Thermo-responsive and fluorescent cellulose nanocrystals grafted with polymer brushes. Issue 5 (8th December 2014)

• Record Type: Journal Article
• Authors: Wu, Weibing; Huang, Fang; Pan, Shaobo; Mu, Wei; Meng, Xianzhi; Yang, Haitao; Xu, Zhaoyang; Ragauskas, Arthur J.; Deng, Yulin
• Is Part Of: Journal of materials chemistry. Volume 3:Issue 5(2015)
• Page Start: 1995
• Page End: 2005
• Publication Date: 2014-12-08
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c4ta04761c
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Fluorescent and thermo-responsive cellulose nanocrystals (CNCs) with tuned polymer brushes were prepared via surface initiated activators generated by electron transfer for atom transfer radical polymerization. Abstract : Cellulose nanocrystals (CNCs) grafted with fluorescent and thermo-responsive poly( N -isopropylacrylamide) (PNIPAAM) brushes were prepared via surface-initiated activators generated by electron transfer for atom transfer radical polymerization (SI-AGET-ATRP) in the CH3 OH–H2 O mixing solvent with different volume ratios. The successful grafting was supported by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) measurements. Gravimetric analysis plus 1 H NMR and gel permeation chromatography (GPC) measurements showed that there was an increase in the monomer conversion and molecular weight of polymer brushes with increasing H2 O proportion of the solvent system. The variation trend of graft length was further evidenced by the gradual change of decomposition and glass transition temperatures of the surface-grafted CNCs. A large scale of chain transfer occurred on the surface of CNCs in view of the minute quantity of free polymers generated by a sacrificial initiator. Free polymers cannot be used as a substitute to characterize grafted polymers in terms of the big difference between their molecular weights. The obtained surface-grafted CNCs showed thermo-enhanced fluorescence owing to the thermal-driven chain dehydration of the grafted PNIPAAM brushes.