Recyclable Polymethacrylate Networks Containing Dynamic Dialkylamino Disulfide Linkages and Exhibiting Full Property Recovery

Abstract

Reprocessable polymer networks with dynamic covalent bonds exhibit thermoplastic-like properties at elevated processing temperatures while maintaining thermoset responses under service conditions, offering a sustainable solution to the recycling of conventional, permanently cross-linked polymers. Most studies on reprocessable networks that report full cross-link density recovery after recycling have focused on step-growth polymer networks; no study has previously reported full cross-link density recovery of reprocessable networks prepared directly from only monomers via addition polymerization. Here, we report the utilization of dialkylamino disulfide chemistry as a fast, robust dynamic chemistry in the synthesis of reprocessable networks from monomers and/or polymers with carbon−carbon double bonds that are amenable to free-radical polymerization. In particular, we have employed a simple one-step method to design a bifunctional bis(dialkylamino) disulfide cross-linker. With this dynamic cross-linker, we synthesized a catalystfree, reprocessable polymethacrylate network that exhibits full property recovery (within error) associated with cross-link density after multiple reprocessing steps. This achievement could allow for the facile development of chemically recyclable versions of common, commercially important addition-type polymer networks.

Acrylate and Methacrylate Polymers’ Applications: Second Life with Inexpensive and Sustainable Recycling Approaches

“…This is considered the most suitable approach in terms of the simplification of recycling procedures, energy cost and the preparation of sustainable polymeric materials with a broad range of physico-chemical properties [ 134 ]. For example, recyclable catalyst-free polymethacrylate networks containing dynamic dialkylamino disulphide linkages (namely BiTEMPS) are synthesized by Bin Rusayyis et al [ 135 ]. The authors demonstrated that the reprocessable polymers with dynamic covalent bonds (both on step-growth polymer networks or based on full cross-link density recovery of reprocessable networks prepared from only monomers via addition polymerization) are characterized by thermoplastic-like properties.…”

Long-chain polyamide covalent adaptable networks based on renewable ethylene brassylate and disulfide exchange

“…Seeking for a simpler and more sustainable alternative towards longchain PA CANs, we focused on disulfides as an intrinsically reactive bond, 31,32 that can be activated under mild conditions. 33 Disulfides have been incorporated into urea, 34 urethane, 23,35,36 ester 4,37 and epoxy-based [38][39][40] networks, and have been combined with renewable building blocks such as diacids (succinic, adipic, sebacic), 4 castor oil 24,41 and epoxidized soybean oil, 42 leading to high-performance thermosets with impressive results regarding the ease of reprocessability and retainment of the mechanical properties after several reprocessing cycles.…”

Acyclic Diene Metathesis (ADMET) Polymerization of 2,2,6,6‐Tetramethylpiperidine‐1‐sulfanyl (TEMPS) Dimers

“…By virtue of their unique dissociation features, BiTEMPS were initially utilized as cross‐linking point within polymer networks to impart a thermally induced healing property. [ 15 ] Despite the elegant achievements based on the dynamic behavior of BiTEMPS derivatives, [ 16 ] such as the fusion of different cross‐linked polymers, [ 17 ] the topological rearrangement from linear to cyclic polymers, [ 18,19 ] and synthesis of end‐functionalized polymers, [ 20 ] to the best of our knowledge, the protocols utilized for the preparation of BiTEMPS containing polymers has been limited to conventional free‐radical or step‐growth polymerization approaches. Critically, due to the thermal lability of the BiTEMPS unit at temperatures above 80 °C, [ 14 ] previously reported polymerizations were essentially performed at ambient temperatures (Scheme 1B,C).…”