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

Abstract

The implementation of covalent adaptable networks (CANs) in general resin system is becoming attractive. In this work, we propose a simple post‐curing strategy based on the core‐shell structured acrylate latex for the achievement on both the improved general performance and the CANs characteristics in latex films. The building to the CANs was relied on the introduction of 4,4′‐diaminophenyl disulfide as the curing agent, which cured the acetoacetoxy decorated shell polymer through the ketoamine reaction. The metathesis reaction of aromatic disulfides in the crosslinking segments enabled the thermally induced dynamic behavior of the network as revealed in the stress relaxation tests by comparison with other diamine crosslinking agents without the incorporation of disulfide. The synergism of the dynamic crosslinking of the shell polymer and static crosslinking in the core polymer contributed to the improved mechanical strength (15 MPa, strain% = 250%) and the suppressed water adsorption (~1% in 24 h of soaking) of the latex film, which exhibited above 90% of recovery in both strength and strain from a cut‐off film damage within 1 h at 80°C. Moreover, the cured latex film could be recycled, and 75% of the mechanical performance was regained after three fragmentation‐hot‐pressing cycles. These, in addition with the feasible and environmental friendly characteristics, suggest a sustainable paradigm toward the smart thermosetting latex polymers.

The Post-Curing of Waterborne Polyurethane–Acrylate Composite Latex with the Dynamic Disulfide-Bearing Crosslinking Agent

“…Based on the Maxwell model for viscoelastic fluids, the τ was linearly fitted to the temperature based on the Arrhenius equation [40], and the results are shown in Figure 4c. The activation energy (E a ) was calculated through fitting, resulting in 31 kJ/mol, which value is much lower than that of all-PAC latex networks crosslinked by DTDA, as prepared by Gong et al [41]. The difference may stem from their low relative contents of AAEM/DTDA, which were limited to within 7%, accounting for the total weight of PAC.…”

Lignin-Based Covalent Adaptable Network Polymers─When Bio-Based Thermosets Meet Recyclable by Design

“…Classical thermosets describe a generic family of polymers including, for example, unsaturated polyesters, vinyl esters, epoxy, and polyurethane resins, typical representatives of CANs encompass epoxy-, polyester-, polyurethane-, polyacrylate- and phenolic-based resins. Among the most common monomer units used in CAN design are (i) bisphenol A diglycidyl ether (BADGE) and diglycidyl ether of bisphenol F (DGEBF), which are used to prepare epoxy-based CANs; (ii) diols and dicarboxylic acids, which are employed to produce polyester-based CANs; (iii) hexamethylene diisocyanate (HDI) and toluene diisocyanate (TDI) that are usually selected for the formation of polyurethane-based CANs; (iv) methyl methacrylate (MMA) and butyl acrylate (BA), which are commonly chosen to formulate acrylate-based CANs; and (v) phenol and formaldehyde are preferred to develop phenol-based CANs.…”

“…Classical thermosets describe a generic family of polymers including, for example, unsaturated polyesters, vinyl esters, epoxy, and polyurethane resins, 15 typical representatives of CANs encompass epoxy-, 16 polyester-, 17 polyurethane-, 18 polyacrylate- 19 and phenolic-based resins. Among the most common monomer units used in CAN design are (i) bisphenol A diglycidyl ether (BADGE) 20 and diglycidyl ether of bisphenol F (DGEBF), 21 which are used to prepare epoxy-based CANs;…”

The role of tertiary amines as internal catalysts for disulfide exchange in covalent adaptable networks

“…In addition, the E a value of CL–N was somewhat lower than the reported values (60–90 kJ mol −1 ) of elastomeric vitrimers prepared using side-group functionalized low T g polymers by the reaction with disulfide cross-linkers, again indicating catalytic effects of tertiary amines in the network. 70–72 To further support the importance of tertiary amines, we prepared another sample containing less fraction of tertiary amines by varying the initial feed mole ratio (see the characterization studies in Fig. S13–S15†).…”