Block copolymers comprising poly(ethylene oxide) and poly(hydroxyethyl methacrylate) blocks: synthesis and characterization

Monofunctional poly(ethylene oxide) macroinitiators with a molecular weight of 2000, 5000, 10?000, 20?000 and bifunctional poly(ethylene oxide) macroinitiators with a molecular weight of 20?000 were used for the atom transfer radical polymerisation (ATRP) of hydroxyethyl methacrylate (HEMA) in ethylene glycol as a solvent. The polymerisation proceeds in a controlled way up to high conversions. The molecular weight of the obtained copolymers increases linearly with conversion. A high rate of polymerisation was observed for the ATRP of HEMA. The effect of the poly(ethylene oxide) moiety on the course of the reaction is limited to solvating effects. The surface analysis of poly(ethylene oxide)/poly(hydroxyethyl methacrylate) block copolymers by means of atomic force microscopy in tapping mode using phase imaging shows phase separated domains with characteristic features related to the volume fraction of the respective blocks.     

Preparation of Some Br-ended MMA Three Arm Star Block Copolymers via ATRP and Other Amphiphilic Hydroxyl Ended Ones

MMA-St, MMA-VA, MMA-St-MA, and MMA-VA-n-BuMA three arm star block copolymers were prepared via ATRP by using trifunctional initiator. TMED CuBr catalytic system was involved in such polymerization processes at 90°C. Subsequent transformation of the bromine ends to hydroxyl ones were carried out on MMA-St and MMA-VA copolymers as two different examples, and two variable routes were involved in the transformation processes using ethanolamine and silver, respectively.     

聚偶氮酰胺的合成及表征

本文应用Ritter反应机理,以偶氮二异丁腈(AIBN)和三聚乙醛为主要原料,在浓硫酸催化作用下合成新型大分子引发剂—聚偶氮酰胺(PAA),并用IR、UV、~1H-NMR、GPC等方法表征结构,用DSC研究其热分解反应动力学。     

Preparation of Monomer Casting Nylon-6-b-Polydimethylsiloxane Copolymers with Enhanced Mechanical and Surface Properties

Nylon-6-b-polydimethylsiloxane copolymer was synthesized with macroinitiator through in situ polymerization. The macroinitiator with two chain-growing centers per molecule is based on hydroxyl terminated polydimethylsiloxane (PDMS) functionalized with diisocyanate. The influence of PDMS contents on the properties of copolymers was studied. Differential scanning calorimetry and X-ray diffraction were used to investigate the melting temperature, crystallization temperature and crystal form of samples, and the results showed that the crystallinity of polymers decreased. The mechanical properties of samples were studied by notched-impact testing and tension test. The notched impact strength was improved by 200% with PDMS concentration up to 4?wt%. The form of scaly was seen by scanning electron microscope proved the improvements of the impact strength of the copolymer. The water contact angles test showed that the surface tension of copolymers decreased with the PDMS content increasing and the surface of copolymer changed from hydrophilic to hydrophobic.     

Synthesis of block copolymers from PDMS macroinitiators

The synthesis of polystyrene‐b‐polydimethylsiloxane‐b‐polystyrene (PSt‐b‐PDMS‐b‐PSt) copolymers is described. Commercially available difunctional PDMS containing vinylsilyl terminal species was reacted with hydrogen bromide resulting in the PDMS macroinitiators. The terminal alkyl bromide groups were then used as initiators for atom transfer radical polymerization (ATRP) to produce block copolymers. Using this technique, triblock copolymers consisting of a PDMS centre block and polystyrene terminal blocks were synthesized. ATRP of St from those macroinitiators showed linear increases in M_n with conversion, demonstrating the effectiveness of ATRP to synthesize a variety of inorganic/organic polymer hybrids. Copyright © 2004 Society of Chemical Industry     

Atom transfer radical polymerization of some vinyl monomers catalyzed by imine macrocycle copper (I) complex

Summary Imine macrocyclic ligand (M₁) was used in conjunction with CuBr as novel catalytic system in atom transfer radical polymerization (ATRP) of methylmethacrylate (MMA), butylmethacrylate (n-BuMA) and 2- dimethylaminoethylmethacrylate (DMAEMA). Two different initiators were involved such as Br-methoxypolyoxyethylene macroinitiator and 1, 3, 5-(2-bromo-2‘-methylpropionato) benzene three arm star initiator. The polymerization reactions were conducted at 90 °C in toluene. The macrocyclic ligand M₁ demonstrated peculiar behavior which was monitored by the GPC measurements whether with respect to the polydispersities or the molar masses. High molar masses than expected were obtained except incase of DMAEMA monomer. The structures of the formed polymers were proven via ¹HNMR.     

Polymerization of methyl methacrylate with mechano-chemically synthesized macroinitiators

The polymerization of methyl methacrylate initiated by acrylonitrile- based homopolymers and copolymers synthesized mechanochemically by vibratory milling has been studied. The factors influencing the conversion and poly(methyl mehtacrylate) molecular weight are discussed. Both characteristics depend on polymerization parameters (reaction time, temperature and initiator concentration) as well as on macroinitiator synthesis conditions (duration of the vibratory milling process, comonomer ratio). The polymerization product consists of poly(methyl methacrylate) and small amounts of poly(acrylonitrile-g-methyl methacrylate)copolymer.     

多嵌段共聚物的ATRP合成及表征

采用末端功能化的聚(二甲基硅氧烷)大分子(Br-PDMS-Br)为引发剂,CuCl为催化荆,2,2'-联吡啶(bpy)为配体,通过原子转移自由基聚合(ATRP)法,合成出结构明确的多嵌段共聚物聚甲基丙烯酸丁酯-b-聚二甲基硅氧烷-b-聚甲基丙烯酸丁酯和聚苯乙烯-b-聚甲基丙烯酸丁酯-b-聚二甲基硅氧烷-b-聚甲基丙烯酸...