A simple copolymer with integrated high impact-stiffening, broadband damping, and active perception for advanced protection

Impact-stiffening materials with switchable stiffness are crucial for the development of next-generation intelligent protective systems. However, existing impact-stiffening materials often lack sufficient damping in the high-frequency (kHz) range, resulting in undissipated energy that may cause blunt trauma to protected tissues or organs. Herein, we report a thermodynamically guided strategy for constructing impact-stiffening materials with broadband frequency damping by tailoring the intermolecular interactions in polymers. As expected, the resulting polystyrene-co-poly(2-(2-ethoxyethoxy)ethyl acrylate) (PS-PDEEA) copolymer exhibits a high impact-stiffening response (1843 times, 0.1-100 Hz), broadband frequency damping (tan δ > 1.0, 10^-2-10³ Hz), and good optical transparency (transmittance > 80%). Moreover, by leveraging the charge-trapping properties of PDEEA, the copolymer is further designed as a triboelectric sensor, enabling the integration of impact protection with active perception.