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Tailoring Rheological Properties of Thermoresponsive Hydrogels through Block Copolymer Adsorption to Cellulose Nanocrystals.

Biomacromolecules (2019-06-28)
Erwan Gicquel, Céline Martin, Quentin Gauthier, Joakim Engström, Clara Abbattista, Anna Carlmark, Emily D Cranston, Bruno Jean, Julien Bras
ABSTRACT

This study investigates the adsorption of a block copolymer composed of a poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) cationic polyelectrolyte and a poly(di(ethylene glycol) methyl ethermethacrylate) (PDEGMA) on oxidized cellulose nanocrystals (TO-CNCs) to produce hydrogels. PDMEAMA- b-PDEGMA was synthesized by atom-transfer radical polymerization. The extent and dynamics of the adsorption of PDMAEMA- b-PDEGMA on TO-CNCs were determined by electromechanical microbalance and optical techniques. Electrostatic adsorption was identified on TO-CNCs with the quaternized block copolymer. Small-angle neutron scattering experiments were performed to investigate the polymer behavior on the TO-CNC surfaces. Depending on the temperature, block copolymer induces the aggregation of nanocrystals after adsorption by connecting CNCs bundles with block copolymer chains. A reversible liquid-to-gel transition, triggered by temperature, was clearly detected by rheological measurements for the copolymer-CNC mixtures. At the optimal copolymer to CNC ratio the viscosity increased by 4 orders of magnitude at low shear rates. These stimuli-responsive CNC-based materials could be used as injectable biomedical systems.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Copper(II) chloride, 97%
Sigma-Aldrich
Copper(I) chloride, ReagentPlus®, purified, ≥99%
Sigma-Aldrich
1,1,4,7,10,10-Hexamethyltriethylenetetramine, 97%