TY - JOUR
T1 - Light and temperature as dual stimuli lead to self-assembly of hyperbranched azobenzene-terminated poly(N-isopropylacrylamide)
AU - Huang, Wenyan
AU - Yang, Jing
AU - Xia, Yunqing
AU - Wang, Xuezi
AU - Xue, Xiaoqiang
AU - Yang, Hongjun
AU - Wang, Guifang
AU - Jiang, Bibiao
AU - Li, Fang
AU - Komarneni, Sridhar
N1 - Funding Information:
The financial support of this work by the National Natural Science Foundation of China (Nos. 21474010 and 21104006), a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (No. 15KJB150002), and the program of the Innovative Research Team of Changzhou University (No. ZMF1002118) is gratefully acknowledged.
Publisher Copyright:
© 2016 by the authors.
PY - 2016
Y1 - 2016
N2 - Hyperbranched poly(N-isopropylacrylamide)s (HBPNIPAMs) end-capped with different azobenzene chromophores (HBPNIPAM-Azo-OC3H7, HBPNIPAM-Azo-OCH3, HBPNIPAM-Azo, and HBPNIPAM-Azo-COOH) were successfully synthesized by atom transfer radical polymerization (ATRP) of N-isopropylacrylamide using different azobenzene-functional initiators. All HBPNIPAMs showed a similar highly branched structure, similar content of azobenzene chromophores, and similar absolute weight/average molecular weight. The different azobenzene structures at the end of the HBPNIPAMs exhibited reversible trans-cis-trans isomerization behavior under alternating UV and Vis irradiation, which lowered the critical solution temperature (LCST) due to different self-assembling behaviors. The spherical aggregates of HBPNIPAM-Azo-OC3H7 and HBPNIPAM-Azo-OCH3 containing hydrophobic para substituents either changed to bigger nanorods or increased in number, leading to a change in LCST of 2.0 and 1.0°C, respectively, after UV irradiation. However, the unimolecular aggregates of HBPNIPAM-Azo were unchanged, while the unstable multimolecular particles of HBPNIPAM-Azo-COOH end-capped with strongly polar carboxyl groups partly dissociated to form a greater number of unimolecular aggregates and led to an LCST increase of 1.0°C.
AB - Hyperbranched poly(N-isopropylacrylamide)s (HBPNIPAMs) end-capped with different azobenzene chromophores (HBPNIPAM-Azo-OC3H7, HBPNIPAM-Azo-OCH3, HBPNIPAM-Azo, and HBPNIPAM-Azo-COOH) were successfully synthesized by atom transfer radical polymerization (ATRP) of N-isopropylacrylamide using different azobenzene-functional initiators. All HBPNIPAMs showed a similar highly branched structure, similar content of azobenzene chromophores, and similar absolute weight/average molecular weight. The different azobenzene structures at the end of the HBPNIPAMs exhibited reversible trans-cis-trans isomerization behavior under alternating UV and Vis irradiation, which lowered the critical solution temperature (LCST) due to different self-assembling behaviors. The spherical aggregates of HBPNIPAM-Azo-OC3H7 and HBPNIPAM-Azo-OCH3 containing hydrophobic para substituents either changed to bigger nanorods or increased in number, leading to a change in LCST of 2.0 and 1.0°C, respectively, after UV irradiation. However, the unimolecular aggregates of HBPNIPAM-Azo were unchanged, while the unstable multimolecular particles of HBPNIPAM-Azo-COOH end-capped with strongly polar carboxyl groups partly dissociated to form a greater number of unimolecular aggregates and led to an LCST increase of 1.0°C.
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U2 - 10.3390/polym8050183
DO - 10.3390/polym8050183
M3 - Article
AN - SCOPUS:84969988347
VL - 8
JO - Polymers
JF - Polymers
SN - 2073-4360
IS - 5
M1 - 183
ER -