Properties of polyrotaxane modified maleimide resin with a phase‐separated structure

Abstract Polyrotaxane (PR) is a supramolecular polymer in which an axial polymer extends through multiple cyclic molecules. Specifically, PR comprises polyethylene glycol, α‐cyclodextrin and adamantane as the axial polymer, cyclic molecule and terminal blocking group, respectively. PR is a useful stress relaxation material because the cyclic polymers can freely slide and rotate in cyclic motions on the axial polymer. In this study, 4,4′‐diphenylmethane bismaleimide (BMI)/2,2′‐diallylbisphenol A (DABPA) resin was blended with PR as a toughness modifier; the effect of PR on the cured properties of BMI/DABPA resin is reported and the properties are related to the phase structure of BMI/DABPA/PR alloy. The BMI/DABPA/PR alloy formed a microphase‐separated structure with PR particles dispersed in the BMI/DABPA resin matrix. Increasing PR concentration greatly improved the toughness, impact resistance and adhesiveness of the resin. The glass transition temperature also increased because the numerous hydroxyl groups of α‐cyclodextrins in PR formed intermolecular hydrogen bonds in the BMI/DABPA resin, forming a dense network structure. In contrast, owing to the small concentration ratio of PR to BMI/DABPA resin, the dielectric constant, dielectric loss tangent and water absorption were only slightly higher than those of the unmodified resin. © 2022 Society of Industrial Chemistry.