Oggioni Luca, Toccafondi Chiara, Pariani Giorgio, Colella Letizia, Canepa Maurizio, Bertarelli Chiara, Bianco Andrea
INAF-Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate, Italy.
Dipartimento di Chimica, Materiali ed Ingegneria Chimica, Politecnico di Milano, p.zza L. Da Vinci 32, 20133 Milano, Italy.
Polymers (Basel). 2017 Sep 20;9(9):462. doi: 10.3390/polym9090462.
Photochromic polymers have been studied as rewritable systems for optical elements with tunable transparency in the visible and refractive index in the NIR. Six diarylethene monomers have been synthesized to give thin films of photochromic polyurethanes. The absorption properties of the monomers in solution and of the corresponding polymeric films have been evaluated showing that a transparency contrast in the visible spectrum of the order of 10 3 can be obtained by a suitable choice of the chemical structure and illumination wavelength. The change in the refractive index in the NIR have been determined by ellipsometry showing changes larger than 10 - 2 . A trend of this variation with the absorption properties has been also highlighted. Fresnel lenses working on the basis of both a change of the transparency and the refractive index (amplitude and phase) have been demonstrated.
光致变色聚合物已被作为用于光学元件的可重写系统进行研究，该系统在可见光范围内具有可调透明度，在近红外范围内具有可调折射率。已合成六种二芳基乙烯单体以制备光致变色聚氨酯薄膜。已评估了单体在溶液中的吸收特性以及相应聚合物薄膜的吸收特性，结果表明，通过适当选择化学结构和照明波长，可在可见光谱中获得约10³的透明度对比度。通过椭偏测量法确定了近红外范围内的折射率变化，结果表明变化大于10⁻²。还突出显示了这种变化与吸收特性的趋势。已经证明了基于透明度和折射率（幅度和相位）变化工作的菲涅耳透镜。
