title: Hansen solubility parameter analysis on the dispersion of zirconia nanocrystals.
abstract: Nanoparticle dispersible in a broad range of solvents is desirable when preparing an organic/inorganic nanocomposite. In this report, the dispersion behavior of carboxylate-grafted zirconia nanoparticle in 25 solvents covering a wide range of polarity was analyzed based on their Hansen solubility parameters (HSP). Particles grafted with alkyl-chain longer than four carbons could only be dispersed in non-polar solvents, while that grafted with acetic acid was dispersible in polar ones. However, particle modified with methacrylic acid (MA) was compatible with both types of solvents, which was rather unexpected. Further NMR analysis showed that the carboxylate-grafted samples contained a trace amount of triethanolamine (TEA) due to the particular ZrO2 synthesis process employed. The combination of the hydrophilic TEA ligand with the short hydrophobic tail of methacrylate broadened the range of compatible solvents from benzene to methanol. Such an extended solvent compatibility was observed previously only for nanoparticles covered with large polymer surfactants having both hydrophilic and hydrophobic groups. Achieving this with two small molecules having separate functional groups is crucial when one needs to maximize the inorganic content in a composite.
authors.affiliation: Department of Chemical and Materials Engineering, National Central University, Chung Li 320, Taiwan, ROC. 973404004@cc.ncu.edu.tw
authors.forename: Sho-Hsun
authors.initials: SH
authors.lastname: Wang
authors.forename: Jia-Hong
authors.initials: JH
authors.lastname: Liu
authors.forename: Chin-Tung
authors.initials: CT
authors.lastname: Pai
authors.forename: Chien-Wei
authors.initials: CW
authors.lastname: Chen
authors.forename: Pao-Tang
authors.initials: PT
authors.lastname: Chung
authors.forename: Anthony Shiaw-Tseh
authors.initials: AS
authors.lastname: Chiang
authors.forename: Shinn-Jen
authors.initials: SJ
authors.lastname: Chang
keywords: Carboxylic acid; Dual-ligand; NMR; Nanocomposite; Refractive index; Solvent compatibility; Surface modification; Transparent sol; Triethanolamine