Biological materials, such as proteins and peptides, use different strategies (e.g. hierarchical structures, self-assembly, hydrophobic and hydrophilic interactions and hydrogen bonding) due to secondary structures to enhance both strength and toughness, which are generally mutually exclusive. Drawing on nature we have prepared bioinspired amphiphilic polymer conetworks (APCNs) based on α,ω-dimethacrylate-functionalized poly(β-benzyl-aspartate)-block-poly-(dimethylsiloxane)-block-poly(β-benzyl-aspartate) (PBLAx-b-PDMS-b-PBLAx) triblock copolymers as hydrophobic phase. Amphiphilic polymer conetworks (APCNs) contain a hydrophilic and a hydrophobic phase separated in the nanoscale. Such silicone-based APCNs are elastic, transparent and swell in water and organic solvents. They are a class of materials with potential applications as soft contact lenses, catalyst support, sensors, and biomaterials. Bioinspired peptide-polymer hybrids attempt to combine the structural hierarchy that is often found in natural materials with synthetic macromolecules, e.g. by having soft and hard segments, to enhance the properties of the material. We have developed APCNs that combine strength and toughness using triblock copolymers that contain a varying number (5 and 20) of repeating peptide units. These peptide-functionalized APCNs exhibit higher extensibility (up to 450%) and increased toughness (up to 8 MJ/m3) compared to conventional, control APCNs (extensibility ~ 60 %, toughness ~0.14 MJ/m3). The swelling behavior of these APCNs changes in a unique and interesting way depending on how many peptidic (PBLAx) repeating units incorporated within the hydrophobic phase. We have characterized the microstructure of the materials using atomic force microscopy (AFM), solid state nuclear magnetic resonance (NMR), and small-angle X-ray scattering (SAXS) to understand how differences in architecture driven by peptide assembly (i.e. β-sheet and α-helix secondary structure and hydrogen bonding) impact mechanical response.

Characterizing the effect of poly(β-benzyl-aspartate) peptide on the mechanical properties of bioinspired amphiphilic polymer conetworks

ACS Spring Meeting 2021

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