Terpenoid-Based High-Performance Polyester with Tacticity-Independent Crystallinity and Chemical Circularity.

The development of chemically circular, bio-based polymers is an urgently needed solution to combat the plastic waste crisis. However, the most prominent, commercially implemented bio-based aliphatic polyester, poly(lactic acid) (PLA), is brittle, therefore largely limiting its broad applications. Herein, we introduce a class of aliphatic polyesters produced through the ring-opening polymerization (ROP) of (1,5S)-8,8-dimethyl-3-oxabicyclo[3.

Chain-End Controlled Depolymerization Selectivity in α,α-Disubstituted Propionate PHAs with Dual Closed-Loop Recycling and Record-High Melting Temperature.

Within the large poly(3-hydroxyalkanoate) (PHA) family, C3 propionates are much less studied than C4 butyrates, with the exception of α,α-disubstituted propionate PHAs, particularly poly(3-hydroxy-2,2-dimethylpropionate), P3H(Me)P, due to its high melting temperature ( ∼ 230 °C) and crystallinity (∼76%). However, inefficient synthetic routes to its monomer 2,2-dimethylpropiolactone [(Me)PL] and extreme brittleness of P3H(Me)P largely hinder its broad applications. Here, we introduce simple, efficient step-growth polycondensation (SGP) of a hydroxyacid or methyl ester to afford P3H(Me)P with low to medium molar mass, which is then utilized to produce lactones through base-catalyzed depolymerization.

Metal-free initiators pave the way for chemically recyclable polymers with industrially relevant properties.

To solve the environmental disaster that is generated by legacy plastics accumulation, researchers are looking to design plastics with enhanced end-of-life options, but many circular plastics do not meet industrial requirements. Here, we highlight a metal-free approach to produce chemically recyclable poly(1,3-dioxolane) with ultra-high molecular weight and comparable properties to one of the most produced plastics, polyethylene.

Installing Controlled Stereo-Defects Yields Semicrystalline and Biodegradable Poly(3-Hydroxybutyrate) with High Toughness and Optical Clarity.

Stereo-defects present in stereo-regular polymers often diminish thermal and mechanical properties, and hence suppressing or eliminating them is a major aspirational goal for achieving polymers with optimal or enhanced properties. Here, we accomplish the opposite by introducing controlled stereo-defects to semicrystalline biodegradable poly(3-hydroxybutyrate) (P3HB), which offers an attractive biodegradable alternative to semicrystalline isotactic polypropylene but is brittle and opaque. We enhance the specific properties and mechanical performance of P3HB by drastically toughening it and also rendering it with the desired optical clarity while maintaining its biodegradability and crystallinity.

Modulating the Crystallinity of a Circular Plastic towards Packaging Material with Outstanding Barrier Properties.

Chemically recyclable polymers have attracted increasing attention since they are promising materials in a circular economy, but such polymers appropriate for packaging applications are scarce. Here a combined thermal, mechanical, and transport (permeability and sorption) study is presented of a circular polymer system based on biobased trans-hexahydrophthalide which, upon polymerization, can lead to amorphous, homochiral crystalline, and nanocrystalline stereocomplex materials. This study uncovers their largely different transport properties of the same polymer but with different stereochemical arrangements and synergistic or conflicting effects of crystallinity on transport properties versus thermal and mechanical properties.

Lactide-Valerolactone Copolymers for Packaging Applications.

Lactide-valerolactone copolymers have potential application in the packaging sector. Different copolymers were synthesized, and the kinetics of the copolymerization reactions and the microstructure of the copolymers were analysed. Lactide showed higher reactivity than valerolactone which leads to composition drift through the reaction.

Packaging materials with desired mechanical and barrier properties and full chemical recyclability.

Plastics have become indispensable in modern life and the material of choice in packaging applications, but they have also caused increasing plastic waste accumulation in oceans and landfills. Although there have been continuous efforts to develop biodegradable plastics, the mechanical and/or transport properties of these materials still need to be significantly improved to be suitable for replacing conventional plastic packaging materials. Here we report a class of biorenewable and degradable plastics, based on copolymers of γ-butyrolactone and its ring-fused derivative, with competitive permeability and elongation at break compared to commodity polymers and superior mechanical and transport properties to those of most promising biobased plastics.

Elaboration and Characterization of Conductive Polymer Nanocomposites with Potential Use as Electrically Driven Membranes.

In this work, a general, facile, and relatively low-cost method to produce electrically driven non-porous membranes by revalorization of recycled polyolefins is proposed. The polymer matrices are poly(propylene) (PP) and poly(ethylene) (PE) and their corresponding recycled samples, which are respectively mixed with carbon nanotubes (CNT). The performances of the elaborated nanocomposites are studied by morphological, rheological, and electrical conductivity tests.