侧链含查尔酮基团的聚(甲基)丙烯酸酯的光交联特性

Photocrosslinkable Properties of Poly (meth) acrylates with Pendent Chalcone Moieties

采用红外光谱、热重分析、紫外光谱和荧光光谱对侧链含查尔酮基团的聚(4-甲基丙烯酰氧基-4'-二甲氨基查尔酮)(PMADMAC)和聚(4-丙烯酰氧基查尔酮)(PAC)的光交联特性进行了研究。随着光照时间的增加,PMADMAC和PAC聚合物光致环加成反应迅速进行,波长短的紫外线更易使得聚合物发生[2+2]环加成反应。与溶液状态相比,固体薄膜状态下的光交联反应速率较慢。PMADMAC聚合物更容易发生光致环加成反应,其光交联速率要比PAC聚合物快,环加成反应也更彻底。采用荧光光谱研究了聚合物的发光特性,发现PAC聚合物无荧光,而PMADMAC聚合物具有溶剂极性敏感的荧光特性。在PMADMAC聚合物的稀溶液中,随着365 nm紫外光照时间的增加,荧光强度迅速降低,其荧光特征波长在紫外光照射后发生蓝移。PMADMAC和PAC聚合物的热稳定性较好,光交联后形成热不稳定的环丁烷结构,其热稳定性有所降低。

The photocrosslinking properties of poly ( 4-methacryloyloxy-4’-dimethyl aminochalcone ) ( PMADMAC) and poly(4-acryloyloxychalcone) ( PAC) homopolymers were investigated by Fourier transform infrared spectoscopy ( FT-IR) , thermogravimetric analysis, UV-visible spectroscopy ( UV-Vis) , and fluorescence spectroscopy. Photocrosslinking results of PMADMAC and PAC indicate the photo-induced [2+2] cycloaddition reaction takes place rapidly with the increase of light irradiation time and is carried out easily at presence of shortwave UV light. The photocrosslinking rate of poly-mers in the state of thin film is slower than that of solution due to the limited molecular motion in sol-id. Compared to PAC, the cycloaddition reaction of PMADMAC with intramolecular charge transfer properties takes place more easily and completely, and the photocrosslinking rate more rapidly. The photoluminescent properties were investigated by fluorescence spectroscopic techniques and the re-sults show PMADMAC with solvent polarity sensitive fluorescence and PAC without fluorescence. With the increase of 365 nm UV light irradiation time, the fluorescent intensity of PMADMAC dilute solution decreases drastically and the fluorescent wavelength blueshifts in the late of UV irradiation. Thermogravimetric analysis results show a good thermalstability of PMADMAC and PAC, and a de-crease in thermalstability after the formation of cyclobutane ring by photocrosslinking.