利用具有自組裝能力之兩性高分子及奈米粒子混參材料製作軟性仿生透鏡

Abstract

此篇論文中揭示了一種注入型水晶體材料的開發與光學性質之量測。本實驗以尾端改質且具熱敏感性之泊洛沙姆(Poloxamer)高分子為主體，藉由光起始作用進行交聯，以形成人工水晶體材料。泊洛沙姆之尾端氫氧官能基經由丙烯酰氯反應而形成具有丙烯酸官能基高分子，並經由核磁共振(NMR)及紅外光吸收光譜(FTIR)確認。由於泊洛沙姆高分子具有溶液-凝膠轉變的現象，而凝膠狀態可以防止材料注入水晶體時所造成的滲漏現象。改質過後的泊洛沙姆高分子其溶液-凝膠轉變溫度在濃度低於20%時高於未改質之泊洛沙姆高分子，但濃度若高於22%時則兩者表現幾乎相同。經由光起始交聯的泊洛沙姆水膠的楊氏係數會隨著水膠中未改質的泊洛沙姆高分子比例的增加或紫外光起始時間的減少，其楊氏係數會由230kPa降低到18kPa，但光起始劑濃度的影響卻不明顯。 為了增加泊洛沙姆水膠的折射度以符合水晶體需求，在水膠中加入利用四氯化鈦為原料所製作出的奈米二氧化鈦粒子。四氯化鈦經由水解、中和、沈澱、過濾及膠解的過程，可以做出分散在水溶液狀態下的奈米二氧化鈦粒子溶液。根據泊洛沙姆水膠中奈米二氧化鈦粒子濃度的增加，折射率會從原本的1.355提升至1.407，且含有奈米二氧化鈦粒子之泊洛沙姆水膠在可見光範圍皆有良好的穿透度(~90%)，約略等於人類5歲時水晶體的穿透度。 在變焦實驗中，填入高折射率的泊洛沙姆水膠水晶體囊袋其焦距變化(2.53D)比填入低折射率的水晶體囊袋變化(0.87D)來的大，但平均變焦比例幾乎相同(16.57%)，且皆高於人體水晶體(8.37%)。 此論文中也利用電場擴散的方法來模擬人體水晶體中的折射梯度結構的製作。實驗結果證明，利用電場法在低電場強度時即可使奈米二氧化鈦粒子以輻射的方式進行擴散，形成折射梯度之結構。最後藉由光起始交聯的網狀結構使奈米二氧化鈦粒子被固定在泊洛沙姆水膠中，使具有折射梯度之結構被固定。實驗結果也可看出折射梯度的形成能夠提升透鏡成像之品質。利用以上之實驗結果，我們研發出一種有機/無機混合之新穎性材料，對於人工水晶體之研發具有相當之潛力。

In this study, the potentiality to investigate hydrogel which can be injected into crystalline lens is studied. Hydrogel base on thermo-sensitive poloxamer 407 block copolymer is prepared by photo-polymerization. The terminal hydroxyl groups in poloxamer 407 are acrylated to form poloxamer 407 macromer as the reactive polymer, and is confirmed using NMR and FTIR spectrometry. The lower critical sol-gel temperature of poloxamer 407 macromer is higher than poloxamer 407 itself when the concentration is below 20%, but not significant above 22%. The Young’s modulus would be decreased according to the higher ratio of poloxamer 407 that in poloxamer hydrogel or shorter UV irradiation times, but the concentration of photo initiator is not significant. In order to increase the refractive index of poloxamer hydrogel, titanium dioxide nanoparticle is introduced using the titanium (Ⅳ) chloride as titanium source. Titanium chloride through the process of hydrolysis, adjust pH, precipitate and acid-peptization can get the rutile phase titanium dioxide nanoparticles solution. The refractive index of poloxamer hydrogel can increase from 1.355 to 1.407 according to the concentration of titanium dioxide nanoparticles, and all samples had a good transmission (~90%) comparable to a 5-year-old natural crystalline lens. Stretch and unstretch experiment shows the PDMS capsule which filled with the highest refractive index poloxamer hydrogel has the largest change of diopter (2.53D), and the lowest refractive index poloxamer hydrogel shows the smallest change (0.87D). The average change ability is 16.57%, better than the human crystalline lens, about 8.37%. The gradient refractive index structure in the human crystalline lens also reconstruct by using the electric field method. The distribution of titanium dioxide nanoparticles can be controlled by electric field in poloxamer hydrogel, which presents the radial gradient refractive index profiles. Finally we cross-linked poloxamer hydrogel that the gradient refractive index structure can be maintained. The experiment data also show the gradient refractive index does have the ability to increase the image quality. The novel organic/inorganic hybrid materials show the potential to be used for crystalline lens applications.