CONTROLLED SYNTHESIS OF AMPHIPHILIC BLOCK POLYMERS HAVING GLUCOSE RESIDUES AND THEIR STRUCTURE FORMATION

Vinyl ether (VE)-based amphiphilic block copolymers with D-glucose residues as hydrophilicpendants were synthesized by CH_3 CH(OiBu)Cl/ZnI_2-initiated sequential living cationic copolymerization of3-O-(vinyloxy)ethyl-1, 2:5, 6-di-O-isopropylidene-D-glucofuranose (IGVE) and isobutyl VE (IBVE ) andsubsequent deprotection. The precursor block copolymers had a narrow molecular weight distribution(M_w/M_n～1.1) and a controlled segmental composition. The solubility characteristics of the amphiphiliccopolymer depended strongly on composition. Their solvent-cast thin films were examined, under atransmission electron microscope, and could be seen to exhibit various microphase-separated surfacemorphologies such as spheres, cylinders, and lamellae, depending on composition. The amphiphiliccopolymers with the appropriate segmental composition were found to form a stable monolayer at the air-water interface, which was successfully transferred onto a substrate by the Langmuir-Blodgett (LB)technique. The layered strucfure of the built-up LB films was controlled by blending the homopolymer.

A strong adhesive block polymer coating for antifouling of large molecular weight protein

Some proteins secreted by microorganisms have large molecular weights. We report here an approach to prepare coating by multilayer polymers for antifouling of proteins, especially the proteins with a large molecular weight.Stainless steel was used as the model substrate. The substrate was first coated with a hybrid polymer film, which was formed by simultaneous hydrolytic polycondensation of 3-aminopropyltriethoxysilane and polymerization of dopamine(HPAPD). After grafting the macroinitiator 2-bromoisobutyryl bromide, the block polymer brushes PMMA-b-PHEMA were grafted. Three proteins were used to test protein adsorption and antifouling behavior of the coating, including recombinant green fluorescent(54 k Da), recombinant R-transaminase(2 × 90 k Da), and recombinant catalase(4 × 98 k Da). It is demonstrated that the block polymer brushes not only can prevent the adsorption of small molecular weight proteins, but also can significantly reduce the adsorption of the large molecular weight proteins.

Syntheses and Studies of PEG-b-PNIPA Block Polymers

The ABA block copolymers of polyethylene glycol(PEG) as B block and poly N isopropylacrylamide(PNIPA) as A block were synthesized by means of radical polymerization with one step. The block polymers exhibit thermosensitive behavior at a higher LCST temperature than homopolymer of NIPA.

Alternating Copolymerization of Epoxides and Isothiocyanates to Diverse Functional Polythioimidocarbonates and Related Block Polymers

Synthesis of diverse polythioimidocarbonates via ring-opening copolymerization of epoxides and isothiocyanates catalyzed by organoboron catalyst was reported herein.Both aromatic and aliphatic isothiocyanates underwent successful copolymerization with terminal and internal epoxides,allowing for the precise tuning of the performance of the resultant copolymers over a broad range.The wide scope of available isothiocyanates and epoxides enables the direct construction of sulfur-containing functional polymers featuring both high glass transition temperature and refractive index.Additionally,it was observed that aromatic isothiocyanates polymerize much faster than aliphatic ones,and the reactivity difference facilitated the one-step synthesis of block polymers from mixed aromatic isothiocyanates,aliphatic isothiocyanates and epoxides due to the preferential incorporation of aromatic isothiocyanates over the aliphatic analogues during their alternating copolymerization with epoxides.The produced polythioimidocarbonates can be used as positive resists for electron beam lithography(sensitivity of 130μC/cm^(2) and contrast of 1.53 for poly(CHO-alt-EITC)).Coupling with their high refractive index(1.58—1.68),polythioimidocarbonates might find functional applications in optics.These results render ring-opening copolymerization of epoxides and isothiocyanates a facile route to enrich functional polymer library.

Rational design of phosphonate/quaternary amine block polymer as an high-efficiency antibacterial coating for metallic substrates

Developing advanced technologies to address the bacterial associated infections is an urgent requirement for metallic implants and devices.Here,we report a novel phosphonate/quaternary amine block polymer as the high-efficiency antibacterial coating for metallic substrates.Three pDEMMP-b-pTMAEMA block polymers that bearing identical phosphonate segments(repeat units of 15)but varied cationic segments(repeat units of 8,45,and 70)were precisely prepared.Stable cationic polymer coatings were constructed on TC4 substrates based on the strong covalent binding between phosphonate group and metallic substrate.Robust relationship between the segment chain length of the polymer coating and the antibacterial property endowed to the substrates have been established based on quantitative and qualitative evaluations.Results showed that the antibacterial rate of the modified TC4 surface were 95.8%of S.aureus and 92.9%of E.coli cells attached.Interestingly,unlike the cationic free polymer or cationic hydrogels,the surface anchored cationic polymers do compromise the viability of the attached C2C12 cells but without significant cytotoxicity.In addition,the phosphonate/quate rnary amine block polymers can be easily constructed on titanium,stainless steel,and Ni/Cr alloy with significantly improved antibacterial property,indicating the generality of the block polymer for surface antibacterial modification of bio-metals.

SYNTHESIS AND CHARACTERIZATION OF WELL-DEFINED BLOCK COPOLYMERS CONTAINING PENDANT,SELF-COMPLEMENTARY QUADRUPLE HYDROGEN BONDING SITES

The title block copolymer (defined as PSUEA) containing pendant,self-complementary quadruple hydrogen bonding sites has been prepared successfully by three steps.First,poly(styrene-b-2-hydroxyethyl acrylate) (defined as PSHEA) was prepared by living radical polymerizing 2-hydroxyethyl acrylate (HEA) initiated by polystyrene (PSt) macro- initiator,which was prepared via nitroxide-mediated polymerization (NMP) technique.After treated by excessive 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI),...

Spectroscopic investigation on chirality transfer in additive-driven self-assembly of block polymers

Chiral supramolecules prepared by the additive-driven self-assembly of block copolymers provide a facile method to construct helical nanostructures. In this study, we investigated the chiral transfer from chiral tartaric acid to poly（styrene）-b-poly（ethylene oxide） using small-angle X-ray scattering,transmission electron microscopy, circular dichroism, and vibrational circular dichroism. The results showed that the chirality was transferred to both the segments of block copolymer irrespective of the interaction with the chiral additives and formation of helical phase structure. However, the chirality transfer was carried out using different methods： for poly（ethylene oxide） segments, the chirality transfer was carried out via direct hydrogen bond formation; for polystyrene segments, the chirality transfer was carried out via the cooperative motion of block copolymers during the thermal annealing.

Synthesis of Well-Defined Dendritic-Linear Diblock and Triblock Copolymers by Controlled Free Radical Polymerization

The design and synthesis of novel dendritic-linear block copolymers were described. The copolymers were synthesized by atom transfer radical polymerization (ATRP) using dendritic polyarylether 2-bromoisobutyrate macroinitiator. ATRP carried out in bulk with CuBr/bipy catalyst at 120癈, yielded well-defined block copolymers with polydispersities less than 1.36.

AMPHIPHILIC STAR-BLOCK COPOLYMERS BY IODIDE-MEDIATED RADICAL POLYMERIZATION

Amphiphilic star-block copolymers composed of polystyrene and poly（acrylic acid） were synthesized by iodide- mediated radical polymerization. Firstly, free radical polymerization of styrene was carried out with AIBN as initiator and 1,1,1-trimethyolpropane tri（2-iodoisobutyrate） as chain transfer agent, giving iodine atom ended star-shaped polystyrene with three arm chains, R（polystyrene）3. Secondly, tert-butyl acrylate was polymerization using polystyrene obtained as macro-chain transfer agent, and star-block copolymer, R（polystyrene-b-poly（tert-butyl acrylate））3 with controlled molecular weight was obtained. Finally, amphiphilic star-block copolymer, R（polystyrene-b-poly（acrylic acid））3 was obtained by hydrolysis of R（polystyrene-b-poly（tert-butyl acrylate））3 under acidic condition.

An Observation on the Microphase Separation of Poly(methyl methacrylate)-block-Polystyrene Copolymer

The phase behavior of a well-defined poly(methyl methacrylate)- b- polystyrene block copolymer was studied by transmission electron microscope. The results show that a microphase transition may have occurred in the copolymer film. A kind of lamellae and an ordered bicontinuous double-diamond morphology are observed clearly. The lamellar morphology reveals a larger period of about 400 nm.

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-caprolactone(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 pre-polymer(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 OF BLOCK COPOLYMER BY INTEGRATED LIVING ANIONIC POLYMERIZATION-ATOM TRANSFER RADICAL POLYMERIZATION(ATRP)

Alpha-trichloroacetoxy terminated polystyrene oligomer (PS-CH2CH2OCOCCl3) and poly-(styrene-b-butadiene) oligomer [P(S-b-B)-CH2CH2OCOCCl3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator. Then the PS-CH2CH2OCOCCl3 (PS-Cl-3) or P(S-b-B)-CH2CH2O-COCCl3 (PSB-Cl-3) was used as the macroinitiator in the polymerization of(meth)acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared by the integrated living anionic polymerization (LAP)-atom transfer radical polymerization (ATRP). The structures of the PSB-Cl-3 and the P(S-b-MMA) were identified by FTIR and H-1-NMR spectrum, respectively. A new way to design block copolymers (the combination of LAP and ATRP) was developed.

SYNTHESES OF STYRENE-METHYL METHACRYLATE BLOCK COPOLYMER BY POLYAZOAMIDE AS INITIATOR

Polyazoamide（PAA） was used as initiator to prepare block copolymer P（MMA-b-St） byfree radical polymerization. The fraction of block copolymer was about 50%. The structureof the block-copolymer was characterized by IR and the results of;H-NMR and GPCshowed that the content of the block and the molecular weight （M;） of the prepolymerand block copolymer could be controlled by varying the mol ratio of styrene/PAA andMMA/prepolymer. DSC and TEM results revealed that the block copolymer has twoseparated glass transition temperatures and phase separation within the domain structure.

WHOLLY-AROMATIC THERMOTROPIC LIQUID CRYSTALLINE POLYMER AND ITS BLOCK COPOLYMER

A wholly-aromatic thermotropic liquid crystalline polymer (WATLCP) composed of p-hydroxybenzoic acid (HBA), 4,4'-dihydroxy bisphenyl (BP), terephthalic acid (TPA), m-phthalic acid (MPA) was synthesized. It was symbolized by BP-LCP. Using a similar method, a new copolymer BP-PSF was prepared. BP-PSF has a semi-flexible chain polysulfone and a rigid-rod chain like BP-LCP. By FT-IR, polarizing microscope and DSC technique, the structures and properties of BP-LCP and BP-PSF were studied.

SYNTHESIS OF BLOCK COPOLYMER FROM 5,6 -BENZO-2-METHYLENE-1,3-DIOXEPANE AND METHYL ACRYLATE VIA ATOM TRANSFER RADICAL POLYMERIZATION

Poly(methyl acrylate)-b-poly(5,6-benzo-2-methylene-1,3-dioxepane) (PMA-b-PBMDO) was synthesized by two-step atom transfer radical polymerization (ATRP). Firstly, ATRP of methyl acrylate (MA) was realized using ethyl alpha-bromobutyrate (EBrB) as initiator in the presence of CuBr/2,2'-bipyridine. After isolation, poly(methyl acrylate) with terminal bromine (PMA-Br) was synthesized. Secondly, the resulting PMA-Br was used as a macromolecular initiator in the ATRP of BMDO. The structure of block copolymer was characterized by H-1-NMR spectroscopy. Molecular weight and molecular weight distribution were determined on a gel permeation chromatograph (GPC).

Synthesis of Dendritic-Linear Block Copolymers by Atom Transfer Radical Polymerization

The dendritic polyarylether 2-bromoisobutyrate as the macromolecular initiator for the controlled free radical polymerization of styrene was investigated. The polymerization was carried out with CuBr/2,2 ' -bipyridine catalyst at 110 degreesC. It is found that the hybrid dendritic-linear block copolymers possess well-defined molecular weights and low polydispersities.

Morphology Control of Polymer Microspheres Containing Block Copolymers with Seed Polymerization

Microspheres based on binary polymer blend consisting of polystyrene (PSt), poly (methyl methacrylate) (PMMA), block copolymer comprising PSt and PMMA subunits, and ternary polymer blend consisting of PSt, PMMA, and block copolymer were fabricated by a solvent evaporation method, in which a polymer solution in dichloromethane was dispersed in water phase with the aid of a homogenizer to obtain an O/W emulsion followed by solvent evaporation with agitation to solidify the polymer. In the case of ternary blend, the effect of block copolymer content on the morphology of resulting spheres was investigated. Ternary blends afforded the bi-compartmental morphologies, the intermediate morphology between Janus and core-shell, which was confirmed by TEM observation. Seed polymerization of St or MMA was also carried out utilizing the resulting microspheres as seed particles in order to control the shape, and the surface morphology of particles. The particles with snowman-like morphology were obtained by seed polymerization of St using PSt/PMMA binary blend microspheres as seed particles. Surface roughness was controlled by the polymerization of MMA in the block copolymer seed, and that of St in the ternary blend seed.

Synthesis and characterization of H-type amphiphilic liquid crystalline block copolymers by ATRP

H-type amphiphilic liquid crystalline block copolymers containing azobenzene were synthesized by atom transfer radical polymerization （ATRP）. Macroinitiators prepared by the esterification between poly（ethylene oxide） （PEG） and 2,2-dichloroacetyl chloride were utilized to initiate the polymerization of 6-[4-（4-ethoxyphenylazo）phenoxy]hexyl rnethacrylate （M6C）. The resulting macroinitiators and block copolymers were characterized by ^1H NMR, gel permeation chromatography （GPC）. Polarizing optical microscopy （POM） and differential scanning calorimetry （DSC） preliminarily revealed the liquid crystalline property of these block copolymers. This series of liquid crystalline block copolymers are promising in some areas, such as optical data storage, optical switch, and molecular devices.