Biobased Reprocessable Polyhydroxyurethane Networks: Full Recovery of Crosslink Density with Three Concurrent Dynamic Chemistries

Abstract

Despite significant past efforts to exploit green, renewable precursors in polymeric materials and to improve the recyclability and reprocessability of nonisocyanate polyurethane (NIPU) networks, no single study has previously investigated biobased polyhydroxyurethane (PHU) network reprocessability. Renewable, dynamic PHU networks were synthesized by reacting bioderived polyfunctional cyclic carbonates, carbonated soybean oil (CSBO), and sorbitol ether carbonate (SEC), with either a synthetic diamine or a biobased diamine. Network reprocessability was studied by dynamic mechanical analysis. With relatively mild reprocessing conditions, CSBO-based PHU networks exhibit complete recovery of crosslink density and associated properties after multiple melt-state recycling steps. In addition to the presence of reversible cyclic carbonate aminolysis and transcarbamoylation exchange reactions, CSBO-based networks were shown via a model reaction to undergo a third dynamic chemistry based on a transesterification exchange reaction. In contrast to the excellent property recovery achieved by CSBO-based PHU networks, as a result of disadvantageous monomer molecular design, SEC-based networks exhibit poor reprocessability even with increased catalyst load and reprocessing temperature and time. This work reveals the effect of monomer structure on the reprocessability of dynamic polymer networks and highlights the effectiveness of CSBO to serve as a precursor of robust, sustainable NIPU networks with excellent reprocessability.

Recent progress in the catalytic transformation of carbon dioxide into biosourced organic carbonates

“…In some of these cases, despite the disappearance of epoxide and the appearance of IR-bands for the carbonate CvO stretching were observed, the actual chemoselectivity for the CC was not reported. 255,256 Mazo and Rios observed that the addition of water (about 33 mol%) significantly accelerates the carbonation of ESBO thus obtaining the corresponding CVO under atmospheric pressure with good conversion and selectivity in 70 h (entry 18). 257 This result is in line with the known ability of water to serve as a HBD in the cycloaddition of CO 2 to epoxides.…”

Renewable Castor‐Oil‐based Waterborne Polyurethane Networks: Simultaneously Showing High Strength, Self‐Healing, Processability and Tunable Multishape Memory

“…To date, most plant‐oil‐based PUs have exhibited poor thermal and mechanical properties and also required high temperature and long periods of time for self‐repair and reprocessing. In addition, PUs incorporating active dynamic bonds usually require a costly catalyst or high energy input to activate the exchange process, which may lead to catalyst instability and thermal degradation of the matrix [8a, 10] …”

Nanocomposites of Polyhydroxyurethane with POSS Microdomains: Synthesis via Non-Isocyanate Approach, Morphologies and Reprocessing Properties

“…In the past years, there has been ample literature to report the synthesis and correlation of structure with properties of PHUs [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. For instance, Endo et al [ 31 , 32 , 33 , 34 ] have reported the synthetic approaches of five- and six-membered cyclic carbonates, which can be used as the monomers of PHUs.…”