Fabrication of Photochromic films by Electrolytic and Oxidation Polymerization

光致变色分子因其在光学存储、开关等光学器件中的潜在应用而受到人们的广泛关注。在光致变色化合物中，二芳基乙烯类化合物因其同分异构体的热稳定性和抗疲劳性能而被认为是最好的候选化合物。为了制备用于应用的光致变色薄膜，人们采用了各种方法。将光致变色分子分散到聚合物基质中是制备光致变色薄膜最方便的方法。虽然提高染料浓度是提高光致变色效率的迫切需要，但由于长期储存后会发生一定程度的偏析，因此制备高浓度染料的薄膜并非易事。块体非晶和晶态光致变色薄膜已被广泛研究。我们现在提出了一种形成薄…的新方法以市售的2，4-二溴-3，5-二甲基噻吩为原料合成了二芳基乙烯衍生物1，2-bis[2，4-dimethyl-5-(o-hydroxy-phenyl)-3-thienyl]-hexafluorocyclopentene(1a)。用类似的方法合成了异构体1，2-bis[2，4-dimethyl-5-(m-hydroxyphenyl)-3-thienyl]-hexafiuorbcyclopentene(2a)。在280 nm紫外光照射下，La的溶液变为红色，并在545和347 nm处出现闭环异构体1b的吸收峰，1a的254 nm吸收峰被抑制。在可见光照射下，红色被漂白并再生为开环异构体La。1的环化和环化反应的量子产率分别为0.19(280 nm光照射)和0.03(492 nm光照射)。二芳基乙烯1a按Hay方法聚合，制备的聚合物薄膜p(1a)在紫外光和可见光交替照射下表现出可逆光致变色反应。经X-射线衍射仪测定，在室温下放置1年后仍未出现峰。这表明聚合物薄膜处于无定形状态。这种新的非晶光致变色薄膜将应用于光波导和新型记录介质。较少

Photochromic molecules attract much attention from both fundamental as well as practical points of view because of their potential for applications to optical devices such as optical memories and switches, Among the photochromic compounds, diarylethenes are regarded as the best candidate, because of the thermal stability of their both isomers and the fatigue resistant property. For the fabrication of thin photochrbmic films for the applications, various methods have been employed. Dispersing the photochromic molecules into polymer matrices is the most convenient method to prepare the photochromic films. Although increment of the dye concentration is strongly desired to enhance the photochromic efficiency, preparation of films containing high concentration of the dyes is not easy because segregation takes place to some, extent after long term storage. Bulk amorphous and crystalline photochromic films have been extensively studied for the purpose. We now propose a new method to form thin … More films by oxidation polymerization.A diarylethene derivative 1,2-bis[2,4-dimethyl-5-(o-hydroxy-phenyl)-3-thienyl]-hexafluorocyclopentene (1a) was synthesized from commercially available 2,4-dibromo-3,5-dimethylthiophene. The isomer 1,2-bis[2,4-dimethyl-5-(m-hydroxyphenyl)-3-thienyl]-hexafiuorbcyclopentene (2a) was also synthesized by similar method. Upon UV light (280 nm) irradiation, the solution of la turned to red and absorption bands appeared at 545 and 347 nm attributable to the closed-ring isomer 1b, and the peak of 1a at 254 nm was suppressed. Upon visible light irradiation, the red color was bleached and regenerated the open-ring isomer la. The quantum yields of cyclization and cycloreversion of 1 were 0.19 (measured by 280 nm light irradiation) and 0.03 (measured by 492 nm light irradiation), respectively.The diarylethene 1a was polymerized according to Hay's method The prepared polymer film p(1a) showed a reversible photochromic reaction by alternate irradiation with UV and visible light. X-ray diffraction measurement showed no peaks even after 1 year storage at room temperature. This indicates that the polymer film is in the amorphous phase. The new amorphous photochromic film will be applicable for wave-guide and novel recording media. Less