Nonlinear tribological behavior of polymeric microparticles under extreme collision conditions is required for an in-depth understanding of advanced applications in the fields of defense, biomedicine, and manufacturing. Laser-induced projectile impact tests with an incidence angle of 45° are conducted to investigate the tribological response at the contact interface of block copolymers with glassy–rubbery phases and a stationary substrate to induce deformations with an ultrahigh strain rate. Morphological-phase-dependent tribological and rheological responses are quantified from the mechanical interactions involving adiabatic heating, plastic flow, and interfacial shear instability. An effective coefficient of friction mechanism that depends on the rheological transition activated by impact velocity is proposed to specify the rheological response of the copolymers.

We designed and synthesized epoxy-encapsulated microparticles with core−shell structures via suspension polymerization to enable high-efficiency, room-temperature cold spray processing. The soft core of the microparticles was comprised of a thermoset resin, diglycidyl ether of bisphenol A (DGEBA), which was optionally blended with the thermoplastic, poly(butyl acrylate); the protective shell was formed using polyurea. The composition, morphology, and thermal behavior of the microparticles were investigated. An inverse relationship between deposition efficiency and particle size was demonstrated by varying the surfactant concentration that was used during particle synthesis. We also determined that the microparticles that had pure resin as the core had the lowest viscosity, exhibited a decrease in the critical impact velocity required for adhesion, had the best flowability, and yielded a dramatic increase in deposition efficiency (56%). We have demonstrated that our in-house synthesized particles can form homogeneous, smooth, and fully coalesced coatings using room-temperature cold spray.

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