【作者】 刘玲；

【导师】 邢金峰；

【作者基本信息】 天津大学 ， 应用化学， 2016， 硕士

【摘要】 双光子吸收(Two-photon absorption,TPA)是一种三阶非线性光学过程,是指强光激发下,分子通过同时吸收和结合两个低能量的光子(两个光子的能量可以相同也可以不同),诱导分子跃迁到激发电子态的过程。基于双光子吸收特性的双光子聚合具有空间选择性高、长波激发短波发射和穿透深度大等优点。因此利用在介质中穿透力强、入射损耗小的近红外激光作为光源的双光子聚合微加工(Two-photon polymerization microfabrication,TPPM)可制备任意的三维微结构,且微结构的分辨率已经超过瑞利判据的光学衍射极限,是一种比较先进的3D直写打印技术。近年来,该技术广泛用于三维信息存储、光子晶体和光波导等光学元件加工。最近TPPM加工用于组织工程和药物递送的3D水凝胶是研究的热点,水凝胶是含水量与软组织相似的聚合物材料。但是TPPM引发剂多为疏水性化合物,需要在有机溶剂体系的树脂中进行,导致部分有机溶剂残留在加工的3D水凝胶微结构中。目前,该领域急需解决的关键问题是:研制水溶性的高活性双光子聚合引发剂,并且提高用水溶性引发剂加工的微结构的分辨率,因为高分辨的3D水凝胶在组织工程和药物递送方面具有重要的作用。针对这一问题,本研究以亲疏水组装的方法来制备水溶性双光子聚合引发剂,并对制备的水溶性双光子聚合引发剂的光学性质和加工性能进行了系统的研究,加工出了分辨率为92 nm的水凝胶线,首次将3D水凝胶的分辨率降到100 nm以下。首先,利用两亲性的泊洛沙姆(PF127)与具有高引发活性引发剂2,7-二(4-戊烷氧基-苯乙烯)-蒽醌进行亲疏水组装,制备水溶性的双光子聚合引发剂(WTPPI)使得水溶性增大,实现水相中生物相容性单体的双光子聚合。WTPPI在波长为780 nm处的双光子吸收截面为200 GM,这比之前报导的水溶性引发剂的双光子吸收截面大很多。引发单体(聚乙二醇丙烯酸酯)聚合的阈值是6.29m W(引发剂在树脂中的摩尔分数是0.03%)。横向分辨率为92 nm。该阈值比最近报导的水相中双光子聚合的阈值8.6 mW低很多,并且首次将水凝胶的分辨率提高到100 nm以下。研究了固定扫描速度和激光功率对线宽的影响,在激光能量为9 mW、扫描速度为10μm/s下,加工了完整的天津大学校徽二维结构。固定扫描速度为110μm/s,在激光能量分别为7.27 mW、9.46 m W、11.27 mW下,加工了精细的三维腺病毒结构,研究激光能量对结构精细度的影响。并加工了碳纳米管结构,研究水凝胶对PH的响应性。我们的3D水凝胶微纳结构加工的研究为其在生物医学方面的应用奠定了基础。更多还原

【Abstract】 Two-photon absorption(Two-photon absorption,TPA)is a kind of third order nonlinear optical process.Which refers to under strong light excitation,molecule could absorb and combine both low energy photons simultaneously(The energy can be the same or different),then molecular is induced to the excited electronic state.This process has many advantages,such as high three-dimensional spatial selectivity,emitting shorter wavelength light with absorbing longer wavelength light with lower energy and high penetration depth.Two-photon polymerization occurs only in the laser focus.TPPM is an advanced 3D print technology and can fabricate arbitrary 3D microstructure,because the wavelength of laser source used in TPP is infrared laser which can penetrate a large depth with a little loss.The resolution of 3D microstructure fabricated by TPPM has beyond the optical diffraction limit.In recent years,TPPM technology has been widely used in 3D information storage,photonic crystals and waveguides fabrication.Recently,the researchers pay close attention to 3D hydrogels(Hydrogels are commonly referred to as polymeric materials with water contents similar to those of soft tissues)fabricated by TPPM,which are important for tissue engineering and drug delivery.However,a large proportion of high efficiency TPPM initiators are hydrophobic and TPPM has to be reacted in organic solvent,giving rise to residue of organic solvent in 3D hydrogels with serious cytotoxicity which hinders the biomedical application of 3D hydrogels.At present,we obtain water soluble TPPM initiator with high efficiency is the important questions in the field.In this study,a water soluble two-photon polymerization(TPP)initiator(WTPPI)with high initiating efficiency was prepared by using a poloxamer(PF127)to encapsulate 2,7-bis(2-(4-pentaneoxy-phenyl)-vinyl)anthraquinone via a hydrophilic-hydrophobic assembly.The properties of their optical and fabrication were investigated.Finally,two-photon polymerization could occur in aqueous phase.Firstly,we prepared a water soluble TPP initiator(WTTPI)by using a poloxamer(PF127)to encapsulate 2,7-bis(2-(4-pentaneoxy-phenyl)-vinyl)anthraquinone which is an efficient initiator has been reported by our group via a hydrophilic-hydrophobic assembly.The water solubility of new compound increase and biocompatibility monomer could be polymerized in aqueous.In aqueous medium,the δTPA value of WI is around 200 GM at 780 nm which is much larger compared with those of commercial initiators and most of the water soluble TPA materials reported with a low δTPA less than 100 GM.The threshold energy of TPP for the resin with poly(ethylene glycol)diacrylate(PEGda)as monomer and WTPPI as photoinitiator(the molar ratio of N in resin is 0.03%)was 6.29 mW.Which was much lower than those reported previously 8.6 mW.A lateral spatial resolution of 92 nm was achieved as the resolution breakthrough of 3D hydrogels under 100 nm.In the study,we fixed the scanning speed and research the laser power effect on the line width.We fabricated perfectively school badges of Tianjin University by using an average of 9 mW and a scanning speed of 10 μm/s.On the other hand,we studied the laser power effect on the resolution of 3D microstructure.The adenovirus were fabricated by using scanning speed of 110 μm/s and average power of 7.27 m W,9.46 mW and 11.27 m W,respectively.The studies lay important foundation for 3D hydrogels applied in biomedical fields.更多还原