Beyond the golden rule of polymer network dynamics: Design principles for tissue-mimetic viscoelasticity.

Technologies ranging from transportation to biomedical devices rely on soft materials whose performance hinges on balancing stiffness and damping. In conventional polymer networks, however, these properties are typically coupled: Softer materials are intrinsically more dissipative, reflecting a long-standing correlation in polymer dynamics that severely restricts the accessible design space. Here, we move beyond this longstanding constraint using brush-like polymer networks whose architecture in combination with chemistry governs viscoelastic response. By independently tuning strand volume and flexibility, we vary the elastic modulus over orders of magnitude while maintaining nearly constant relaxation time without altering network chemistry. Our findings establish a general framework for encoding viscoelastic responses in polymer networks, enabling the design of tissue-mimetic materials with programmable equilibrium stiffness and rate-dependent dissipation.