Highly Stretchable Polymers: Mechanical Properties Improvement by Balancing Intra‐ and Intermolecular Interactions

The mechanical properties of polymers are highly dependent on the mobility of the underlying chains. Changes in polymer architecture can affect inter‐ and intramolecular interactions, resulting in different chain dynamics. Herein, an enhancement in the mechanical properties of poly(butylmethacrylate) is induced by folding the polymer chains through covalent intramolecular crosslinking (CL). Intramolecular CL causes an increase in intramolecular interactions and inhibition of intermolecular interactions. In both the glassy and rubbery states, this molecular rearrangement increases material stiffness. In the glassy state, this molecular rearrangement also leads to reduced failure strain, but surprisingly, in the rubbery state, the large strain elasticity is actually increased. An intermediate intramolecular CL degree, where there is a balance between intra‐ and intermolecular interactions, shows optimal mechanical properties. Molecular dynamics simulations are used to confirm and provide molecular mechanisms to explain the experimental results. Balancing intra‐ and intermolecular interactions, intramolecular collapse enhances polymer stiffness and strength especially at an intermediate point where intra‐ and intermolecular interactions are balanced. In the rubbery state, highly stretchable thermoplastic plastics are obtained, reaching over 1400% strain at break. Molecular dynamics simulations support the experimental results and explain the effect of chain folding to bulk properties.