Mapping Structure and Rheology of pH-Responsive Resins for Low-VOC Coatings.

In recent years, the paint and coatings industry has shifted away from traditional resin formulations that require high concentrations of volatile organic compounds (VOCs) to achieve the desired rheological performance and sustainability targets. One approach to eliminate or reduce VOCs in paint and coating formulations while maintaining the final performance is to disperse stimuli-responsive polymer latex particles in water. The chemistry and architecture of these particles have been engineered such that the suspension rheology changes in response to the pH changes.

Secondary-Structure-Mediated Hierarchy and Mechanics in Polyurea-Peptide Hybrids.

Peptide-polymer hybrids combine the hierarchy of biological species with synthetic concepts to achieve control over molecular design and material properties. By further incorporating covalent cross-links, the enhancement of molecular complexity is achieved, allowing for both a physical and covalent network. In this work, the structure and function of poly(ethylene glycol) (PEG)-network hybrids are tuned by varying peptide block length and overall peptide content.

Synthetic approach to tailored physical associations in peptide-polyurea/polyurethane hybrids.

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.

Molecular Design: Network Architecture and Its Impact on the Organization and Mechanics of Peptide-Polyurea Hybrids.

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.

Tunable Mechanics in Electrospun Composites via Hierarchical Organization.

Design strategies from nature provide vital clues for the development of synthetic materials with tunable mechanical properties. Employing the concept of hierarchy and controlled percolation, a new class of polymer nanocomposites containing a montmorillonite (MMT)-reinforced electrospun poly(vinyl alcohol) (PVA) filler embedded within a polymeric matrix of either poly(vinyl acetate) (PVAc) or ethylene oxide-epichlorohydrin copolymer (EO-EPI) were developed to achieve a tunable mechanical response upon exposure to specific stimuli. Mechanical response and switching times upon hydration were shown to be dependent on the weight-fraction of MMT in the PVA electrospun fibers and type of composite matrix.

Anti-HIV activities of precisely defined, semirigid, carboxylated alternating copolymers.

Di-tert-butyl (E)-4,4'-stilbenedicarboxylate and tert-butyl 4-vinylbenzoate were copolymerized with maleic anhydride and tert-butyl 4-maleimidobenzoate, individually and respectively. After conversion into polyanions, these four copolymers exhibited activity against four HIV-1 strains: IIIb, BaL, JR-CSF, and 92UG037. For both the IIIb and BaL HIV-1 strains, the lowest IC50 (0.

Sterically Crowded Anionic Polyelectrolytes with Tunable Charge Densities Based on Stilbene-Containing Copolymers.

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 -butyl carboxylate protecting groups are first prepared by radical polymerization and readily characterized by H NMR, SEC, TGA, and DSC without the complications normally arising with charged macromolecules.