Unexpected thermo-responsiveness of bisurea-functionalized hydrophilic polymers in water

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:581

Article

Mellot, Gaelle¹  Guigner, Jean-Michel²  Jestin, Jacques³  Bouteiller, Laurent¹  Stoffelbach, Francois¹  Rieger, Jutta¹ 

[1] Sorbonne Univ, Inst Parisien Chim Mol, Equipe Chim Polymeres, CNRS,UMR 8232, F-75252 Paris, France

[2] Sorbonne Univ, Inst Mineral Phys Mat & Cosmochim, UMR IRD MNHN 7590, CNRS, F-75005 Paris, France

[3] CEA Saclay, Lab Leon Brillouin, UMR CEA CNRS 12, Bat 563, F-91191 Gif Sur Yvette, France

关键词: Thermoresponsive;    LCST;    Supramacromolecular assemblies;    Cloud point nano-DSC;    Bisurea;    Cylindrical micelles;    Supramolecular bottlebrushes;    Hydrogen bonding;   

DOI  :  10.1016/j.jcis.2020.07.147

来源: Elsevier

【 摘 要 】

Hypothesis: Thermoresponsive polymers are important materials for various applications. However, the number of polymers that exhibit this property in the temperature range of interest remains limited. The development of novel rational design strategies through the understanding of the thermal transition's origin is therefore of utmost importance. Experiments: Bisurea-functionalized water-soluble polymers were synthesized by RAFT polymerization. After direct dissolution in water, the supramolecular assemblies were analyzed by cryo-TEM and SANS. Their temperature-dependent water-solubility was characterized by various techniques, namely DLS, SANS, DSC, IR, to understand the origin of the temperature sensitivity. Findings: The supramolecular assemblies exhibit an unexpected temperature-dependent solubility. For instance, a cloud point of only 39 degrees C was measured for poly(N,N-dimethylacrylamide) assemblies. This property is not restricted to one specific polymer but is rather a general feature of bisurea-functionalized polymers that form supramacromolecular bottlebrushes in water. The results highlight the existence of two distinct transitions; the first one is a visually perceptible cloud point due to the aggregation of individual micelles, presumably driven by the hydrophobic effect. The second transition is related to the dissociation of intermolecular bisurea hydrogen bonds. Finally, we show that it is possible to widely tune the cloud point temperature through the formation of co-assemblies. (C) 2020 Elsevier Inc. All rights reserved.

【 授权许可】

Free