Branched polymers by cationic ring‐opening polymerization

Abstract

Two methods for the synthesis of branched (co)polymers by cationic ring‐opening polymerization are presented. The first method is based on the spontaneous intermolecular termination that is observed in the polymerization of the four‐membered cyclic sulfides (thietanes). The branching points in these polymers are sulfonium ions. This method has been extended to polyether ‐ polysulfide block copolymers obtained by sequential polymerization of THF and a thietane. In the thus obtained AB block polymers, the branching points are concentrated in the sulfide segments only. By similar techniques, ABA types of block copolymer networks have been obtained making use of bifunctional initiators. The second method consists of copolymerizing a cyclic acetal such as 1,3‐dioxolane (DXL), with a “monofer”, which is a monomer that contains also a chain‐transfer function. As monofers for the DXL polymerization glycidol and glycerol formal were used. The end products are polyacetal‐polyols which contain a hydroxyl group at each of the chain ends. Reaction of these polyols with di‐isocyanates leads to the corresponding polyacetal polyurethanes.

Supramolecular Control of Propagation in Cationic Polymerization of Room Temperature Curable Epoxy Compositions

“…The further possibility to orient the mechanism path, observed in the presence of the highly chelating polyethers 18-crown-6, permits to envision the challenging possibility of inhibiting cationic ROP transfer reaction for instance in the case of the epoxy polymerization of so-called monofers, − i.e., molecules which are in the same time monomers and transfer agents and for which it is sometimes highly desirable to tailor the branching degree. − …”

Phase transition dynamics and mechanism for backbone-thermoresponsive hyperbranched polyethers

“…The cationic ring opening polymerization of glycidol as a latent AB 2 type monomer has been reported to lead to a water-soluble hyperbranched polyether. 20,[24][25][26] Given this, to construct a hydrophilic-hydrophobic balance in the hyperbranched backbones, THF was used as another monomer. Thus, random copolymerization of glycidol and THF was carried out through one-step cationic ring-opening copolymerization using BF 3 $OEt 2 as the initiator, and the synthesis route is shown in Scheme 1.…”

Aziridines and azetidines: building blocks for polyamines by anionic and cationic ring-opening polymerization

“…Indeed, upon a second addition of monomer, following complete consumption of the initial monomer concentration, molecular weight increased following the same rate as the initial polymerization, confirming this hypothesis. This contrasts from other heterocyclic CROP, such as oxetanes, 121 thietanes, 122 and selenetanes 123 in which the polymerizations either slowed or stopped at low conversions. This is attributed to the reaction of the heteroatoms in the polymer backbone to the growing chain end, producing unstrained, unreactive cations.…”