SYNTHESIS OF OLIGO(OXYETHYLENE) MACROMONOMER CARRYING SULFONATE

This letter reports the synthesis of macromonomers, in which oligo(oxyethylene) chain and sodium salfonate are contained together. This kind of macromonomers has potential application in the fabrication of functional polymers, especially in the study of single-ionic conductors. Some preliminary characterizations of the monomer by IR, IH-NMR, etc. are given as well.

Graft Polymerization of Acryloyloxystarch with Poly (D, L-lactide) Macromonomer——A Potential Drug Delivery Carrier for Oral Administration

Starch is the second largest natural biopolymer. Its unique biodegradable and biocompatible properties make it be increasingly applied to the field of biomedicine. As one kind of polysaccharide, starch is easily degraded into small organic molecules by amylase in the alimentary canal. The fact that the activity of amylase is restrained in the high acid environment in stomach provides an opportunity to prepare an intestinal-specific delivery carrier with

SYNTHESIS AND POLYMERIZATION OF α-METHACRYLYOXYLETHYLOXYCARBONYLMETHYL-ω-(N,N-DIETHYLDITHIOCARBAMYL)POLYSTYRENE MACROMONOMERS

Polystyrene macromonomers with different molecular weight were prepared by radical polymerization of styrene(St) in benzene using β-methacryloxylethyl 2-N,N-diethyldithiocarbamylacetate (MAEDCA) as a monomer-iniferter.Characterization of the macromonomer by ~1H-NMR showed that the end groups were α-methacrylyoxylethyloxycarbonyl-methyl and ω-(N,N-diethyldithiocarbamyl). The macromonomer was difficult to homopolymerize, but it was easilycopolymerized with methyl methacrylate (MMA) initiated by AIBN to form graft copolymers (PMMA-g-PSt) with PStbranches randomly distributed along the PMMA backbone. Copolymerization reaction and the structure of the graft copolymers were strongly affected by M_n and concentration of the macromonomer. The composition and M_n of the purified graft copolymer were determined by ~1H-NMR and GPC analysis.

Synthesis of Dendronized Aromatic Polyamides with Chloromethyl Groups in the Periphery by Macromonomer Approach

The preliminary results for one-pot synthesis of dendronized aromatic polyamides with chloromethyl groups in the periphery by approach were reported first time. The GPC analysis of the resulting dendronized polymers has shown typical weight average molecular weight （Mw） of 41554 and a polydispersity of 2.74.

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.

Preparation of stable micropatterns of gold on cell-adhesion-resistant hydrogels assisted by a hetero-bifunctional macromonomer linker

Surface patterning is very useful in biomaterial studies, yet it is not easy to prepare a micropattern with cell-adhesion contrast that is stable in a wet environment. Recently, a platform technique of transfer photolithography was invented to fabricate stable metal microarrays on the surface of a cell-adhesion resistant and mechanically biomimetic poly（ethylene glycol） hydrogel; the linker is the key chemical in such a transfer strategy. This article reports the design and synthesis of a hetero-bifunctional macromonomer linker with a thiol group at one end and an acryloyl group at the other end. The bifunctional linker was char- acterized by GPC and ~H NMR, and the average number of thiol groups in the bifunctional linker was detected by Ellman＇s reagent. The regent stability under wet conditions was also confirmed by the model reactants. The resultant micropatterned surfaces are meaningful for future studies of cell behaviors on mechanically biomimetic matrixes.

Ceiling Degree of Polymerization for Brush Polymers Prepared via ROMP of Poly（tert-Butyl Acrylate） Macromonomers

Controlled preparation of brush polymers is important in the design of functional materials. In this study, poly（tert-butyl acrylate） macromonomers functionalized with norbornenyl end group（NB-PtBA） were synthesized via atom transfer radical polymerization in three different molecular weights, 2000（NB-PtBA-2k）, 3000（NB-PtBA-3k）, and 8000（NB-PtBA-8k）. Additionally, brush polymers with PtBA as side chains were synthesized via ring-opening metathesis polymerization（ROMP）. Kinetic studies on ROMP of NB-PtBA showed that there was a ceiling degree of polymerization（CDP） for the brush polymers, beyond which the polymerization of NB-PtBA was out of control. For brush polymers of P[NB-PtBA-2k] and P[NB-PtBA-3k], CDPs were estimated to be ca. 400, but the value of P[NB-PtBA-8k] was ca. 100. Therefore, the controlled ROMP of brush polymers was critical at the CDP limit with increased macromonomer molecular weight.

Effects of Ethylene Oxide Spacer Length on Solution Properties of Water-Soluble Fluorocarbon-Containing Hydrophobically Associating Poly(Acrylic Acid-co-R_f-PEG Macromonomer)

Poly(acrylic acid)s (PAAs) modified with a series of fluorocarbon group (R f) end capped Poly(ethylene glycol) (PEG) macromonomers (number of ethylene oxide unit: 1, 9, 23, 45) and corresponding copolymers without fluorocarbon end groups were synthesized. It was found that the effect of the hydrophobic association of fluorocarbon groups on the solution viscosity prevailed over that of the hydrogen bond between grafted PEG and the backbone. Rheological measurement on the aqueous solutions of these poly(acrylic acid co R f PEG macromonomer)s demonstrated that the best thickening performance was shown when the number of ethylene oxide unit (EO number) was 23.

Preparation and Characterization of Polymeric Microspheres Having Isotactic Poly(methacrylic acid) on Their Surfaces

A poly（ tert -butyl methacrylate）（PBMA） macromonomer was synthesized by anionic polymerization with bis（2,6-di- t -butyl phenoxy） methyl aluminum [MeAl（ODBP）2] as the initiator and trimethylsilylmethacrylate（TMSMA） as the end capping agent in dry THF. Then, a poly（methacrylic acid）（PMAA） macromonomer was obtained by means of hydrolysis reaction from the PBMA macromonomer in the presence of hydrochloric acid. The structures of the PBMA macromonomer were characterized by using 1H NMR. It was found that the resulted PBMA macromonomer has highly isotactic properties and the PMAA macromonomer has an end vinyl group on per polymer chain. The monodisperse polymeric microspheres, which consisted of polystyrene cores and PMAA branches on their surfaces, were prepared by the dispersion copolymerization of styrene with the PMAA macromonomer in an ethanol/water mixed solvent. It was found that the concentration of the PMAA macromonomer would affect the microsphere formation, the morphology and its size in the copolymerization system.

SYNTHETIC STUDIES ON BLOOD COMPATIBLE BIOMATERIALSⅡ. SYNTHESIS OF POLY(ETHYLENEGLYCOL MONOMETHYLLTHER ) METHACRYLATE AND ANTITHROMBOGENICITY OF ITS COPOLYMERS

Poly （ethyleneglycol monomethylether） methacrylate （PEGMM）was synthesized by means of the reaction of methacrylyl chloride with sodium monomethylpolyethyleneglycoxide and was characterized by FTIR,;H-NMR,and ultraviolet spectrometries. A series of poly （vinyl alcohol）-graft-PEGMM （PVA-g-PEGMM ）and methyl methacrylate-PEGMM copolymer （PMMA-PEGMM） were prepared and tested for antithrombogenicity in vitro. The results indicate that the antithrombogenicity of the copolymers basically increases with the increasing of the DP of polyoxyethylene （POE） chain and tends to a plateau after the DP around 114,i.e. the long chain structure of POE is favourable to the antithrombogenicityof its copolymers ;moreover, the extent of the improvement ofantithrombogenicity also relates to the PEGMM content of the copolymers and the kind of the matrix that the POE chains are located on. These results are consistent with the anticipation of the hypothesis of maintaining proteins normal conformations for blood compatible bioraaterials.

Thermosensitive Particles with Unusual Morphology Prepared by Dispersion Copolymerization

The monodispersed polymeric particles with an unusual structure were prepared by the dispersion copolymerization of acrylonitrile/styrene（AN/St） in mixed solvents of ethanol/water by using the poly（N-isopropylacrylamide） （PNIPAAm） macromonomer as a reaction stabilizer. It was found that the AN monomer plays a key role in the formation of the particles with special morphology analyzed via scanning electron microscopy （SEM）. The reaction parameters have remarkable influences on the particle size and morphology. The particles possess a thermosensitive property according to the result of laser light scattering（LLS）.

SYNTHESIS AND CHARACTERIZATION OF REACTIVE GRAFT COPOLYMER PDMS-g-(PEO-OH)

A new reactive graft copolymer, poly (dimethyl siloxane)-graft-omega-hydroxyl-poly (ethylene oxide) (PDMS-g-(PEO-OH)), was synthesized by the hydrosilylation reaction of alpha, omega-bifunctional PEO macromonomer (CH2=CH-CH2-PEO-OH) with poly (hydromethylsiloxane) (PHMS). The obtained copolymer, exhibited the expected comblike structure as indicated by the result of detailed characterization and the needed reactivity as demonstrated by the result of esterification between PDMS-g-(PEO-OH) and aminoacetic acid. This reactive graft copolymer is expected to be very useful in the preparation of new bioactive polymer materials.

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 OF HETEROARM STAR POLYMERS COMPRISING POLY(4-METHYLPHENYL VINYL SULFOXIDE) SEGMENT BY LIVING ANIONIC POLYMERIZATION

A series of 3-arm ABC and AA＇B and 4-arm ABCD, AA＇BC and AA＇A＂B heteroarm star polymers comprising one poly（4-methylphenyl vinyl sulfoxide） segment and other segments such as polystyrene, poly（a-methylstyrene）, poly（4-methoxystyrene） and poly（4-trimethylsilylstyrene） were synthesized by living anionic polymerization based on diphenylethylene （DPE） chemistry. The DPE-functionalized polymers were synthesized by iterative methodology, and the objective star polymers were prepared by two distinct methodologies based on anionic polymerization using DPE-functionalized polymers. The first methodology involves an addition reaction of living anionic polymer with excess DPE-functionalized polymer and a subsequent living anionic polymerization of 4-methylphenyl vinyl sulfoxide （MePVSO） initiated from the in situ formed polymer anion with two or three polymer segments. The second methodology comprises an addition reaction of DPE-functionalized polymer with excess sec-BuLi and a following anionic polymerization of MePVSO initiated from the in situ formed polymer anion and 3-methyl-1,1-diphenylpentyl anion as well. Both approaches could afford the target heteroarm star polymers with predetermined molecular weight, narrow molecular weight distribution （Mw/Mn 〈 1.03） and desired composition, evidenced by SEC, 1H-NMR and SLS analyses. These polymers can be used as model polymers to investigate structure-property relationships in heteroarm star polymers.