Polythiourethanes Crosslinked with Dynamic Disulfide Bonds: Synthesis via Nonisocyanate Approach, Thermomechanical and Reprocessing Properties

Abstract

Polythiourethanes (PTUs) crosslinked with dynamic disulfide bonds are synthesized via a nonisocyanate approach. First, a difunctional five‐membered cyclic trithiocarbonate (1) is synthesized via the reaction of diglycidyl ether of bisphenol A (DGEBA) with carbon disulfide (CS2). Thereafter, the step‐growth polymerizations of 1 with α,ω‐diamino poly(propylene oxide)s with various molar masses are carried out to obtain a series of linear poly(mercapto thiourethane)s. These linear poly(mercapto thiourethane)s are readily crosslinked upon formation of disulfide bonds, which are generated via radical coupling reaction with the side mercapto groups. These crosslinked PTUs can be tailored into the materials from thermosetting plastics to crosslinked elastomers, depending on the molar masses of α,ω‐diamino poly(propylene oxide)s. More importantly, these crosslinked PTUs display excellent reprocessing properties at elevated temperatures, which is attributable to the metathesis reaction of dynamic disulfide bonds.

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

“…Trifunctional polyetheramine under the trade name of Jeffamine-T403 was purchased from Sigma Co, Shanghai China and it had a quoted molecular weight of M n = 443 Da. Diglycidyl ether of bisphenol A (DGEBA)-based five-membered cyclic carbonate (denoted DE5CC) was synthesized following the approach of literature [ 53 ]. Organic solvents such as tetrahydrofuran (THF), methanol, toluene, and dichloromethane were supplied from Admas, Co., Shanghai, China.…”

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

“…4b. The acti-vation energy (E a ) was calculated to be 76.7 kJ mol −1 , a value comparable to some other disulfide-based CANs, 23,36,39,71 although it can vary significantly both for the aliphatic and aromatic disulfide exchange reaction. 4,24,40 The dynamic character was further proven for all the PA CANs with different content of Cys, and the EDOBA50 control network was tested under the same conditions.…”

“…At 105°C τ was 1.06 s indicating an extremely rapid relaxation and a very easy activation of the disulfide exchange reaction, similar to other disulfide-based CANs containing flexible polysulfide or polyether segments. 71,72 In fact, the very fast relaxation is likely ascribed to the highest M c of Cys60 (6320 g mol −1 ) as the long flexible amide strands are expected to enable longer-range chain mobility compared to the other more densely crosslinked PA CANs. Hence, the exchange between disulfides is promoted as the probability of two adjacent groups meeting is increased.…”

A post curing strategy toward the feasible covalent adaptable networks in polyacrylate latex films

“…The characteristics of the dynamic and stimulus responsive CANs enable the polymer to be repaired, recycled, and reprocessed after it has been cured, while the high performance can also be assured including mechanical properties, environmental resistances, and dimensional stability under service conditions 3–5 . Extensive researches have been conducted, and series of dynamic chemical reactions have been involved in the construction of CANs, which can be divided as the dissociative reactions such as the boronate ester and Diels–Alder reaction, 6–9 the associative reactions such as transamination of vinylogous urethanes, 10,11 silyl ether transalkoxylation 12 and hydroxyurethanes, 13 and those possibly with multiple bond exchange mechanisms such as the metathesis of aromatic disulfide 14,15 …”