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Characterization of photo‐ and thermoresponsible amphiphilic copolymers having azobenzene moieties as side groups
Author(s) -
Sugiyama Kazuo,
Sono Kazuro
Publication year - 2001
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1756
Subject(s) - polymer chemistry , azobenzene , copolymer , lower critical solution temperature , methacrylamide , monomer , azobisisobutyronitrile , methacrylate , radical polymerization , chemistry , materials science , polymer , organic chemistry , acrylamide
Abstract Two series of amphiphilic copolymers, poly(HPMA‐ co ‐MPAP) I–V with n = 0.05–0.29 of the molar ratio of MPAP and poly(HPMA‐ co ‐MPAH)‐I–V with n = 0.05–0.23 of the molar ratio of MPAH, were prepared by radical copolymerization of N ‐(2‐hydroxypropyl) methacrylamide (HPMA) with azo‐monomers such as 4‐(4‐methoxyphenylazo) phenyl methacrylate (MPAP) and 6‐[4‐(4‐methoxyphenylazo) phenoxy] hexyl methacrylate (MPAH) using 2,2′‐azobisisobutyronitrile as an initiator. Self‐organization of these copolymers in water was confirmed by disappearance of the proton signal of the methoxyazobenzene in 1 H‐NMR spectra measured in the solvent system of D 2 O and CD 3 OD. It was also found from the λ max , located near 344 nm, that azobenzene groups self‐organized to form the dimeric chromophore type of aggregate. The aqueous solutions of poly(HPMA‐ co ‐MPAP) and poly(HPMA‐ co ‐MPAH) exhibited the lower critical solution temperature (LCST) from at 68 to 40°C and from at 70 to 52°C in the dark state, respectively, with increasing the molar ratios of azo‐monomers. On the other hand, the LCST measured in the photostationary state showed the higher temperature by 2–4°C compared with that in the dark state. It was found that the adsorption of poly(HPMA‐ co ‐MPAP)‐V ( n = 0.29) on polystyrene microspheres was photoregulated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3056–3063, 2001