Cellulose

, Volume 20, Issue 1, pp 67–81

Study on the thermoresponsive two phase transition processes of hydroxypropyl cellulose concentrated aqueous solution: from a microscopic perspective

Original Paper

DOI: 10.1007/s10570-012-9816-z

Cite this article as:
Jing, Y. & Wu, P. Cellulose (2013) 20: 67. doi:10.1007/s10570-012-9816-z

Abstract

In this paper, it was discovered that during the heating process from 35 to 63 °C, hydroxypropyl cellulose (HPC) concentrated aqueous solution (20 wt%) would first go through coil-to-globule transition and then sol–gel transition with temperature elevation. The microdynamic mechanisms of the two phase transitions were thoroughly illustrated using mid and near infrared spectroscopy in combination with two-dimensional correlation spectroscopy (2Dcos) and perturbation correlation moving window (PCMW) technique. Mid infrared spectroscopy is an effective way to study the hydrophobic interactions in HPC molecules. And near infrared spectroscopy is a potent method to study hydrogen bonds between HPC molecules and water molecules. Boltzmann fitting and PCMW could help determine the exact transition temperatures of each involving functional groups in the two processes. Moreover, 2Dcos was used to discern the sequential moving orders of the functional groups during the two phase transitions. Depending on the structure of HPC and the thermodynamic conditions, the dominating associative elements in either process might vary. During the coil-to-globule transition, HPC molecules precipitated to form an opaque system with mobility.It was discovered that the driving force of the coil-to-globule transition process in microdynamics could only be the dehydration and hydrophobic interactions of C–H groups. However, in the sol–gel transition, the system crosslinked to form a physical network with no mobility. The driving force of this process in microdynamics was primarily the self-assembly behavior of O–H groups in HPC “active molecules”.

Keywords

Hydroxypropyl celluloseTwo-dimensional correlation spectroscopyCoil-to-globule transitionSol–gel transitionHydrophobic interactionsHydrogen bonding

Supplementary material

10570_2012_9816_MOESM1_ESM.pdf (153 kb)
Supplementary material 1 (PDF 153 kb)

Copyright information

© Springer Science+Business Media Dordrecht 2012

Authors and Affiliations

  1. 1.State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, and Laboratory of Advanced MaterialsFudan UniversityShanghaiChina