Effect of bulky 2,6-bis(spirocyclohexyl)-substituted piperidine rings in bis(hindered amino)trisulfide on thermal healability of polymethacrylate networks

Abstract

This paper describes the synthesis of highly sterically hindered piperidinyl trisulfide with four spirocyclohexyl moieties, bis(2,6-bis[spirocyclohexyl]piperidine-1-yl)trisulfide (BIBSCPS-S3), from commercially available starting materials in short steps and its application as a...

Simple upcycling of virgin and waste polyethylene into covalent adaptable networks: catalyst-free, radical-based reactive processing with dialkylamino disulfide bonds

“…Polysulde derivatives of BiTEMPScontaining molecules and the dynamic polymer networks synthesized with them have been shown previously to have similar dynamic character to BiTEMPS-containing molecules and their dynamic covalent polymer networks with disulde bridges. 62,64 As we demonstrate further, any polysulde presence in BiTEMPS methacrylate has negligible effect on the thermomechanical properties and reprocessability of PE CANs.…”

“…We note that the formation of poly-sulde analogues of BiTEMPS methacrylate is possible given other syntheses involving the reaction of tetramethylpiperidine derivatives and S 2 Cl 2 (and in other syntheses involving the use of S 2 Cl 2 ). 62,64,80,[91][92][93][94][95][96] S 2 Cl 2 reacts with water to produce elemental sulfur which dissolves in and reacts with S 2 Cl 2 to give organic polysulfanes with the formula S n Cl 2 (n > 2). 97 Polysulfanes present in S 2 Cl 2 will predispose the synthesis of BiTEMPS methacrylate (and other desired compounds) to forming higher order polysuldes as major and minor products.…”

“…These include step-growth reactions between polymers made by free-radical polymerization (FRP) and small-molecule additives serving as cross-linkers. 60,61 Preparing dynamic networks with robust properties by exclusively addition-type polymerization methods, e.g., FRP and its variants 32,42,43,[48][49][50][51][52][62][63][64] or radicalbased reactive processing, [65][66][67][68][69][70][71][72][73][74][75][76][77][78][79] is a relatively untapped approach in CAN technology. It is important that methods to develop CANs via FRP and radical-based reactive processing are investigated because many thermosets with limited recyclability, e.g., PEX, are synthesized by such methods.…”

“…82 Otsuka and co-workers later demonstrated the utility of BiTEMPS-containing molecules with a trisulde bridge (dialkylamino trisulde) as dynamic cross-linkers in the synthesis of polymethacrylate CANs. 62,64 Dialkylamino trisul-des dissociate asymmetrically upon heating into stable thiyl and dithiyl radicals. 62 Compared to the disulde bond in BiTEMPS, the S-S bonds in dialkylamino trisuldes were found to have nearly identical bond dissociation energies (BDEs, 108.4 kJ mol −1 for trisulde vs. 109.6 kJ mol −1 for disulde) and a slightly larger propensity for chain transfer due to a reduction in steric hindrance.…”

“…60,61 Preparing dynamic networks with robust properties by exclusively addition-type polymerization methods, e.g. , FRP and its variants 32,42,43,48–52,62–64 or radical-based reactive processing, 65–79 is a relatively untapped approach in CAN technology. It is important that methods to develop CANs via FRP and radical-based reactive processing are investigated because many thermosets with limited recyclability, e.g.…”