Issue 9, 2017

Intra-molecular interactions dominating the dehydration of a poly(2-isopropyl-2-oxazoline)-based densely grafted polymer comb in aqueous solution and hysteretic liquid–liquid phase separation

Abstract

Temperature-induced phase transition together with the liquid–liquid phase separation (LLPS) phenomenon of poly(oligo(2-isopropyl-2-oxazoline)methacrylate) with the comb-shaped architecture (comb-PiPOx) in aqueous solution has been discussed at the molecular level. Differing from linear poly(2-isopropyl-2-oxazoline) (linear-PiPOx), polymer-rich liquid droplets appear at higher temperature compared with the phase transition determined by differential scanning calorimetry (DSC) in comb-PiPOx solution. As investigated using variable-temperature Fourier transform infrared (FTIR) spectra analysis, the densely grafted architecture gives rise to an intra-molecular interaction (hydrophobic interaction of alkyl groups and H-bond of carbonyl groups) dominating the dehydration process of comb-PiPOx. With temperature increment, most of the water within hydrated polymers is expelled to the outer water phase through intra-molecular association, corresponding to the transition temperature. Afterwards, the dehydration of methyl groups on side chain ends reflects the massive aggregation of polymer chains through inter-molecular association, accompanied by hysteretic LLPS.

Graphical abstract: Intra-molecular interactions dominating the dehydration of a poly(2-isopropyl-2-oxazoline)-based densely grafted polymer comb in aqueous solution and hysteretic liquid–liquid phase separation

Supplementary files

Article information

Article type
Paper
Submitted
16 Dec 2016
Accepted
31 Jan 2017
First published
03 Feb 2017

Phys. Chem. Chem. Phys., 2017,19, 6626-6635

Intra-molecular interactions dominating the dehydration of a poly(2-isopropyl-2-oxazoline)-based densely grafted polymer comb in aqueous solution and hysteretic liquid–liquid phase separation

Y. Zhou, H. Tang and P. Wu, Phys. Chem. Chem. Phys., 2017, 19, 6626 DOI: 10.1039/C6CP08574A

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