Unexpected Chiro-Thermoresponsive Behavior of Helical Poly(phenylacetylene)s Bearing Elastin-Based Side Chains

The thermoresponsive behavior of an elastin-based polymer can be altered by the polymeric macromolecular conformation. Thus, when the elastin basic amino acid sequence VPGVG is used as a pendant group of a poly(phenylacetylene) (PPA) its thermoresponsive behavior in water can be remotely detected through conformational changes on the formed helix. Circular dichroism at different temperatures shows an inversion of the first Cotton effect (450 nm) at 25.8 °C that matches with the cloud point temperature. The elastin-based side-chain poly(phenylacetylene) shows an upper critical solution temperature with low pH and concentration dependency, not expected in elastin-based polymers. It was found that the polymer self-assembles in water into spherical nanoparticles with hydrodynamic diameters of 140 nm at the hydrophobic state.Fundación Segundo Gil Dávila Dahlem Research School, Freie Universität Berlin. Grant Number: Dahlem International PostDocs fellowship Ministerio de Ciencia e Innovación. Grant Number: CTQ2015-70519-P Xunta de Galicia. Grant Number: Centro Singular de Investigación de Galicia Acreditación 2016-2019 European Regional Development Fund. Grant Number: ERDF Bundesministerium für Bildung und Forschung. Grant Number: Nanomatfutur award, 13N12561, ThermonanogeleS