A Block Copolymer from Polystyrene and Columnar Liquid-Crystalline Poly(diethylsiloxane)

Abstract

A block copolymer from polystyrene (PS) and poly(diethylsiloxane) (PDES) has been synthesized by sequential anionic polymerization. By DSC, the PDES block was shown to exist in the columnar mesophase at ambient temperatures. By transmission electron microscopy and scanning force microscopy on thin films, the block copolymer was shown to build regular structures, showing a large periodicity, which is unusual for relatively low molecular weight block copolymers and must be ascribed to the fact that the PDES block exists in the mesophase.

Thermal stabilization of poly(3‐hydroxybutyrate) by poly(glycidyl methacrylate)

“…[22][23][24][25][26][27][28][29] Liquid crystalline block copolymers have proved to be an effective compatibilizer in polymer-blend systems of TLCPs with a thermoplastic matrix and also have proved to be efficient in the control of the microphase dimension of the blend system of TL-CPs/thermoplastics. 3,33 Different approaches to the preparation of liquid crystalline block copolymers have been reported, including (1) living and quasi-living polymerization such as anionic, 34,35 cationic, 36 ring-opening metathesis, 37 and group transfer 38 ; (2) polycondensation 39,40 ; (3) the use of macroinitiators 41,42 ; (4) transfer agents 43 ; (5) coupling of end-functionalized homopolymers 44,45 ; and (6) polymer-analogous reactions of AB-type prepolymers. Thus, the liquid crystalline block copolymer can serve as a bridge between TLCPs and the thermoplastic matrix.…”

Block copolymers and networks from polybutadiene and polydiethylsiloxane

“…Figure 1 shows a DSC heating thermogram of a PB-b-PDES copolymer containing 40 wt.-% PB. As in the case of PS-b-PDES copolymers, the fraction of the b polymorph is much smaller than in the case of homo-PDES of the same molecular weight, indicating chain folding in the PDES block [1,2]. Figure 2 shows DSC heating scans of the star block copolymer #4 and the network derived therefrom.…”

“…The somewhat unclear separation of the PB and the PDES domains may be connected to the fact that, even at -140 8C, a-PDES is relatively soft [12] and to the lower surface tension of PDES, compared to PB. (In the case of thin PS-b-PDES films, the PDES phase was observed as protrusions [1].) Both may cause smearing out of PDES chains during microtoming.…”

“…Even in the case of low PS content, PS cylinders tend to organize in sheets [1,2]. Since the glass transition temperature of PS (T g L 100 8C) is higher than the isotropization temperature of the PDES block (T i a ca.…”

Synthesis and characterization of block copolymers containing PC segments and PHTH‐6 mesogenic units

“…So, studies on the synthesis, structure, and properties of the liquid crystalline block copolymers are of considerable interest for potential application and theoretical research as well 3, 33. Different approaches to the preparation of liquid crystalline block copolymers have been reported, including (1) living and quasi‐living polymerization such as anionic,34, 35 cationic,36 ring‐opening metathesis,37 and group transfer38; (2) polycondensation39, 40; (3) the use of macroinitiators41, 42; (4) transfer agents43; (5) coupling of end‐functionalized homopolymers44, 45; and (6) polymer‐analogous reactions of AB‐type prepolymers 46, 47…”