Elevation of mechanically robust and reprocessable thermoset polyurea composites towards permanent shape reconfiguration controlled by heat and electricity

Oxime–Urethane Structure‐Based Dynamically Crosslinked Polyurethane with Robust Reprocessing Properties

“…The solvent resistance experiments were conducted according to the previously reported method. [30][31][32] As depicted in Figure 3, the swelling test shows that all the samples of DOPUs are not dissolved and only slightly swollen in DMF. The results further confirm the presence of stable cross-linked structures in DOPUs.…”

Solving the difficult recyclability of conventional thermosetting polyurea elastomers based on commercial raw materials in a facile way

“…DMA was utilized to characterize stress relaxation in a stress relaxation mode at a setting strain of 10% and to measure the creep and recovery experiments and in a creep mode held at 0.05 MPa stress for 10 min, where stress was removed for 10 min from 150 to 180 C. Solvent resistance experiments were conducted by soaking the sample in a solvent, which was replaced by a new solvent every day. 12 Gel contents were obtained by the Soxhlet extraction experiment in THF at 90 C. 20 The solvent uptake experiment was measured via soaking the sample of TPUEs in DMF, which was replaced by fresh DMF every day until the samples were fully swollen. Aer that, the swollen samples were removed from DMF and weighed aer removing the excess DMF on a lter paper.…”

“…Therefore, our group used a commercial raw material, 2,6-dimethyl piperazine, to devise dynamic thermosetting polyureas, whose composites can simultaneously have exceptional mechanical properties, such as reprocessability and permanent shape reconguration controllable by heat and electricity, as well as perform multiple functions. 12,13 Additionally, Xu's group presented a dynamic covalent polyurea type via a highly efficient polyaddition reaction of pyrazoles and diisocyanates; the poly(pyrazole-ureas) (PPzUs) had excellent mechanical properties and recyclability based on the reversibility of pyrazole-urea bonds. 14 Although the aforementioned studies have developed dynamic polyureas by integrating HUBs into the molecular structure of traditional, multifunctional thermosetting polyureas, 15 achieving chemical stability of HUBs is still a challenge, which may cause hydrolysis of isocyanate groups due to moisture under mild conditions.…”

Intrinsic toughened conductive thermosetting epoxy resins: utilizing dynamic bond and electrical conductivity to access electric and thermal dual-driven shape memory

“…This phenomenon can be attribute to the reason that the solvent could only be absorbed in the crosslinked network, resulting in swelling, but it could not dissolve the sample because of the crosslinked structure. 44 In Fig. 2c, the swelling radio of EPU1 in different solvents is exhibited in a bar chart.…”