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Journal of Nanomaterials
Volume 2012, Article ID 749732, 10 pages
http://dx.doi.org/10.1155/2012/749732
Research Article

Star Poly(N-isopropylacrylamide) Tethered to Polyhedral Oligomeric Silsesquioxane (POSS) Nanoparticles by a Combination of ATRP and Click Chemistry

1Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
2Institute of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan

Received 7 January 2012; Accepted 21 February 2012

Academic Editor: Luis Antonio Sanchez de Almeida Prado

Copyright © 2012 Shiao-Wei Kuo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

New star poly(N-isopropylacrylamide)-b-polyhedral oligomeric silsesquioxane (PNIPAm-b-POSS) copolymers were synthesized from octa-azido functionalized POSS (N3-POSS) and alkyne-PNIPAm, which was prepared using an alkyne-functionalized atom transfer radical polymerization (ATRP) initiator (propargyl 2-bromo-2-methylpropionamide), via click chemistry. These star PNIPAm-b-POSS copolymers undergo a sharp coil-globule transition in water at above 32°C changing from a hydrophilic state below this temperature to a hydrophobic state above it, which is similar to linear PNIPAm homopolymers. More interestingly, we found that these star polymers exhibited strong blue photoluminescence in water above a lower critical solution temperature (LCST). This photoluminescence was likely due to the constrained geometric freedom and relatively rigid structure caused by intramolecular hydrogen bonding within the star PNIPAm polymers, which exhibit an intrinsic fluorescent behavior.