Effect of the microstructure of n-butyl acrylate/N-isopropylacrylamide copolymers on their thermo-responsiveness, self-organization and gel properties in water

Fang Yin (1, 2) , Juliette Behra (1, 2) , Mariana Beija (1, 3) , Annie Brûlet (4) , Juliette Fitremann (1, 2) , Bruno Payre (5) , Stéphane Gineste (1, 2) , Mathias Destarac (1, 3) , Nancy Lauth de Viguerie (1, 2) , Jean-Daniel Marty (1, 2)

1 IMRCP - Interactions moléculaires et réactivité chimique et photochimique
2 IMRCP - IDeAS - IMRCP - Interfaces Dynamiques et Assemblages Stimulables
3 IMRCP - P3R - IMRCP - Polymères de Précision par Procédés Radicalaires
4 MMB - LLB - Matière molle et biophysique
5 CMEAB - Centre de Microscopie Électronique Appliquée à la Biologie

Abstract Hypothesis Polymer composition, microstructure, molar mass, architecture… critically affect the properties of thermoresponsive polymers in aqueous media. Experiments The behaviour of n-isopropylacrylamide and n-butyl acrylate-based copolymers of variable composition and structure (statistical, diblock or triblock) was studied in solution at different temperatures and concentrations with turbidimetry measurements, differential scanning calorimetry, electronic microscopy, rheology and scattering experiments. Findings This study illustrates how it is possible through chemical engineering of the microstructure of amphiphilic thermoresponsive polymers to modulate significantly the self-assembly, morphological and mechanical properties of these materials in aqueous media. Statistical structures induced a strong decrease of cloud point temperature compared to block structures with similar composition. Moreover, block structures lead below the transition temperature to the formation of colloidal structures. Above the transition temperature, the formation of colloidal aggregates is observed at low concentrations, and at higher concentrations the formation of gels. Neutron scattering and light scattering measurements show that for a given composition diblock structures lead to smaller colloids and mesoglobules than their triblock counterparts. Moreover, diblock structures, compared to triblock analogs, allow the formation of gels that do not demix with time (no synaeresis) but that are softer than triblock gels. Graphical abstract The microstructural engineering of amphiphilic thermoresponsive copolymers of n-butyl acrylate and N-isopropylacrylamide allows significant modulations of the self-assembly, morphological and mechanical properties of these materials in aqueous media.

Domaines: Chimie

Fang Yin, Juliette Behra, Mariana Beija, Annie Brûlet, Juliette Fitremann, et al.. Effect of the microstructure of n-butyl acrylate/N-isopropylacrylamide copolymers on their thermo-responsiveness, self-organization and gel properties in water. Journal of Colloid and Interface Science, 2020, 578, pp.685-697. ⟨10.1016/j.jcis.2020.06.005⟩. ⟨hal-02873611⟩