Itaconic acid-based hyperbranched polymer toughened epoxy resins with rapid stress relaxation, superb solvent resistance and closed-loop recyclability

Abstract

The development of epoxy vitrimers with excellent overall properties and recyclability has been a great challenge.

Harnessing β-Hydroxyl Groups in Poly(β-Amino Esters) toward Robust and Fast Reprocessing Covalent Adaptable Networks

“…Compared to catalyst-free transesterification-based CANs reported so far, the PBAE-based CANs containing sufficiently large amounts of hydroxyl groups (e.g., BE 1 /BG 2 ) display one of the fastest stress-relaxation times because of the synergistic effects of transesterification and dynamic aza-Michael reaction (Figure c and Table S4). − ,,,− Note that the concentration of tertiary amines in our PBAE-based CANs is also relatively higher compared to other similarly designed CANs, , and this may also contribute to faster relaxation. Interestingly, the relaxation of BE 0 /BG 3 was slightly slower than that of BE 1 /BG 2 despite a larger number of hydroxyl groups, when their τ values were compared at 160 °C (Figure b).…”

High-Strength, Self-Healing, Recyclable, and Catalyst-Free Bio-Based Non-Isocyanate Polyurethane

“…Therefore, it is imperative to develop high-performance NIPUs. Introducing a hyperbranched structure can effectively improve the mechanical properties of polymers, , which can be attributed to the improved cross-linking density. − For example, the curing agents with hyperbranched structures have been proven to successfully enhance the mechanical strength of PUs. ,, Moreover, introducing rigid structures into polymers is another effective method to improve their mechanical properties. , …”

Synergistic catalytic effect of triple dynamic bonds for fast-reprocessing and high-performance cross-linked polymers

“…Recently, academics have made growing efforts to produce rapidly reprocessable DCPs. 8,16,[31][32][33][34] Tuning the network rearrangement efficiency of DCPs by adjusting the topological network structure is a facile and efficient method, and the preparation of DCPs with low cross-linked density and a high content of flexible segments can effectively improve the network rearrangement efficiency of DCPs, shorten the reprocessing time and even realize continuous reprocessing, 7,35,36 but it severely impairs the thermal and mechanical properties. In addition, accelerating exchange reactions of dynamic bonds via adding external catalysts, 32,37 upgrading dynamic bonds, 8,38,39 or adopting internal catalysis [40][41][42] is also an effective approach, but it causes difficulties in the design of DCPs.…”