Model Block−Graft Copolymer via Anionic Living Polymerization:  Preparation and Characterization of [Poly((4-vinylphenyl)dimethylvinylsilane)- graft-polyisoprene]-block-polystyrene

Abstract

A model graft copolymer that has well-defined length, number, and position of grafts was prepared via anionic living polymerization. (4-Vinylphenyl)dimethylvinylsilane (VS) was anionically polymerized by cumylcesium in THF at -78°C for 20 min under a pressure of 10 -5 mmHg, and subsequent addition of styrene (St) yielded a PVS-b-PSt block copolymer that could be used as a backbone molecule. PVS has a silylvinyl group on the side chain that converts chemical links between backbone and grafts. Isoprene (Is) was anionically polymerized to yield living polyisoprene, and the resultant PIs -Cs + and PIs -Li + solutions were added to THF and benzene solutions of PVS-b-PSt, respectively. After 24 h, backbone coupling was terminated to yield [poly((4-vinylphenyl)dimethylvinylsilane)-graft-polyisoprene]-block-polystyrene. The three graft copolymers were prepared. Molecular characterization was carried out by GPC measurement, osmometry, and sedimentation pattern. The Mn and Mw/Mn values of the backbone, grafts, and graft copolymers were determined. The number of grafts per backbone molecule was found to be 10.0, 10.9, and 12.5 for the three graft copolymers, and the position of the grafts was set to the end of the backbone molecule. Spacing and its distribution of the graft points on a backbone molecule were also discussed. Three benzene-cast films formed clear microphase-separated structures, such as spherical and lamellar structures. The composition dependence on the morphology of the graft copolymers was found to differ from that of common block copolymers. These results suggest that the apparent volume fraction of grafts is much larger than the real volume fraction, because the grafts became crowded in the vicinity of the backbone molecule.

Grafting of oligopeptide on poly(aminostyrene)s and characterization of the polymers

“…In the case of a "grafting onto process" where polyisoprenyllithium (PIs Ϫ ) reacts with polystyreneblock-poly (4-vinylphenyl)dimethylvinylsilane to yield polystyrene-block-{poly[(4-vinylphenyl)dimethylvinylsilane]-graft-polyisoprene}, the degree of grafting (the spacing of the graft points on a backbone molecule) could not approach a value of 100% but approached a value of less than 32%. 1 The nonquantitative coupling was due to steric hindrance and electro-static repulsion between the PIs Ϫ carbanions and the negative charges of the backbone molecule. In case of a "grafting from process" where ethylene oxide is polymerized by polystyrene-block-poly(p-styrylpotassium hydroxide)-block-polystyrene to yield polystyrene-block-[poly(p-hydroxystyrene)-graft-poly(ethylene oxide)]-block-polystyrene, the degree of grafting could not approach a value of 100% but approached a value of less than 50%.…”

“…Poly(aminostyrene)s (PAS) 1 provide an interesting example of stable intermediates of final polymers, because they can be used as the backbone chains of graft copolymers, 1,2 as the prepolymer of crosslinked polymers, 3,4 and for introducing other functions. 5,6 When PAS is used as a backbone molecule of high-performance graft copolymers, two problems must be overcome.…”

Development of Sub-5 nm Patterning by Directed Self-Assembly using Multiblock Copolymers

“…Various kinds of multiblock copolymer such as ABC [9][10][11], ABCA [12], ABCD [13], ABC miktoarm star copolymers [14][15][16][17][18], ABn miktoarm graft copolymers [19] and etc. were synthesized for the morphological study for the academic viewpoints.…”

Selective complete decomposition of poly(n‐hexylisocyanate) and its use in a new molecular design method

“…Although many nonlinear block copolymers such as hetero‐star block copolymers have been prepared,1–6 there have been a few reports of the block copolymers having rod‐like polymers such as poly(3‐hexylthiophene)7–9 and poly( n ‐hexylisocyanate)10 (PHIC) as a component. A major reason for the few reports is attributable to the difficulties surrounding precise preparation of the block copolymers.…”