Preparation Of Photoresist Based On Thiol-Ene Reaction

Two-photon lithography(TPL)has emerged as a powerful tool to manufacture tailored small-scale objects with complex and sophisticated 3D architectures.However,with the continuous development of lithography technology and the need for the functionality of 3D structures,higher requirements are put forward for photoresists.Traditional acrylate-based photoresists have problems such as weak mechanical properties and poor degradability,which limit the potential of this technology in biological applications.As one of the alternative reactions to acrylate polymerization,thiol-ene polymerization is more controllable.In this paper,we have developed two photoresists based on thiol-ene polymerization,which performed well in mechanical adjustability and degradability that cannot be observed in acrylate systems.These photoresists have great potential in biological applications.The specific works are as follows:(1)Developed a photoresist system containing pentaerythritol tetra(3-mercaptopropionate)(PETMP)and pentaerythritol tetraacrylate(PTTA)with adjustable mechanical properties.We investigated the mechanical properties of photoresists for acrylate self-polymerization and thiol-ene polymerization at different exposure doses.The results show that the thiol-ene polymerization has excellent controllability,and the hardness of the resulting photoresist is linearly related to the exposure dose.At a 350-fold exposure dose,the Young’s modulus of cured photoresist can vary by up to 700-fold times,compared with only 14-fold of that of acrylate photoresist under the same conditions.This photoresist significantly improves the mechanical adjustability of the processed structure.(2)Developed a degradable photoresist containing pentaerythritol tetra(3-mercaptopropionate)(PETMP)and bis(2-methacryloyl)oxyethyl disulfide(DSDMA).Photoresist can be degraded by dithiothreitol in an organic solution or a Tris-HCl buffer(pH=8.8),and the degradation product is soluble in water.Using this photoresist as a substrate for fibroblast and Hela cell growth,the polydopamine-coating photoresist surface can promote cell growth and have no significant toxicity to long-term cell culture.(3)We used the two photoresists above for two photon lithography.PETMP-PTTA photoresist exhibits good printing performance.The hardness of the resulting microcube after changing the exposure dose changes by more than 10-fold.This mechanically controllable lithography material has great potential in the manufacture of micro-devices or micro-scaffolds for biological applications.The microstructures prepared by PETMP-DSDMA photoresist achieve selective degradation in reducing solutions.Combined with its good biocompatibility,the photoresist has a good application in the field of biomedicine and multifunctional biomaterials.