Takeo Kazama

Preparation and characterization of novel star-shaped copolymers having three different branches

Abstract Star-shaped copolymers having three different branches, poly(styrene), poly(dimethylsiloxane), and poly(tert-butyl methacrylate), were prepared by coupling of poly(styryl) anion with end-reactive poly(dimethylsiloxane), followed by anionic propagation of tert-butyl methacrylate. End-reactive poly(dimethylsiloxane) was prepared by anionic polymerization of hexamethylcyclotrisiloxane initiated with the lithium salt of p -(dimethylhydroxy)silyl- α -phenylstyrene. The resultant polymers were characterized by osmometry, g.p.c., 1 H-n.m.r., and found to be pure and to have narrow molecular weight distributions.

Morphology of model three-component three-arm star-shaped copolymers

Abstract The microdomain structure of a model three-component, three-arm, star-shaped copolymer consisting of polystyrene (PS), poly(dimethylsiloxane) (PDMS) and poly(tert-butyl methacrylate) (PTBMA), each of them having nearly the same weight fraction, was investigated by means of differential scanning calorimetry (d.s.c.), transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). D.s.c. results exhibiting the glass transition of PS and PTBMA and the crystallization and melting of PDMS strongly suggest the microphase separation of the three components into three microdomains. The microdomain structure is considered to be extremely complicated because the chemical junction points of the three constituent polymers must be confined on the lines where three kinds of interfaces meet. TEM and SAXS results strongly support the existence of a very regular microdomain structure with three-fold symmetry. Each of the three components possibly forms a three-dimensionally continuous network domain resulting in an ordered tricontinuous microdomain structure.

Fabrication of solid polymer electrolyte based on block-graft copolymer. 1. Precision synthesis and characterization of polystyrene-block-[poly(p-hydroxystyrene)-graft-poly(ethylene oxide))-block-polystyrene

Abstract Block-graft copolymer, poly(St)- block -[poly(HSt)- graft -poly(EO)]- block -poly(St) was prepared from styrene (St), p-tert -butoxystyrene (BuOSt), and ethylene oxide (EO) in four steps through anionic polymerization: (1) block copolymerization of St, BuOSt, and St; (2) deprotection of tert -butoxy group; (3) potassiation of phenolic OH; (4) graft copolymerization of EO initiated from phenoxide anion. The samples obtained were confirmed to have predictable number and length of graft chains as well as predictable length of backbone triblock copolymer and narrow molecular weight distributions by precise characterization using osmometry, 1 H and 13 C-NMR. The sample showed very clear microphase separation structure and the sample/LiCIO 4 complex showed high ionic conductivity. The block-graft copolymer is expected to be a new class of material for solid polymer electrolyte.

Anionic polymerization of alkyl methacrylates and molecular weight distributions of the resulting polymers

Abstract Anionic polymerizations of methyl methacrylate, n-butyl methacrylate and tert-butyl methacrylate with 1,1-diphenylhexyllithium in THF at 195 K were performed. By characterizing the resultant polymers, the controllable limits of molecular weight and molecular weight distribution were examined. Tert-butyl methacrylate gave a polymer with a high molecular weight (1.8 · 105) and narrow molecular weight distribution ( M w M n = 1.0 7 ). A well-defined block copolymer of tert-butyl methacrylate with styrene or α-methylstyrene was obtained by intermediate addition of 1,1-diphenylethylene.

Anionic polymerization of 3,5-(2,4-)dimethoxystyrene and 2,4,6-trimethoxystyrene and functionalization of the resulting polymers by lithiation

Abstract Anionic polymerizations of 3,5-dimethoxystyrene ( 1 ), 2,4-dimethoxystyrene ( 2 ), and 2,4,6-trimethoxystyrene ( 3 ) were studied in THF at 195 K using sec -butyllithium as an initiator. Initiation reactions proceeded immediately upon addition of initiator for all monomers, but the propagation rates decreased in the order of 1 2 3 . Both the monomers 1 and 2 gave the corresponding polymers having predictable molecular weights and narrow molecular weight distributions. However, the monomer 3 gave no polymer. It was confirmed that lithiation reaction of poly( 1 ) and poly( 2 ) by n -butyllithium in THF at 238 K proceeded with ease at the 4− and 3-positions of phenyl ring, respectively. Lithiated poly( 1 ) and poly( 2 ) are expected to be novel functional polymers for various applications.

Preparation and properties of poly(sec-butyl crotonate)

Abstract Poly(sec-butyl crotonate) (poly(SBC)) was prepared by anionic polymerization. 1,1-Diphenylhexyllithium was found to be an effective initiator. Poly(SBC) showed the same optical properties as poly(methyl methacrylate) (poly(MMA)) but different features: poly(SBC) had a high glass transition temperature (Tg) and very high extensibility below Tg, in comparison to poly(MMA). Poly(SBC) can be expected to find applications as an optical material having high flexibility and high service temperature.

Precision Polymerization and Polymers II. Preparation and Morphology of Star-Shaped Copolymers of the AnBn Type.

ポリスチレン (PS) とポリイソプレン (PI) からなるAnBn星型共重合体を合成するため, 4, 8, 12官能クロロシラン化合物にリビングPSとリビングPIを2段階で逐次カップリング反応させた. 1段目は1, 1-ジフェニルエチレンで末端修飾したリビングポリスチレンと結合剤との反応で, カップリング率を50%あるいはそれ以下に制御できることを確認した. 2段目はブタジエンで末端修飾したリビングポリイソプレンと1段目でのカップリング生成物との反応である. 最終生成物からGPC分取操作により星型共重合体を単離し, NMR法および膜浸透圧法により目的とする構造を有する星型共重合体が得られていることを確認した. モルフォロジー観察の結果, 腕鎖の分子量が10000程度の星型共重合体試料ではブロック共重合体と同様のミクロ相分離構造が観察されたが, 腕鎖の分子量が40000程度の試料のミクロ相分離構造では緩慢な界面が認められた. これは多重分岐と高分子量による分子運動性低下によるものと考えられる.