Model block-graft copolymer via anionic living polymerization: Preparation and characterization of polystyrene-block-[poly(p-hydroxystyrene)-graft-poly(ethylene oxide)]-block-polystyrene

Abstract

A model graft copolymer in which position of graft points was set to the center of a backbone molecule was prepared via anionic living polymerization. Polystyrene‐block‐poly(p‐tert‐butoxystyrene)‐block‐polystyrene (PSt‐b‐PBSt‐b‐PSt) was prepared by three‐stage sequential addition. The tert‐butyl group was removed from PBSt by hydrogen bromide to yield PSt‐b‐PHSt‐b‐PSt, having a poly(p‐hydroxystyrene) (PHSt) block. The hydroxyl group of PHSt was reacted with dimeric potassium dianions of 1, 1‐diphenylethylene (DPE‐K) or cumyl potassium (cumyl K) to yield the corresponding macromolecular initiators of PSt‐b‐PHSt−K+‐b‐PSt containing the potassium alkoxide ion of PHSt. The newly formed alkoxide groups and remaining initiators of DPE‐K or cumyl K are capable of initiating the additionally introduced ethylene oxide (EO). Thus, two block–graft copolymers of polystyrene‐block‐[poly(p‐hydroxystyrene)‐graft‐poly(ethylene oxide)]‐block‐polystyrene (PSt‐b‐(PHSt‐g‐PEO)‐b‐PSt) were prepared by a “grafting from” process (backbone initiation). A PSt‐b‐PHSt‐b‐PSt backbone (Mn = 1.75 × 105 by osmometry and Mw/Mn = 1.08 by GPC), and two PSt‐b‐(PHSt‐g‐PEO)‐b‐PSt block–graft copolymers (Mn = 2.45 × 105 by osmometry and Mw/Mn < 1.10 by GPC) had narrow molecular weight distributions. A relationship between nonquantitative metallation and spacing of the graft points on a backbone molecule was discussed in detail. Two benzene‐cast films formed clear microphase‐separated structures of lamellar structure. The dependence of composition on the morphology of the block–graft copolymers was found to differ from that of common block copolymers. A degree of crystallinity of PEO segment and lamellar thickness of PEO phase serving as graft molecule were also found to differ from those of homo PEO and/or PEO segment in common block copolymer. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3021–3034, 1998

Ring-Opening Polymerization of Trimethylene Carbonate with Phosphazene Organocatalyst

“…A possible initiator/chain-end mechanism is proposed in Scheme 2 (see also other works on the anionic ROP of TMC through the initiator/chain-end mechanism). An alkoxy active center was generated by the hydrogen bond of t -BuP 4 with the initiator alcohol [ 40 , 41 , 42 ]. Then, alkoxy active center attacks the carbonyl of TMC subsequently with ring opening reaction to form the alkoxy active growth chain end.…”

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

“…were synthesized for the morphological study for the academic viewpoints. Furthermore, the functional polymeric materials from the multiblock copolymers have been also prepared for the industrial viewpoint, that is, preparation of charge-mosaic membrane from BABCB pentablock copolymers by Fujimoto et al [20][21][22][23][24] and fabrication of solid polymer electrolyte from block-graft copolymers by Hirahara et al [25][26][27][28][29][30][31] was one of the outstanding examples of the frontier works using living anionic polymerization technique.…”

Copolumers obtained by grafting of vinyl monomers on starch - influence of amines on synthesis and degradation processes in environment

“…PS se takoĎe moţe kalemiti i na poli(etilen-oksid) (PEO) [56]. Pored direktnog kalemljenja PEO na PS, PEO je kalemljen i na blok kopolimere, kao što je polistiren-blok-poli(hidroksistiren) [57]. Tehnikom disperzione polimerizacije dobijeni su kalemljeni kopolimeri PEO i PS, pri čemu se kao makromonomer koristio metakriloil-terminovani derivat poli(etilen-oksida) [58].…”