SYNTHESIS AND PHOTO-RESPONSIVE BEHAVIORS OF HOLLOW POLYAZOBENZENE MICRO-SPHERES
(0) By means of distillation precipitation polymerization, the silica-hybrid particles with polyazobenzene shell (Pazo@SiO_2) microspheres were prepared with 6-(4-methoxy-4-oxy-azobenzene) hexyl methacrylate (Azo-M) as monomer, divinylbenzene (DVB) as cross-linker, and ~250 nm vinylated sol-gel silica particles as template. Hollow Pazo microspheres were further developed after selective removal of the silica cores with HF solution (Figure 1). These hollow Pazo microspheres have excellent reversible photoisomerization behaviours by UV irradiation.1-5 The isomerization of the trans-azobenzene group into cis-azobenzene makes the dispersion of hollow Pazo microspheres turn opaque (Scheme 1). It might be caused by the variation of the polarity. The hollow Pazo microspheres with azobenzene units in the trans conformation can be well dispersed in nonpolar toluene. Under UV irradiation, the azobenzene units isomerize into the cis isomer with a higher polarity, and some hollow Pazo microspheres precipitate in nonpolar toluene solvent6 N_2 adsorption/desorption isotherms indicate the increased specific surface area from 18.87 to 20.83 m_2/g under UV irradiation (Figure 2). The bent conformation of the cisazobenzene might be more useful to the adsorpotion of N_2.7 The change of the azobenzene transformation in the shell acts as a switch which might be used as an effective way to develop novel high-performance photo-responsive materials.
Xiaotao Wang Yonggui Liao Zhifang Yang Xiaolin Xie
School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
国际会议
PP’2010，Jinan International Symposium on Polymer Physics(2010济南国际高分子物理学术研讨会)
济南
英文
374-375
2010-06-06（万方平台首次上网日期，不代表论文的发表时间）