Janus Polymerization: A One‐Shot Approach towards Amphiphilic Multiblock Poly(ester‐acetal)s Directly from 1,3‐Dioxolane with ε‐Caprolactone

Abstract

Janus polymerization consists of anionic and cationic ring opening polymerizations (AROP and CROP) at the two ends of a single propagating polymer chain, followed by a self-triggered chain extension generating multiblock copolymers (MBCPs) in one step. In the contribution, Janus polymerization by Tm(OTf) 3 or Er(OTf) 3 catalyst with an epoxy initiator is applied to synthesize MBCPs of semi-crystalline poly(ε-caprolactone) (PCL) blocks from coordinated AROP and poly(1,3-dioxolane-co-ε-caprolactone) (P(DO-co-CL)) blocks from CROP of DO with CL. Meanwhile, amorphous random copolymers [P(DO-r-CL)] are synthesized as control by employing other rare earth triflates [RE(OTf) 3 , RE = Y, Nd, Gd and Lu] as catalysts or in the absence of an initiator via CROP. On account of the distinguishable chemical structures and thermal properties between Janus MBCPs and cationic random copolymers, Janus features are confirmed including the CROP and AROP at a single propagating chain. The resultant amphiphilic copolymers self-assemble to nanoparticles in aqueous solution with designable diameters with the corresponding ratios of hydrophilic and hydrophobic segments. MBCPs exhibit good shape memory properties with appropriate deformation temperature close to human body's, providing a prospect on the applications in biomedical devices.

Poly(ester-co-ether) from ring-opening copolymerisation of sustainable 2-methyltetrahydrofuran with β-butyrolactone

“…As Lewis acids, rare-earth triflates (RE(OTf ) 3 ) are highly active catalysts for cationic ROP of lactones and cyclic ethers. 26,[28][29][30][31][32][33][34][35] From this point of view, it is possible to synthesize novel 2-MeTHF-based polymeric materials through the cationic ring-opening copolymerization of 2-MeTHF with BBL catalysed by (RE(OTf ) 3 ).…”

Recent Advances in Sequence‐Controlled Ring‐Opening Copolymerizations of Monomer Mixtures

“…[144] The copolymerization of ɛ-CL and 1,3-dioxolane was recently achieved by Tm(OTf) 3 -mediated ROP to produce PCL-b-P(DO-co-CL). [145] (Scheme 7d)…”

“…The cationic copolymerization of LA and cyclic acetal (1,3‐dioxolane, DO) was achieved by dropwise adding 1,3‐dioxolane after the triflic acid‐mediated ROP of LA started, which afforded poly(ester‐ co ‐acetals) having final acetal contents ranging from 7–27%, and M n s from 7–14 kDa (Scheme 7c) [144] . The copolymerization of ϵ‐CL and 1,3‐dioxolane was recently achieved by Tm(OTf) 3 ‐mediated ROP to produce PCL‐ b ‐P(DO‐ co ‐CL) [145] . (Scheme 7d)…”

Ring‐Opening Polymerization of Cyclic Acetals: Strategy for both Recyclable and Degradable Materials

“…For example, Janus polymerization of DO with CL using the initiating/catalytic system of RE(OTf) 3 /propylene oxide (RE = Tm or Er) yielded poly[PCL‐ alt ‐poly(CL‐ co ‐DO)] multiblock copolymers, where PCL block was formed by the coordinated anionic ROP (AROP) and poly(CL‐ co ‐DO) block by CROP of DO with CL ( Scheme ). [ 81 ] The CL content in poly(CL‐ co ‐DO) block was so low that both PCL and poly(CL‐ co ‐DO) blocks were crystallizable. That is, the resulting poly[PCL‐ alt ‐poly(CL‐ co ‐DO)] exhibited two distinguishable melting points, which afforded it shape memory property.…”