Synthesis and solution properties of well‐defined comb‐on‐comb graft polymers

Abstract

Well-defined comb-on-comb copolymers of styrene, isoprene, and amethyl-styrene are prepared through cascade ''grafting-onto'' methods. The polymer main chain is prepared by nitroxide-mediated radical polymerization while the branches are prepared by anionic polymerization. The ''grafting-onto'' approach employs the coupling chemistry of macromolecular anions, such as polystyryllithium, polyisoprenyllithium, or poly(a-methylstyryl)lithium, toward either benzyl chloride or epoxy ring on precursor backbones. Thus a series of ABA-, ABB-, and ABC-type comb-on-comb copolymers are prepared and characterized by gel permeation chromatography equipped with a multi-angle laser light scattering detector and a viscometer. Unusual ''U-shaped'' dependences of radius of gyration, R g , on molecular weight are observed for comb-on-comb products, which are attributable to delayed elution of the densely grafted copolymers from GPC columns. The result also shows that the comb-on-comb copolymers exhibit morphologies from hard sphere to cylindrical rod, depending on the length ratio of the main chain to the branches. V V C 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: [5518][5519][5520][5521][5522][5523][5524][5525][5526][5527] 2008

Synthesis of graft polymers with poly(isoprene) as main chain by living anionic polymerization mechanism

“…The topologies of graft polymers usually included the comb, comb‐on‐comb and star‐comb, H‐shaped and super H‐shaped,19 V‐shaped,20 and Y‐shaped 21. However, the main chains of the graft copolymers were typically comprised of PEO, 7b, 18 PS,22 poly(acrylic acid), 7g poly(‐hydroxyethyl methacrylate)23 and so on, and poly(isoprene) (PI) was difficultly and rarely constructed into the main chain of graft polymers because the PI segment with controlled molecular weight and low PDIs was always synthesized by LAP mechanism and there were no accessible functional groups on PI for further modification 24…”

Synthesis of well‐defined pH‐responsive PPEGMEA‐g‐P2VP double hydrophilic graft copolymer via sequential SET‐LRP and ATRP

“…Recently, significant attention has been paid to the synthesis of well‐defined graft polymers with predefined molecular weight, narrow molecular weight distribution, and high degree of chain end functionalization due to their unique and interesting properties, behaviors, and morphologies in solution as well as bulk 27–31. The structure of a graft (co)polymer is defined by the following four parameters: (1) chemical composition; (2) molecular weight of backbone; (3) molecular weight of side chain; (4) distance between side chains; and (5) the number of grafting points along the backbone.…”

Synthesis of well‐defined comb‐like graft (co)polymers by nucleophilic substitution reaction between living polymers and polyhalohydrocarbon

“…Introduction of halogen groups has long been considered as an effective way in coupling reaction. In the early 1970s, Cl‐ or Br‐methylated polystyrene was utilized in branched polymer synthesis,10, 17–19 then later, by polymerization of protected monomer followed by posthalogenation, or directly polymerization of chloromethylstyrene,20, 21 well‐defined poly(halomethyl styrene) was produced for graft polymer synthesis 8, 9. Hydrosilylation of vinyl containing polymers (poly( p ‐(3‐butenyl)styrene),12 or polybutadiene with 1,2‐unit,13, 14 was realized to incorporate SiCl groups using chlorohydrosilane for graft polymers with Si linkage.…”