Anionic polyelectrolytes with various charge densities and a well-defined chain architecture have great industrial and fundamental importance. In this article, we describe the synthesis and characterization of new sterically crowded conformationally constrained anionic polyelectrolytes with tunable charge densities based on highly functionalized stilbene-maleic anhydride/maleimide comonomers. Polyelectrolyte precursors with tert-butyl carboxylate protecting groups are first prepared by radical polymerization and readily characterized by 1 H NMR, SEC, TGA, and DSC without the complications normally arising with charged macromolecules. The precursors are converted into their corresponding deblocked forms by simply reacting with trifluoroacetic acid to deprotect the tert-butyl group and then neutralized in basic aqueous solutions to yield anionic polyelectrolytes.
Nature has achieved controlled and tunable mechanics via hierarchical organization driven by physical and covalent interactions. Polymer-peptide hybrids have been designed to mimic natural materials utilizing these architectural strategies, obtaining diverse mechanical properties, stimuli responsiveness, and bioactivity. Here, utilizing a molecular design pathway, peptide-polyurea hybrid networks were synthesized to investigate the role of architecture and structural interplay on peptide hydrogen bonding, assembly, and mechanics. Networks formed from poly(β-benzyl-l-aspartate)-poly(dimethylsiloxane) copolymers covalently cross-linked with a triisocyanate yielded polyurea films with a globular-like morphology and parallel β-sheet secondary structures. The geometrical constraints imposed by the network led to an increase in peptide loading and ∼7x increase in Young's modulus while maintaining extensibility (∼160%). Thus, the interplay of physical and chemical bonds allowed for the modulation of resulting mechanical properties. This investigation provides a framework for the utilization of structural interplay and mechanical tuning in polymer-peptide hybrids, which offers a pathway for the design of future hybrid biomaterial systems.
Nature has achieved diverse functionality via hierarchical organization driven by physical interactions such as hydrogen bonding. Synthetically, polymer-peptide hybrids have been utilized to achieve these architectural arrangements and obtain diverse mechanical properties, stimuli responsiveness, and bioactivity. Here, we explore the impact of peptide ordering and soft/hard phase interactions in PEG-based non-chain extended and chain extended peptidic polyurea (PU) and polyurea/polyurethane (PUU) hybrids towards tunable mechanics. Increasing the peptide content of poly(ε-carbobenzyloxy-l-lysine) (PZLY) revealed an increase in α-helical formation and modulation in amine/ether hydrogen bonding, suggesting enhanced intermolecular hydrogen bonding between peptide segments and soft/hard blocks. A balance of phase mixing and microphase segregation was observed depending on competitive hydrogen bonding and the hybrid architecture. This phase behaviour strongly modulated the mechanical response, particularly modulus and extensibility. We anticipate that this solid-state, synthetic framework will expand the reach of our peptide hybrids into biointerfacing materials, including scaffolds and responsive actuators via peptide selection.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.