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以4,4’-二羟乙氧基偶氮苯(BHEAZO)为引发剂引发对二氧环己酮(PDO)开环聚合,与羧基化的单羟甲基聚乙二醇(mPEG)偶联,制备了具有光响应性的两亲性三嵌段共聚物mPEG-BHEAZO-PPDO-mPEG,并对其纳米聚集体的光响应行为进行了研究.采用紫外可见光谱(UV-Vis Spectroscopy)研究了纳米聚集体水溶液的吸光度随着光照时间的变化;用动态光散射(DLS)研究了辐射波长对纳米聚集体的粒径及粒径分布的影响;结合透射电子显微镜(TEM)的研究结果,提出了对纳米聚集体在不同波长光照下聚集行为改变的机理,即反式结构共平面的共轭体系更易形成稳定的低能级电子离域状态,从而使得纳米聚集体之间通过π-π堆积作用形成微聚集现象.
The ring opening polymerization of dioxanone (PDO) with 4,4’-bishydroxyethoxyazobenzene (BHEAZO) as initiator initiated the reaction with carboxylated monohydroxymethyl polyethylene glycol (mPEG) (MPEG-BHEAZO-PPDO-mPEG) was prepared and its photoreaction behavior of nano-aggregates was studied.Using UV-Vis Spectroscopy The influence of the wavelength of radiation on the particle size and particle size distribution of nano-aggregates was studied by dynamic light scattering (DLS). Combined with the results of TEM, The mechanism of the change in aggregation behavior of nano-aggregates at different wavelengths of light is proposed. That is, the coplanar system with a trans-structure coplanar system is more likely to form a stable low-level electron delocalization state, thereby allowing nano-aggregates to pass through π-π stacking The role of the formation of micro-aggregation phenomenon.