers in water.     

PREPARATION AND CELL COMPATIBILITY OF FUNCTIONALIZED BIODEGRADABLE POLY(DL-LACTIDE-co-RS-β-MALIC ACID

In order to create a functionalized biodegradable polymer for vascular tissue engineering application,poly(DL- lactide-co-RS-β-malic acid)(PDLLMAc)was synthesized.PDLLMAc was obtained after hydrogenolysis of poly(DL- lactide-co-RS-β-benzyl malolactonate)(PDLLMA),which was from the ring-opening polymerization of DL-lactide(DLLA) and RS-β-benzyl malolactonate(MA)using stannous octoate as catalyst.The copolymers were characterized by ~1H-NMR, FTIR,GPC and DSC.The tensile strength and water uptake of the copolymers were measured.In copolymerization,the proportion of MA in the derived copolymers was lower than that in the feeding dose,a consequence of its lower reactivity. The molecular weight of the copolymers decreased with increasing MA content.The protective benzyl groups were completely removed in hydrogenolysis.The glass transition temperature(T_g)of the protected copolymers decreased with increasing MA content.The mechanical strength test showed that the tensile strength of PDLLMA decreased while elongation increased with MA content increasing,and the tensile strength increased and elongation decreased with increasing malic acid content in PDLLMAc for the formation of hydrogen bonding.The water uptake showed that more hydrophilic malic acid adsorbed more water in PDLLMAc.In order to test the reactivity of functional pendant groups,bioactive RGD peptide was immobilized on the functionalized polymer film surface and smooth muscle cells(SMCs)were cultured on it. The results showed that the functionalized copolymer was biocompatible and could be potentially applied in vascular tissue engineering.     

Rapid synthesis of biodegradable poly(epsilon-caprolactone-co-p-dioxanone) random copolymers under microwave irradiation

<正>Biodegradable poly(epsilon-caprolactone-co-p-dioxanone)(PCDO) random copolymers have been synthesized by ring-opening polymerization of epsilon-caprolactone(CL) and p-dioxanone(PDO) under microwave irradiation.The effects of irradiation time and different CL/PDO molar feed ratios on the microwave-assisted ring-opening polymerization(MROP) of PCDO have been discussed.The resultant products were characterized by ~1H NMR,GPC and DSC.It was found that the polymerization was completed within 20 min at 140℃.In the presence of different CL/PDO molar feed ratios,the conversions of both monomers were kept relatively constant.DSC sturdy suggested that with increasing the content of PDO in the copolymers,the crystalline degree of the copolymers decreased gradually.It is believed to be a promising biodegradable material.     

Preparation and application of photosensitive copolymers for PDP barrier ribs formed by photolithography

In this work, the photosensitive paste was prepared. It was comprised of inorganic particles and a photosensitive organic component. The inorganic particles included glass, ceramics, and metals. The organic component should contain at least the following photosensitive materials: photosensitive monomers, photoreactive copolymer and photopolymerization initiators. The photoreactive copolymer played a role of an adhesive in the photosensitive paste. Meanwhile in the development stage, the carboxyl groups of the copolymer reacted with the alkalescent developer. Following this, the unexposed part must be removed and an excellent pattern can be formed. A series of three-component acrylic copolymers (MAA/St/MMA) were designed, and then synthesized via free radical polymerization. Subsequently glycidyl methacrylate (GMA) was employed to modify the prepared copolymers through ring-opening reactions between the carboxyl groups and the epoxide groups. Eventually the photosensitive copolymers were obtained and used to form the barrier ribs of PDPs. The chemical structure, glass transition temperature, acid value and molecular weight of photosensitive copolymers had different effects on the structure and pattern of PDP barrier ribs. Through analyzing effects of different polymer performance parameters on the patterns of barrier ribs, the optimal photosensitive copolymer was acquired.     

Graft polymerization of 2-hydroxyethyl methacrylate via ATRP with poly(acrylonitrile-co-p-chloromethyl styrene) as a macroinitiator

Amphiphilic graft copolymers are excellent additives for the development of antifouling membranes by nonsolvent induced phase separation. We report a convenient approach to the synthesis of novel graft copolymers with hydrophobic polyacrylonitrile (PAN) backbones and hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) side chains. Atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate was carried out with poly(acrylonitrile-co-p-chloromethyl styrene) (PAN-co-PCMS) as a macroinitiator in the presence of CuCl/2,2’-bipyridine at 50 °C in dimethyl sulfoxide. Kinetics of the graft polymerization was also evaluated. The synthesis of poly(acrylonitrile-co-p-chloromethyl styrene-g-2-hydroxyethyl methacrylate) (PAN-co-(PCMS-g-PHEMA)) can be relatively controlled when CMS (the ATRP sites) unit in the macroinitiator is around 5 mol%. Both the macroinitiators and graft copolymers were characterized by FTIR, NMR and GPC. The surface morphology and wettability of the copolymer films were studied by AFM and water contact angle measurement, respectively. We demonstrate that phase segregation between the PAN-co-PCMS backbones and the PHEMA side chains takes place and the surface hydrophilicity of the graft copolymers increases with the length of the PHEMA side chains. Because these amphiphilic graft copolymers can be synthesized in mass, they will be useful as latent additives for the fabrication of advanced PAN separation membranes.     

Fabrication of Macroporous Protein-containing Films through the Reverse Emulsions Approach Featuring β-Cyclodextrin-conjugated PEG-PLGA Copolymers

A series of β-cyclodextrin-conjugated 4-arm poly(ethylene glycol)-poly(lactide-co-glycolide)(4-arm PEG-PLGA)copolymers were synthesized by a ring-opening polymerization of D,L-lactide and glycolide using 4-arm PEG as initiator,and then conjugated with mono(6-ethylenediamine-6-deoxy)- β-cyclodextrin(CDen) or ethylenediamino-bridged bis- β-CD(BCDen). The chemical structures of copolymers were confirmed by ~1H-NMR and FTIR spectroscopy. The β-CD-conjugated PEG-PLGA formed stable reverse micelles due to the formation of β-CD and bovine serum albumin(BSA) inclusion complexation, which could accommodate BSA in the organic solvent with improved encapsulation efficiency. Moreover, we demonstrated a one-step approach to construct macroporous protein-containing films using these reverse micelles. The films with ordered pore arrays were directly prepared from reverse micelles. Interestingly, the protein was totally located in the whole matrix except for the pores.     

Synthesis and characterization of in-chain silyl-hydride functional SBR and self-crosslinking elastomer

Functional in-chain silyl-hydride(Si-H) SBR copolymers of 4-vinyiphenyldimethylsilanol(VPDMS) and butadiene were synthesized by living anionic polymerization,in which active group Si-H was not lost and its content was controllable. Corresponding self-crosslinking elastomers were obtained by hydrosilation of Si-H group with vinyl bonds in chain.The copolymers and elastomers were characterized by ~1H NMR,size exclusion chromatography(SEC),Fourier transform infrared (FTIR) spectroscopy,differential scanning calorimetry(DSC),and thermogravimetry analysis(TGA) techniques.     

Synthesis and characterization of Fe(II)-coordinated PS-b-P[NIPAM-co-(VBC-Fe-DMAP)] block copolymers

In this work,a new type of block polymers,polystyrene-b-poly[(N-isopropyl acrylamide)-co-(vinyl benzyl chloride)](PS-b-P(NIPAM-co-VBC)),was prepared via reversible addition fragmentation transfer polymerization,then pentacyano(4-(dimethylamino pyridine))ferrate(Fe-DMAP) was attached to VBC units through a quaternization process.The Fe(Ⅱ)-coordinated PS-b-P[NIPAM-co-(VBC-Fe-DMAP)]block copolymers were characterized by ~1H-NMR,FT-IR and TGA.The self-assembly behavior of the block copolymers was also investigated and the micelle morphology was characterized by TEM.It was found that the PS-b-P(NIPAM-co-VBC) block polymer and Fe-coordinated block copolymer could both form spherical micelles in DMF/MeOH mixed solvent.     

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.     

SYNTHESIS AND CHARACTERIZATION OF POLY(AMINO ACID-UREA)S COMPRISING NOVEL TRIBLOCK COPOLYMERS OF POLY(TETRAHYDROFURAN) AND POLY(γ-BENZYL L-GLUTAMATE)S

A kind of novel triblock copolymers of poly(γ-benzyl L-glutamate)-b-poly(tetrahydrofuran)-b-poly(γ-benzyl L-glutamate)s(PBLG-b-PTHF-b-PBLG)was synthesized by using bis(3-aminopropyl)terminated polytetrahydrofuran to initiate the ring-opening polymerization ofγ-benzyl L-glutamate N-carboxyanhydride(BLG-NCA).The corresponding multiblock poly(amino acid-urea)s were prepared in one-pot protocol from the chain extension of PBLG-b-PTHF-b-PBLG with MDI.The resulting triblock and multiblock copolymers were chara...     

THE EFFECT OF MONOMERS FEEDING METHODS ON EMULSION COPOLYMERIZATION OF VINYLIDENE CHLORIDE AND ACRYLATES

The emulsion copolymerization of vinylidene chloride (VDC) with methyl-methacrylate(MMA) and acrylonitrile (AN) was carried out by batch, seeded batch and semicontinuous pro-cesses,respectively. Significant differences were found in the physical and mechanical propertiesof the latexes and films, depending on the methods of monomer feeding. The results both intheory and experiments demonstrated that the copolymer composition and the length of the VDC sequences in the copolymer could be controlled by the modes of monomer feeding process.     

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.     

Curing Kinetics and Thermal Stability of Diglycidyl Ether of Bisphenol‐A Using Mixtures of Heterocyclic Derivatives of Stannanes and 4,4′‐Diaminodiphenylsulfone

Curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) in the presence of varying molar ratios of derivatives of stannanes to 4,4'-diaminodiphenylsulfone (DDS) was investigated by the dynamic differential scanning calorimetry. The derivatives were synthesized by reacting 1 mole of biguanide (B) with 1 mole of phenylethyltindihydride (PETH) or phenylmethyltindihydride (PMTH) or phenylbutyltindihydride (PBTH) and designated as BPETH or BPMTH or BPBTH respectively. These derivatives were characterized by elemental analysis and spectroscopic techniques such as IR, ¹H NMR, ¹³C NMR and ¹¹⁹Sn NMR. The mixtures of these derivatives to DDS at ratios of 0∶1, 0.25∶0.75, 0.5∶0.5, 0.75∶0.25 and 1∶0 were used to investigate the curing behaviour of DGEBA. The multiple heating rate method (5, 10, and 15 and 20 ℃•min^－1) was used to study the curing kinetics of epoxy resins. The thermal stability of the isothermally cured resins was also evaluated using dynamic thermogravimetry in a nitrogen atmosphere.     

Synthesis and Characterization of ABBA Block Copolymer of Glycolide and ε-Caprolactone

A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ε-Scaprolactone (CL, B) and glycolide (A) by means of step polymerization in the presence of ethylene glycol as an initiator and stannous octanoate as a catalyst at 110 ℃ for 48 h. The molecular length of the PCL prepolymer(BB) could be adjusted by controlling the molar ratio of the ethylene glycol initiator to ε-caprolactone monomer. The structure and the composition of the block copolymer were determined by the weight ratio of the monomer glycolide (A) to PCL pre-polymer(BB). The block copolymers were characterized by ^1H NMR, GPC, DSC and X-ray. The results confirm the successful synthesis of an ABBA block copolymer.     

Synthesis and characterization of copolymers based on benzothiadizole-thiophene-phenylenevinylene

<正>Two novel copolymers based on benzothiadizole-thiophene-phenylenevinylene have been synthesized through palladium catalyzed triple-bond polycondensation method.The copolymers exhibit good solubility in common organic solvents such as CHCl_3,CH_2Cl_2 and THF.The structures and properties of the two copolymers are characterized by FT-IR, ~1H-NMR,UV-Vis absorbance(Abs),gel permeation chromatography(GPC),thermal gravimetric analysis and cyclic voltammetry(CV).The copolymers of P_1 and P_2 show absorption spectra with maximum peak at 532 nm and 573 nm in solution,respectively.Compare to their monomers M_1 and M_2,the absorption peaks of P_1 and P_2 were red-shifted by 34 nm and 54 nm respectively.Thermal gravimetric analysis demonstrated that the polymers were stable and little weight loss was observed below 300℃.Cyclic voltammetry experiments showed that the band gaps of the copolymers were 1.81 eV and 1.62 eV,respectively,suggesting their potential for applications as organic solar cell materials.     

生物相容性BAB型两亲嵌段共聚物的合成及其自组装

Lys(z)-NCA was synthesized in the presence of triphosgene, amphiphilic triblock copolymers poly(N^c-CBZ-Lysine)-PEG-poly(N^c-CBZ-Lysine) were synthesized in DMF using amino-end ended PEG as initiator with the mechanism of anion ring opening polymerization. The structures of block copolymers were characterized by IR, ^1H-NMR,GPC and DSC. The results showed triblock copolymers with expected structure and low polydispersity in molecular weight could be synthesized by this method. At the same time, the self-assembling behaviors of block copolymer were investigated by TEM. A novel helical aggregates were found to be formed in DMF. Because of biocompatibility of two components of block copolymers, these block copolymers have potential applications in the field of biomaterials.     

Metal-free synthesis of amphiphilic functional polycarbonates

Amphiphilic block copolymers of poly(5-benzyloxy trimethylene carbonate)(PBTMC) and poly(ethylene glycol)(PEG) were synthesized through enzymatic polymerization using immobilized porcine pancreas lipase(IPPL).The obtained copolymers with different compositions were characterized by GPC and ~1H NMR.The copolymer composition was in agreement with the feed ratio. The molecular weight of the copolymers showed an increasing trend with the decrease of PEG contents.Micelles of the copolymers were formed by dialysis procedure,and characterized by transmission electron microscopy (TEM).     

MONOMER REACTIVITY RATIO AND THERMAL PERFORMANCE OFα-METHYL STYRENE AND GLYCIDYL METHACRYLATE COPOLYMERS

<正>Synthesis and characterization of the copolymers(PAG) ofα-methyl styrene(AMS) and glycidyl methacrylate (GMA) are presented.The copolymers of PAG were characterized by gel permeation chromatography(GPC),Fourier transform infrared spectroscopy(FTIR),nuclear magnetic resonance(~1H-NMR) and thermogravimetery(TG).Based on the copolymer compositions determined by ~1H-NMR,the reactivity ratios of AMS and GMA were found to be 0.105±0.012 and 0.883±0.046 respectively by Kelen-Tüds method.TG revealed that thermal stability of the copolymers decreased with increasing the AMS content in the copolymers,which indicated that the degradation was mainly caused by the chain scission of AMS-containing structures.Under heating,the copolymers depolymerize at their weak bonds and form chain radicals, which could further initiate other chemical reactions.