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Thiol‐isocyanate chemistry, combined with a dual capsule strategy, is used for the development of extrinsic self‐healing epoxy materials. It is shown that the amine groups present in the matrix both serve as a catalyst for the addition reaction between a thiol and an isocyanate and as a way to covalently link the healed network structure to the surrounding resin. The tapered double cantilever beam (TDCB) geometry is used for evaluating the recovery of the fracture toughness at room temperature after different healing times. Using manual injection of the healing agents into the crack, a healing efficiency up to 130% is obtained for the EPIKOTE 828/DETA epoxy material. On the other hand, when two types of microcapsules, one containing a tetrathiol reagent and the other a low toxic isocyanate reagent, are incorporated into this epoxy thermoset (20 wt%), a recovery of more than 50% is reached. The influence of parameters such as the amount and core content of the microcapsules on the healing efficiency is investigated. Furthermore, the thiol‐isocyanate chemistry is also tested for an industrial cold‐curing epoxy resin (RIM 135/RIMH 137).

Recently we reported the critical content threshold of epoxidized polybutadiene (PBep) units to induce total miscibility between poly(styrene-b-butadiene) (SB) block copolymers (BC) and uncured epoxy resin. In this work we investigate the different mechanisms involved through morphology development, depending on the content of epoxidized polybutadiene (PBep) in the initial mixture. PBep contents higher than, close below, or far below the critical threshold lead to long-range order nanostructures through reaction-induced microphase separation (RIMS) of PS block, a combination of both self-assembly and RIMS leading to vesicles or long wormlike micelles with a bilayered structure, or macroscopic phase separation, respectively. Nanoindentation was employed to identify the microphase-separated domains. Epoxy matrix can be significantly toughened for high BC contents in both prior to or through curing microphase-separated mixtures. Phase-separated domain size but also extent of interactions between them and their shape seem to be the factors contributing to toughness enhancement.

Spider silk is an icon of supertough energy absorbing polymeric material which its macromolecular multiblock composition has been attributed to be responsible for such remarkable properties. As in spider silk, polyurethanes can be synthesized with two distinct block which can differ in nature, combining properties like deformability and relatively high strengths. Here we synthesized and studied four different block polyurethanes with two different soft segments (SS) and two different hard segments (HS), with the aim of discovering the best molecular architecture to develop best mechanical performance after macromolecular alignment. The difference between soft segments is the crystalline nature, one in the rubbery state (T g, SS < T room ) and the other in the semicrystalline state at room temperature (T room < T m, SS ). In parallel one hard segment was amorphous in the glassy state (T room < T g, HS ) and the other semicrystalline (T g, HS < T room < T m, HS ). Results indicate that polyurethane with crystalline soft segments produce stronger materials after drawing than polyurethanes with rubbery soft segments, but the most exciting finding is the influence that hard segment has on the mechanical performance of predrawn materials, having polyurethanes prepared with semicrystalline hard segments more capability to undergo macromolecular alignment than materials with glassy segments, developing stiffer, stronger, and tougher materials.