title: Fluorescent cellulose aerogels containing covalently immobilized (ZnS)x(CuInS2)1-x/ZnS (core/shell) quantum dots.
abstract: Photoluminiscent (PL) cellulose aerogels of variable shape containing homogeneously dispersed and surface-immobilized alloyed (ZnS)x(CuInS2)1-x/ZnS (core/shell) quantum dots (QD) have been obtained by (1) dissolution of hardwood prehydrolysis kraft pulp in the ionic liquid 1-hexyl-3-methyl-1H-imidazolium chloride, (2) addition of a homogenous dispersion of quantum dots in the same solvent, (3) molding, (4) coagulation of cellulose using ethanol as antisolvent, and (5) scCO2drying of the resulting composite aerogels. Both compatibilization with the cellulose solvent and covalent attachment of the quantum dots onto the cellulose surface was achieved through replacement of 1-mercaptododecyl ligands typically used in synthesis of (ZnS)x(CuInS2)1-x/ZnS (core-shell) QDs by 1-mercapto-3-(trimethoxysilyl)-propyl ligands. The obtained cellulose-quantum dot hybrid aerogels have apparent densities of 37.9-57.2 mg cm-3. Their BET surface areas range from 296 to 686 m2g-1comparable with non-luminiscent cellulose aerogels obtained via the NMMO, TBAF/DMSO or Ca(SCN)2route. Depending mainly on the ratio of QD core constituents and to a minor extent on the cellulose/QD ratio, the emission wavelength of the novel aerogels can be controlled within a wide range of the visible light spectrum. Whereas higher QD contents lead to bathochromic PL shifts, hypsochromism is observed when increasing the amount of cellulose at constant QD content. Reinforcement of the cellulose aerogels and hence significantly reduced shrinkage during scCO2drying is a beneficial side effect when using α-mercapto-ω-(trialkoxysilyl) alkyl ligands for QD capping and covalent QD immobilization onto the cellulose surface.
authors.affiliation: Key Laboratory of Natural Polymeric Materials and Application Technology, Department of Materials Science and Engineering, Beijing Institute of Technology, Zhongguancun South Street 5, Beijing, 10081 People's Republic of China ; Division of Chemistry of Renewables, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Huiqing
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Natural Polymeric Materials and Application Technology, Department of Materials Science and Engineering, Beijing Institute of Technology, Zhongguancun South Street 5, Beijing, 10081 People's Republic of China.
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Shao
authors.affiliation: Division of Chemistry of Renewables, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Bacher
authors.affiliation: Division of Chemistry of Renewables, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Falk
authors.initials: F
authors.lastname: Liebner
authors.affiliation: Division of Chemistry of Renewables, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rosenau
keywords: Aerogels; Cellulose; Ionic liquids; Photoluminiscence; Quantum dots