Thermosensitive Cellulosic Biohybrid Comb Copolymers by the Passerini-3CR: 2-Fold Functionalization and Subsequent Thermal Response.

This work showcases the synthesis of unprecedented thermosensitive biohybrid carboxymethyl cellulose (CMC)-based comb copolymers by a Passerini three-component reaction (P-3CR) in aqueous conditions. CMC was concomitantly functionalized by various hydrophobic aldehydes and a set of isocyanide-terminated poly(ethylene oxide--propylene oxide) (P(EO--PO)) segments, exhibiting a lower critical solution temperature (LCST) in water. The P-3CR allowed us to design a library of copolymers differing in their structural compositions (degrees of substitution up to 0.35). The graft copolymers exhibit a thermoinduced sol-gel transition in water due to the reversible formation of hydrophobic domains between dehydrated polyether segments that behave as stickers. From the structure-function relationship, the pivotal result lies in the possibility to tune the thermal response of the biohybrids by the structure of the grafted aldehyde, whose hydrophobicity strongly promotes the thermoassociation process. Thus, the P-3CR paves the way for targeting thermoresponsiveness that can be cleverly adjusted to specific end-uses, which is highly desired for biological applications.