文献类型：会议论文

英文题名：Rheology control by modulating hydrophobic and inclusive associations of side-groups in poly (acrylic acid)

作者：Wang, Jie[1]; Li, Li[1]; Ke, Hailan[1]; Liu, Peng[1]; Zheng, Li[1]; Guo, Xuhong[1]; Lincoln, Stephen F.[2]

机构：[1] State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China; [2] School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia

会议论文集：Chemical engineering in sustainable development Guest Editors: Xuhong Guo and Qingshan Zhu

语种：英文

外文关键词：pH - Hydrophobicity - Ionic strength - Association reactions - Chain length - Rheology - Activation energy - Elasticity - Carboxylic acids - Cyclodextrins

摘要：In this article we demonstrated that the viscosities of modified poly (acrylic acid) (PAA) solutions were tunable by modulating the hydrophobic and inclusion association between alkyl groups and β-cyclodextrin (β-CD) groups grafted to PAA. The viscosity can be controlled by changing the host-guest molar ratio, alkyl chain length, polymer concentration, salt concentration, pH value, temperature, or addition of native β-CD. A viscosity maximum for inclusive polymer networks constructed by mixing hydrophobically modified PAA (HMPAA) and β-CD-modified PAA (β-CDPAA) appeared at the alkyl : β-CD molar ratio of 1 : 1, which implies the inclusion association between HM and β-CD grafts is binary. Longer side chain length or higher polymer concentration led to higher viscosity for aqueous HMPAA solution with only hydrophobic association or its mixture with β-CDPAA with inclusion association. Monotonically increasing the ionic strength or pH value resulted in a viscosity maximum due to the competition between electrostatic repulsion and hydrophobic or inclusive association. The hydrophobic interactions of alkyl groups could be masked by native β-CD, and the networks of HMPAA and β-CDPAA mixture deconstructed upon addition of native β-CD molecules. The storage modulus and loss modulus of hydrophobic HMPAA and inclusive HMPAA + β-CDPAA solutions obey time-temperature superposition. The horizontal and vertical temperature shift factors obeyed a simple-exponential Arrhenius relationship, where the activation energies for hydrophobic association system were found to be 3.4 and -12.1 kJ/mol, and for inclusive association system 53.9 and -2.9 kJ/mol, respectively. ? 2009 Curtin University of Technology and John Wiley & Sons, Ltd.