Peptide-reinforced amphiphilic polymer conetworks

Amphiphilic polymer conetworks (APCN) are polymer networks composed of hydrophilic and hydrophobic chain segments. Their applications range from soft contact lenses to membranes and biomaterials. APCNs based on polydimethylsiloxane (PDMS) and poly(2-hydroxyethyl acrylate) (PHEA) are flexible and elastic in the dry and the swollen state. However, they are not good at resisting deformation under load, i.e. their toughness is low. A bio-inspired approach to reinforce APCNs is presented based on the incorporation of poly(β-benzyl-aspartate) (PBLA) blocks between crosslinking points and PDMS chain segments. The mechanical properties of the resulting peptide-reinforced APCNs can be tailored by the secondary structure of the peptide chains (β-sheets or a mixture of α-helices and β-sheets). Compared to non-reinforced APCNs, the peptide-reinforced networks have higher extensibility (53 vs. up to 341%), strength (0.71 ± 0.16 vs. 22.28 ± 2.81 MPa) and toughness (0.10 ± 0.04 vs. up to 4.85 ± 1.32 MJ m-3), as measured in their dry state. The PBLA peptides reversibly toughen and reinforce the APCNs, while other key material properties of APCNs are retained, such as optical transparency and swellability in water and organic solvents. This paves the way for applications of APCNs that benefit from significantly increased mechanical properties.