SYNTHESIS AND CHARACTERIZATION OF GRAFT COPOLYMERS BASED ON POLY(p-PHENYLENE TEREPHTHALAMIDE) BACKBONE AND WELL-DEFINED POLYSTYRENE SIDE CHAINS

A novel dualfunctional monomer, 2-（2＇,2＇,6＇,6＇-tetramethyl-piperidinyl-1＇-oxy）methylbenzene-1,4-dioyl chloride hydrochloride, with two acid chloride groups for step-growth polymerization and a nitroxide group for the mediation of living radical polymerization was synthesized. It was first copolymerized with terephthaloyl chloride and p- phenylenediamine at a feed molar ratio of 1：3：4 in N-methyl-2-pyrrolidone containing 10 wt% calcium chloride at -10℃ to yield a poly（p-phenylene terephthalamide） based macroinitiator, which initiated radical polymerization of styrene at 125℃ to obtain a series of poly（p-phenylene terephthalamide）-g-polystyrenes. A combinatory analysis of proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, elementary analysis, thermogravimetry and gel permeation chromatography indicated that the macroinitiator induced the radical polymerization of styrene to proceed in a well- controlled way. The molecular weight of side-chains increased with an increase of monomer conversion, and the molecular weight distribution index remained lower than 1.5. The graft copolymers showed a remarkably improved solubility in N- methyl-2-pyrrolidone and much depressed crystallinity in bulk.

CHARACTERIZATION OF AMPHIPHILIC AND MICROPHASE SEPARATED GRAFT COPOLYMERS Ⅱ SURFACE CHARACTERIZATION AND IN VITRO BLOOD-COMPATIBILITY ASSESSMENT OF POLYSTYRENE-GRAFT-ω-STEARYLPOLY (ETHYLENE OXIDE)

This paper reported the research results concerning the surface characterization ofpolystyrene-graft-w-stearyl poly(ethylene oxide) (PS-g-SPEO) by means of XPS,contactangle measurement and TEM, and its in vitro blood compatibility assessment by measuringthe plasma recalcification time (RT) and partial thromboplastin time (PTT). The XPSresults demonstrated that the surface and bulk composition of the PS-g-SPEO graftcopolymers differ remarkably from each other,and that SPEO component was constantlyenriched at the copolymer/air interface. Contact angle studies indicated that the surfacewater wettability can be adjusted effectively by changing the composition of the copolymer.PS-g-SPEO graft copolymers can undergo microphase separation as clearly illustrated byTEM photographs. The relationship between the surface properties of PS-g-SPEO graftcopolymer and its blood compatibility was also discussed.

Formation of polymer vesicles by amphiphilic fluorosiloxane graft copolymers in solution

Amphiphilic fluorosiloxane graft copolymers with a poly（dimethylsiloxane） （PDMS） backbone, a hydrophobic fluorosiloxane side-chain and three hydrophilic polyether side-chains were synthesized by hydrosilation reaction in this work. The micellization of amphiphilic graft copolymers in the water/ethanol solvent system was investigated, and vesicles with different size were formed after the self-assembly system was aged for different time.

Block and Hetero Ethyl Cellulose Graft Copolymers Synthe- sized via Sequent and One-pot ATRP and ＂Click＂ Reactions

Ethyl cellulose graft copolymers with block and hetero side chains, ethyl cellulose graft [polystyrene-b-poly- （ethylene glycol）] [EC-g-（PS-b-PEG）] and ethyl cellulose graft polystyrene and polyethylene glycol [EC-g-（PS-PEG ）] were synthesized by atomic transfer radical polymerization （ATRP） and alkyne-azide ＂click＂ reactions and ＂one-pot＂ ATRP and ＂click＂ reactions, respectively. For the synthesis of EC-g-（PS-b-PEG）, the macroinitiator for ATRP was first synthesized via the esterification of hydroxyl groups of EC with 2-bromoisobutyryl bromide to re- sult ethyl cellulose 2-bromoisobutyryl ester （EC-Br）. The degree of substitution of bromide groups, which deter- mined the graft density, can be tailored by varying the feeding ratios of the hydroxyl groups to 2-bromoisobutyryl bromide. Then ATRP was carried out for preparing EC-g-PS-Br with well-defined length of PS chains. The EC-g-PS-Br copolymers were then converted to EC-g-PS-N3 and then reacted with end alkyne-functionalized PEG via click to result in EC-g-（PS-b-PEG）. The EC-g-（PS-PEG） copolymers were synthesized by converting bromide groups of EC-Br to azide groups （EC-Br-N3） and then by one-pot ATRP and ＂click＂ reactions. The resultant graft copolymers were characterized by FTIR and IH NMR. The results indicate the success of the synthetic procedure of the cellulose grail copolymers with block and hetero side chains.

Performance and synergistic effect of phenolic and thio antioxidants in ABS graft copolymers

The synergistic effect of phenolic and thio antioxidants on the stabilization of acrylonitrile-butadienestyrene(ABS)graft copolymers has been studied.Three commercial antioxidants Irganox245,Irganox1076 and dilauryl thiodipropionate(DLTP)were selected.Formulations based on hindered phenols and secondary antioxidant DLTP were prepared.Stabilization was monitored in terms of changes in the functional groups(oxidation products),tensile properties and yellowness index.Differential scanning calorimetry(DSC)and thermogravimetry(TG)were also used to assess the stability.The results indicated that the combination of Irganox245 and DLTP showed much better stabilization effect than the individual components due to the strong synergistic effect.Only weak synergism could be observed in the formulation that contained Irganox1076 and DLTP.Irganox1076 and Irgnox1076/DLTP exhibited similar behaviors between antioxidants with the highest and lowest efficiencies.

Antibacterial Behaviour of Quaternized Poly(vinyl chloride)-g-Poly(4-vinyl pyridine) Graft Copolymers

Amphiphilic graft copolymers consisting of poly（vinyl chloride）（PVC） main chains and poly（4-vinyl pyridine）（P4VP） side chains were synthesized via atom transfer radical polymerization（ATRP） using direct initiation of chlorine atoms. The successful synthesis of PVC-g-P4 VP graft copolymers was confirmed by Fourier transform infrared spectroscopy（FTIR） and proton nuclear magnetic resonance（1H-NMR）. Transmission electron microscope（TEM） and small angle X-ray scattering（SAXS） analysis showed that PVC-g-P4 VP exhibited microphase-separated, ordered structure with 37.6 nm of domain spacing, which was not observed in neat PVC. For antibacterial applications, the tertiary nitrogen atoms of PVC-gP4 VP was quaternized using 1-bromohexane, as confirmed by FTIR measurements. Bacteria including Escherichia coli（E. coli）, Staphylococcus aureus（S. aureus）, Bacillus cereus（B. cereus）, and Pseudomonas aeruginosa（P. aeruginosa） were completely killed in 24 h on the quaternized PVC-g-P4VP（46% grafting） surface, indicating its excellent antibacterial behavior while it showed to be cytotoxic to mammalian cell.

Biocompatible,Hemocompatible and Antibacterial Acylated Dextran-g-polyisobutylene Graft Copolymers with Silver Nanoparticles

The novel amphiphilic acylated dextran-g-polyisobutylene(AcyDex-g-PIB)graft copolymers with different branch lengths(A4nPtB,2600-5800 g/mol)and grafti ng numbers(GN,5-28 per 1000 Dex mono saccharide)were successfully synthesized via the nu cleophilic substitution of the hydroxyl(-OH)side groups along AcyDex backb one by the living PIB-THF4+chai ns prepared through cati onic polymerizatio n.The crystallizati on of AcyDex backb one in AcyDex-g-PIB graft copolymers was con fined due to the prese nee of PIB branches and the morphology changed from short rod-like crystals to fragment-like crystals with increasing Mn P|B and GN.The obvious microphase separation occurred due to the incompatibility between hard AcyDex backbone and soft PIB branches.AcyDex-g-PIB graft copolymers exhibit excellent biocompatibility towards HeLa cells and good hemocompatibility with red blood cells(RBCs),both of which increase with increasing GN.The in creases of water con tact angle and roughness on the surface of the graft copolymers with in creasi ng A4nP|B and GN manifest the anti-protein adsorption performance.The amphiphilic AcyDex-g-PIB graft copolymers could self-assemble in aqueous solution into nanospheres,which can be used as pH-sensitive drug carriers and can release 100%of the loaded drug within 72 h at pH=7.4.AcyDex-g-PIB graft copolymers bearing silver nanoparticles(Ag-NPs,0.8 wt%-3.9 wt%,4.5-9.5 nm)show good antibacterial properties.This kind of amphiphilic graft copolymer would have a promising prospect in biological and medical fields.

Effects of Branches on the Crystallization Kinetics of Polypropylene-gPolystyrene and Polypropylene-g-Poly(n-butyl acrylate) Graft Copolymers with Well-defined Molecular Structures

Effects of branches on the crystallization kinetics of polypropylene-g-polystyrene （PP-g-PS） and polypropylene-g- poly（n-butyl acrylate） （PP-g-PnBA） graft copolymers with well-defined molecular structures were systematically investigated by DSC. The Avrami equation was used to analyze the isothermal crystallization process, while the analysis of nonisothermal crystallization process was based on the Jeziorny-modified Avrami model and Mo model. The kinetics results of isothermal and nonisothermal crystallization verified the peculiar effects of branches on the crystallization process of PP backbones in PP-g-PS and PP-g-PnBA graft copolymers： on one hand, the interaction between branches （n-n interaction between PS branches, or dipole-dipole interaction between PnBA branches） restrained the mobility and reptation ability of the PP backbones, which hindered the crystallization process; on the other hand, the heterogeneous nucleation effect resulting from the branched structure and fluctuation-assisted nucleation mechanism （caused by microphase separation between the PS or PnBA rich phase and the PP rich phase） became more pronounced with increasing branch length, which facilitated the crystallization process.

Amphiphilic Graft Copolymers of Hydroxypropyl Cellulose Backbone with Nonpolar Polyisobutylene Branches

The novel amphiphilic graft copolymers with hydrophilic hard polar hydroxypropyl cellulose(HPC)backbone and hydrophobic soft nonpolar polyisobutylene(PIB)branches have been successfully synthesized through nucleophilic substitution reaction of living PIB chains carrying oxonium ions with the-OH groups along HPC backbone.The PIB branch length in the graft copolymers could be designed by living cationic polymerization and the grafting density could be adjusted by PIB+/-OH molar ratio.The living PIB chains carrying oxonium ion were prepared by transformation of allyl bromide end groups in the presence of AgCI0_(4) and silver nanoparticles(3.2±0.3 nm,0.7 wt%-1.8 wt%)generated in situ from AgBr.The phase-separation morphology was formed in the graft copolymers due to their incompatibility between backbone and branches.The hydrophilicity on the surface of graft copolymer films could be turned to hydrophobicity by increasing grafting density or/and length of PIB branches.The soft PIB segments in graft copolymers provided an unique surface wa self-assembly for ant卜protein adsorption against bovine serum albumin.A small amount of Ag nanoparticles in the copolymers contributed to good antibacterial activities against Staphylococcus aureus or Escherichia coli.

Self-assembly of block copolymers grafted onto a flat substrate:Recent progress in theory and simulations

Block copolymers are a class of soft matter that self-assemble to form ordered morphologies on the scale of nanome- ters, making them ideal materials for various applications. These applications directly depend on the shape and size of the self-assembled morphologies, and hence, a high degree of control over the self-assembly is desired. Grafting block copolymer chains onto a substrate to form copolymer brushes is a versatile method to fabricate functional surfaces. Such surfaces demonstrate a response to their environment, i.e., they change their surface topography in response to different external conditions. Furthermore, such surfaces may possess nanoscale patterns, which are important for some applica- tions; however, such patterns may not form with spun-cast films under the same condition. In this review, we summarize the recent progress of the self-assembly of block copolymers grafted onto a flat substrate. We mainly concentrate on the self-assembled morphologies of end-grafted AB dibloek eopolymers, junction p0int-grafted AB diblock copolymers （i.e., Y-shaped brushes）, and end-grafted ABA triblock copolymers. Special emphasis is placed on theoretical and simulation progress.

STUDY ON DYNAMIC MECHANICAL BEHAVIOUR OF POLY BUTYLACRYLATE GRAFT VINYL CHLORIDE COPOLYMERS

Dynamic mechanical behaviours of PVC ho-mopolymer. poly butylacryiate (PBA ) graft vinylchloride copolymers and blend of PVC and ACR have been investigated. The results reveal that there is semicompatible nature in the two phases in these materials,that the compatibility of the two phases decrease, -with the increase of crosslinking density of PBA backbone in graft copolyers. For different copolymer types-PB A graft copolymers had better compatibility of the two phases compared ivith the graft copolymers 晈ith core/shell backbone poly-

MOLECULAR DESIGN SYNTHESIS AND PROPERTIES OF SIX KINDS OF MULTIPHASE (STYRENE-ETHYLENE OXIDE)COPOLYMERS

Multiphase copolymers of styrene (S) and ethylene oxide (EO) are amphiphilic, because of the hydrophobic and amorphous polystyrene (PS) segments and the hydrophilic and crystalline polyoxyethylene (PEO). They have many uses including polymeric surfactants, electrostatic charge reducers, compatibilizer in polymer

Design and comparative in-vitro and in-vivo evaluation of starch-acrylate graft copolymer based salbutamol sulphate sustained release tablets

The present work deals with the development of controlled release tablets of salbutamol sulphate(SS)using graft copolymers of methyl methacrylate(St-g-PMMA and Ast-g-PMMA)on starch and acetylated starch.Formulations were evaluated for physical characteristics like hardness,friability,drug release,drug content and weight variations,which fulfilled all the official requirements of tablet dosage form.The release rates from formulated matrix tablets were studied at SGF(pH 1.2)followed by SIF(pH 6.8).Drug release from the graft copolymer based tablets was found to be sustained upto the 14 h with>75%drug release.The in-vitro release study showed that the graft copolymer based matrix formulations(F3&F4)exhibited highest correlation value(r2)for higuchi kinetic model and Korsmeyer's model with n values between 0.61 and 0.67 proved that release mechanisms were governed by both diffusion and erosion mechanism.There was no significant difference in the pharmacokinetic parameters(tmax,Cmax,AUC,Ke,and t1/2)of the graft copolymers matrices and HPMC K100M matrix tablets,indicating their comparable sustained release effect.The potential of graft copolymers to sustain the drug release is well supported by in-vivo pharmacokinetic studies and their adequate physicochemical properties make them promising excipients for controlled drug delivery system.

Phase Transition and Micellization of Temperature Responsive Dextran-graft-poly (N-isopropylacrylamide) Polymers

Phase behavior and micellization of dextran-graft-poly (N-isopropylacrylamide) (PNIPAAm) polymers in aqueous solution are investigated in this paper using DSC and AFM methods. It is found that with the increase of grafting (G%) of the copolymers the endothermic enthalpy during the phase transition increases significantly and the transition temperature decreases slightly. The phase transition behavior of the copolymers is scanning rate dependent. Micelles are formed whenever the solution temperature is raised above the LCST of the copolymers. It is proposed that by using this thermal responsive property of the copolymers, drugs could be incorporated into the micelles without employing any organic solvent.

SYNTHESIS OF A COMB GRAFT COPOLYMER VIA RING OPENING METATHESIS POLYMERIZATION CATALYZED BY SUPPORTED RHUTHENIUM CARBENE COMPLEX

Chloromethyl-2-norbornene was synthesized via Diels-Alder reaction of cyclopentadiene and allyl chloride using a polymer supported boron trifluoride as the catalyst, and was then lithiated and used to initiate a living anionic polymerization of styrene to prepare a macromonome, 5-polystyryl-2-norbornene NBPS. Comb graft copolymer PNBgPS was synthesized via ring opening metathesis polymerization of the macromonomer under the catalysis of ruthenium carbene complex RuCl2(PPh3)2(=CCHtBu) and its polymer supported correspondent. Experimental results showed that the behavior of both the supported boron and supported ruthenium catalysts are superior to their unsupported counterparts. The possible promotion mechanism of the tailor-made supports is discussed.

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.

Study on PVC Grafted with Acrylic Rare Earths

The copolymers were formed by the graft copolymerization of PVC with acrylic rare earth. The principle and method of the graft copolymerization of PVC and acrylic rare earth were discussed. The graft copolymers were characterized by FT-IR spectra and scanning electron microscope (SEM).The thermal stability of the graft-copolymers was studied by thermogravimetric analysis (TG). The experiment results show that the thermal resistance and toughness of the graft copolymers are obviously enhanced.

Determination of Crosslinking and Grafting in Polyurethane-acrylic Hybrid Material and Their Theoretical Calculations

A theoretical method to calculate the mode of polyurethane（PU） prepolymers grafted to polyacrylic（PAC） was presented. Using hydroxyethyl acrylate（HEA） as coupling agent, polyurethane-acrylics（PU-AC） hybrid latexes were prepared with varying HEA level and the reaction of HEA with PU prepolymers at different temperatures, and PU grafted to PAC was experimentally determined. The results show that PU grafted to PAC regularly increased, and the non-grafted and linear free PU regularly decreased with increase in HEA/NCO（isocyanate group）. The grafted PU on PAC was not proportional to HEA. More than half of linear PU prepolymers were grafted to PAC when HEA was at a low level with HEA/NCO at 0.33. While grafted PU increased to 84.80%（mass fraction）, when HEA/NCO increased to 1.0. The results were interpreted based on the theoretical calculation of PU grafted to PAC by the present method.

Chitosan-graft-poly(L-glutamic acid) Hybrid Material and Its Self-assembly

Chitosan-graft-poly（L-glutamic acid）（CS-g-PGA） copolymer was successfully synthesized by grafting polymerization of γ-benzyl-L-glutamate N-carboxyanhydride onto the modified chitosan chains. The self-assembly behavior of such a CS-g-PGA amphiphilic copolymer was studied. The results show that spherical nanoparticles have been formed. The size of CS-g-PGA nanoparticles is found to be controlled by the grafting ratio of PGA. These bio-based polysaccharide/polypeptide hybrid nanoparticles with controllable size may have great potential application in biomedical fields, such as drug delivery systems.

Synthesis and characterization of biodegradable amphiphilic PEG-grafted poly(DTC-co-CL)

A novel biodegradable copolymer, poly（5,5-dibromomethyltrimethylene carbonate-co-ε-caprolactone） （poly（DBTC-co-CL）） with pendant bromine groups, was synthesized via ring-opening polymerization （ROP） of ε-caprolactone （CL） and 5,5- dibromomethyltrimethylene carbonate （DBTC） using stannous octoate （Sn（Oct）2） as catalyst. Then the pendant bromine groups were completely converted into azide form, which permitted ＂click＂ reaction with alkyne-terminated polyethylene （A-PEG） by Huisgen 1,3-dipolar cycloadditions preparing biodegradable amphiphilic poly（DTC-co-CL）-g-PEG graft copolymer. The graft copolymer was characterized by nuclear magnetic resonance （NMR） and size-exclusion chromatography （SEC）.