Poly(carbonate acetal) vitrimers with enhanced thermal properties and closed-loop thermal recyclability derived from waste polycarbonate-derived polyaldehyde and pentaerythritol/erythritol/d-sorbitol
Journal
Green Chemistry
Journal Volume
26
Journal Issue
19
Start Page
10275
End Page
10289
ISSN
1463-9262
1463-9270
Date Issued
2024
Author(s)
DOI
10.1039/d4gc02934h
Abstract
We synthesized three poly(carbonate acetal) vitrimers (PCA-P, PCA-E, PCA-S) by condensing a waste polycarbonate-derived polyaldehyde (WPC-CHO) with pentaerythritol, erythritol, and d-sorbitol, using 0.5-4.0 mol% p-toluene sulfonic acid (pTSA) as a catalyst. Flexible PCA films emerged at pTSA concentrations ≥1 mol%, indicating a critical threshold of acid for effective condensation. The glass transition temperatures (Tg) of the films remained consistent across pTSA concentrations but varied based on the multi-alcohol structure, with Tg values of 178 °C for both PCA-P and PCA-S, and 142 °C for PCA-E, suggesting superior performance of pentaerythritol and d-sorbitol over erythritol as building blocks. Among these, the PCA-S series exhibited the best performance and utilized the least expensive starting materials, achieving the highest cost-performance index. The PCAs, featuring covalent adaptable polyacetal networks, facilitated thermal reprocessing through acetal metathesis. The second reprocessed PCA-P and PCA-S maintained similar thermal and mechanical properties to their original forms, demonstrating a closed-loop recycling. These polymers showed stability in THF/H2O (4/1) with 0.1-1.0 M H2SO4 at 25 °C, but can be degraded at 50 °C within 5 hours in both 0.5 M H2SO4 and HCl THF/H2O (4/1) solutions. NMR analysis of the degraded PCA-P confirmed the recovery of WPC-CHO and pentaerythritol. Furthermore, PCA-based carbon-fiber-reinforced plastics (CFRPs) were prepared, and the carbon fibers were successfully recovered after acid degradation without any loss to their structural or tensile integrity.
Publisher
Royal Society of Chemistry (RSC)
Type
journal article