Helical Crystals in Aliphatic Copolyesters: From Chiral Amplification to Mechanical Property Enhancement

Abstract

We demonstrate herein a bottom-up strategy for achieving helical crystals via chiral amplification in copolyesters by incorporating a small amount of (d)-isosorbide into semicrystalline polyester, poly(ethylene brassylate) (PEB). During bulk crystallization of poly(ethylene-co-isosorbide brassylate)s, the molecular chirality of isosorbide in the amorphous region is transferred to PEB crystal chirality and amplified by the formation of right-handed helical crystals. Increasing isosorbide content or reducing crystallization temperature leads to thinner PEB lamellae crystals, strengthening chiral amplification by forming superhelices with a smaller helical pitch. Moreover, the superhelices with smaller helical pitch (larger chiral amplification) endow aliphatic copolyesters with enhanced modulus, strength, and toughness without sacrificing elongation-at-break. The principle outlined here could apply to the design of strong and tough materials.

Effect of Coordination Sacrificial Bond Strength on Toughening Properties of Polyesters

“…In this work, we demonstrate a strategy to construct a toughening system where only the SBs are different. Polyesters with dangling TPY ligands were synthesized via a cascade polycondensation-coupling ring-opening polymerization (PROP) method, − and the SBs were introduced for toughening by the complexation of TPY with transition metal ions, as shown in Scheme . Since Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ are frequently used first-row transition metal ions that form coordination complex with TPY with different binding energy, the strength of metal–ligand coordination interactions was thus adjustable where Fe 2+ has the strongest while Zn 2+ has the weakest.…”

Chemical recycling of poly(butylene terephthalate) into value-added biodegradable poly(butylene adipate-co-terephthalate)

“…Recently, our group developed a cascade polycondensationcoupling ring-opening polymerization (PROP) method for the facile synthesis of copolyesters and their block copolymers, via the polymerization of diols with cyclic oligoesters. [43][44][45][46][47] Since the fast ROP process (<30 min) replaces the slow esterification process in typical CP (∼3 h), the polymerization speed of PROP is quite fast and can be finished within 3 h. The side reactions are suppressed and polymers without discoloration can be obtained, which is important for the film and bottle industry. In addition, the PROP process is very simple, just mixing the two monomers together and heating to the desired temperature under N 2 flow conditions or in a vacuum.…”

Chemical Recycling of Poly(butylene terephthalate) into Poly(ethylene brassylate-co-butylene terephthalate) with Tunable Thermal, Mechanical and Biodegradable Properties

“…Recently, our group has developed a novel cascade polycondensation coupling ring-opening polymerization (PROP) method for synthesizing an assortment of copolyesters and their multiblock copolymers, using aromatic/aliphatic cyclic esters as monomers and diols as initiators. − All of these reported copolyester systems commonly involved only one cyclic ester monomer, either aromatic or aliphatic cyclic esters. In this work, we tried to fabricate a kind of novel poly­(ethylene brassylate- co -butylene terephthalate) (PEBBT) copolyesters by dexterously combining chemical recycling of PBT and cascade PROP method (Scheme ).…”