3D Printable Modular Soft Elastomers from Physically Crosslinked Homogeneous Associative Polymers

We design and synthesize linear-associative-linear (LAL) triblock copolymers, where the associative middle block consists of amide groups that form double hydrogen bonds, while the linear end blocks aggregate into hard glassy domains that act as strong crosslinks. Importantly, the amide groups do not cluster into nanoscale structures, slowing down polymer dynamics without altering viscoelastic properties. This allows precise control over energy dissipation by adjusting the amide group fraction. Leveraging the self-assembly of block copolymer microstructures, we improve network stiffness with Young's moduli from 8 kPa to 8 MPa without significantly compromising a tensile-breaking strain of approximately 150%. To enable 3D printing of these LAL polymers, we use high-temperature Direct Ink Write (DIW) printing, a solvent-free melt processing technique that does not require post-treatment. Our LAL polymers combine homogeneous associative polymers with a high fraction of amide groups and block copolymer self-assembly, resulting in a dual-crosslinked network. This network provides a versatile platform for the modular design and development of soft, melt-reprocessable elastomeric materials with practical applications.