Abstract
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.
| Original language | English (US) |
|---|---|
| Article number | 183 |
| Journal | Polymers |
| Volume | 8 |
| Issue number | 5 |
| DOIs | |
| State | Published - Jan 1 2016 |
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All Science Journal Classification (ASJC) codes
- Chemistry(all)
- Polymers and Plastics
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Light and temperature as dual stimuli lead to self-assembly of hyperbranched azobenzene-terminated poly(N-isopropylacrylamide). / Huang, Wenyan; Yang, Jing; Xia, Yunqing; Wang, Xuezi; Xue, Xiaoqiang; Yang, Hongjun; Wang, Guifang; Jiang, Bibiao; Li, Fang; Komarneni, Sridhar.
In: Polymers, Vol. 8, No. 5, 183, 01.01.2016.Research output: Contribution to journal › Article
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
PY - 2016/1/1
Y1 - 2016/1/1
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 -