Degradable and Recyclable Polyesters from Multiple Chain Length Bio‐ and Waste‐Sourceable Monomers

Abstract

Monomers sourced from waste or biomass are often mixtures of different chain lengths; e.g. catalytic oxidation of polyethylene waste yields mixtures of dicarboxylic acids (DCAs). Yet, polyesters synthesized from such monomer mixtures have rarely been studied. We report polyesters based on multiple linear aliphatic DCAs, present in chain length distributions that vary in their centers and ranges. We demonstrate that these materials can adopt high‐density polyethylene‐like solid state structures, and are ductile (e.g. Et 610 MPa), allowing for injection molding, or film and fiber extrusion. Melting and crystallization points of the polyesters show no odd‐even effects as dipoles cannot favorably align in the crystal, similar to traditional odd carbon numbered, long‐chain DCA polyesters. Biodegradation studies of 13C‐labelled polyesters in soil reveal rapid mineralization, and depolymerization by methanolysis indicates suitability for closed‐loop recycling.

Synthesis and Deconstruction of Polyethylene-type Materials

“…167 At the same time, ethylene glycol is available on a large scale and at lower cost than long-chain diols, and an increased density of ester bonds leads to further desirable properties, such as an increased environmental degradability (section 3.1). 165,167,174 The relationship between randomly placed ester, carbonate, and keto group density on polymer properties has been mapped out using hydrogenated model polymers from ADMET. This enables a convenient variation of the functional group density via the ratio of a functional group-containing and a pure hydrocarbon α,ω-diene comonomer (Figure 15a).…”

“…At the same time, ethylene glycol is available on a large scale and at lower cost than long-chain diols, and an increased density of ester bonds leads to further desirable properties, such as an increased environmental degradability (section ). ,, …”

“…Such polyesters from dicarboxylate mixtures are also of interest as the latter can be potentially sourced from low-value biomass or plastic waste (section 3.2.2). 174 For a combination of an (even-numbered) long-chain dicarboxylate, with the particularly short C 2 ethylene glycol, relatively high melting points are observed which may be due to the entire ethylene glycol monomer unit acting as single defect in the crystal (T m PE-2,18: 96 °C; T m PE-3,18: 82 °C; T m PE-4,18: 86 °C; T m PE-18,18: 99 °C). 167 At the same time, ethylene glycol is available on a large scale and at lower cost than long-chain diols, and an increased density of ester bonds leads to further desirable properties, such as an increased environmental degradability (section 3.1).…”

“…Notably, α,ω-dicarboxylic acids (DCAs) can be produced from HDPE by a variety of such oxidative processes (Figure 22). These products may serve as useful intermediates for consumer products, polymers, 174,247 or as biological feedstocks. 248,249 Oxidation of PE by hot fuming nitric acid was first developed as a means to isolate crystalline lamellae for the purpose of PE structural elucidation.…”

Aliphatic Polyester Materials from Renewable 2,3-Butanediol

“…Comparing the methyl branched PE-b4.X polyesters derived from 2,3-BD with linear PE-2.X polyesters from ethylene glycol (EG), 41 the 2,3-BD polyesters generally exhibit lower melting the melting temperatures of both types of polyesters approach each other, resulting in only minor differences between PE-b4.48 and PE-2.48, with values of 103 and 109 °C, respectively. A significant odd−even effect was found in the PE-2.X polyesters, which was absent in the PE-b4.X polyesters.…”