General and Facile Approach to Exact Graft Copolymers by Iterative Methodology Using Living Anionic In-Chain-Functionalized AB Diblock Copolymers as Key Building Blocks

Abstract

A variety of exact graft copolymers, such as poly(tert-butyl methacrylate)-exact graft-polystyrene (PS), poly(ferrocenylmethyl methacrylate)-exact graft-PS, and poly(2-vinylpyridine)-exact graft-PS, have been successfully synthesized by developing a novel stepwise iterative methodology based on a new concept utilizing living in-chain-(3-tert-butyldimethylsilyloxymethylphenyl) (SiOMP)-functionalized AB diblock copolymers as key building blocks. The methodology basically involves three reaction steps in each iterative process, i.e., (1) living anionic block copolymerization to prepare a living in-chain-SiOMP-functionalized AB diblock copolymer, (2) a transformation reaction of the SiOMP group into an α-phenyl acrylate (PA) function, and (3) a 1:1-addition reaction of the resulting in-chain-PA-functionalized AB diblock copolymer with a living in-chain-SiOMP-functionalized AB diblock copolymer separately prepared to link the two block copolymer chains. By performing the same iterative process involving steps 1–3 several times, the above-mentioned exact graft copolymers having three to five PS branches were synthesized. The resulting polymers were all well-defined in architecture and precisely controlled in chain structure.

Precise Synthesis of Block Polymers Composed of Three or More Blocks by Specially Designed Linking Methodologies in Conjunction with Living Anionic Polymerization System

“…It is also disadvantageous that the formation of an unstable Si-O bond is formed in the linking reaction between the silyl chloride function and the living polymer of MMA or other alkyl methacrylate monomers. These synthetic problems have been overcome by developing a new alternative linking methodology using an α-phenylacrylate linking reaction site [53][54][55][56][57][58].…”

Chain Architecture as an Orthogonal Parameter To Influence Block Copolymer Morphology. Synthesis and Characterization of Hyperbranched Block Copolymers: HyperBlocks

“…Predominantly these studies have been aimed at understanding the impact of chain branching upon the melt rheology of such polymers. Commonly studied branched architectures include the simplest branched structure, star polymers [1][2][3][4][5] , and increasingly complex architectures such as miktoarm stars 6,7 , graft/comb polymers [8][9][10][11][12][13] , H-shaped polymers [14][15][16][17] and dendritically long-chain branched polymers [18][19][20][21][22][23][24][25][26][27][28] . Chain-branching in block copolymers has also been explored with a view to understand the influence of architecture upon phase separation.…”

Phase Structure of the Exact Graft Copolymer Synthesized by Iterative Methodology Based on Living Anionic Polymerization

“…The availability of the EGC samples provides the mean to examine the phase structure of graft copolymer for unambiguous comparison with that of the linear bcp to resolve the molecular architecture effect on the self‐assembly behavior of copolymers in detail. In this study, we investigate the phase behavior of the EGC composed of P2VP backbone and PS grafts (denoted as “EG(P2VP‐PS) n ”) synthesized by the anionic polymerization using iterative approach . The copolymers possess different numbers of junction points of PS graft per molecule under fixed graft length and length between the junction points.…”

“…Graft copolymer is composed of a backbone grafted with chemically different side chains. Its molecular architecture is characterized by four parameters, namely, the length or molecular weight of the backbone, the length of the graft chain ( l g ), the separation distance between the junction points in the backbone (ε), and the number of junction points or grafts per molecule ( n ) . The complex combination of these molecular parameters may result in a broad spectrum of phase behavior which deviates greatly from that of the linear bcp in terms of the domain spacing and the phase boundaries associated with the order–order and order–disorder transition.…”

“…Hirao et al later extended this iterative concept to synthesize the graft copolymers composed of poly(2‐vinyl pyridine) (P2VP) backbone and PS grafts with precisely defined molecular parameters. The graft copolymers thus synthesized are specifically called “exact graft copolymer (EGC)” to distinguish from the system without rigorous architectural control . The availability of the EGC samples provides the mean to examine the phase structure of graft copolymer for unambiguous comparison with that of the linear bcp to resolve the molecular architecture effect on the self‐assembly behavior of copolymers in detail.…”