| Hydrogel is a hydrophilic polymer material with a three-dimensional(3D)cross-linked network structure.It has good biocompatibility and is similar to extracellular matrix in the organism,so it has potential application value in biomedical field.Among them,the 3D hydrogel with high precision can better simulate the microenvironment of organisms.Two-Photon Polymerization Microfabrication(TPPM)provides a simple and effective method for preparing precise-structured 3D hydrogel.Two-photon polymerization only occurs in a very small area at the laser focus,so the prepared hydrogel has a relatively high resolution.In the research of TPPM,most photoinitiators are oil-soluble.The preparation of water-soluble photoinitiator for TPPM hydrogels can avoid adding organic solvent to photoresist.At present,the research of water-soluble photoinitiators still has the problems of low solubility of photoinitiators in water and high laser energy used in TPPM.Therefore,research on photoinitiators with high water solubility and low threshold is an urgent problem in this field.In this thesis,two water-soluble photoinitiators were synthesized via host-guest interaction,and a series of characterizations were carried out.The micromachining characteristics of water-soluble photoinitiators formulated into photoresists were studied.First,water-soluble benzil(WS-Benzil)is prepared via host-guest interaction between 2,6-dimethyl-?-cyclodextrins and oil-soluble photoinitiator Benzil.It were characterized by nuclear magnetic,infrared,ultraviolet,fluorescence,biocompatibility and so on.Water-soluble photoresist was prepared with WS-Benzil as a photoinitiator,and the characteristics of UV lamp polymerization and two-photon micromachining were studied respectively.The experimental results show that the solubility of WS-Benzil in water was determined to be 70 g / 100 mL at room temperature,which is dozens of times of that reported previously.In the ultraviolet lamp polymerization experiment,the water-soluble photoresist was polymerized into a light yellow film.The polymerized film has a uniform surface and good transmittance.In the two-photon polymerization micromachining experiment,the polymer lines were processed by photoresists with different water content.When the water content was 20 wt%,the threshold was reduced to 0.3 mW.When the water content was 70 wt%,the spatial resolution was increased to 92 nm.By adjusting the laser power,scanning speed and layer spacing in TPPM,the influence of these three parameters on the microstructure morphology was studied.And by changing the water content in the photoresist,the wide range of water content can be adjusted.Secondly,water-soluble photoinitiator 369(WS-PI369)is prepared via host-guest interaction between 2,6-dimethyl-?-cyclodextrins and oil-soluble 2-benzyl-2-(dimethylamino)-4?-morpholinobutyrophenone(water-soluble photoinitiator 369,PI369).It were characterized by nuclear magnetic,infrared,ultraviolet,fluorescence,biocompatibility and so on.Water-soluble photoresist was prepared with WS-PI369 as a photoinitiator,and the characteristics of UV lamp polymerization and two-photon micromachining were studied respectively.The experimental results show that the solubility of WS-PI369 in water was determined to be 48 g / 100 mL at room temperature,which is dozens of times of that reported previously.In the ultraviolet lamp polymerization experiment,the water-soluble photoresist was polymerized into a light yellow film.The polymerized film has a uniform surface and good transmittance.In the two-photon polymerization micromachining experiment,the surface of the processed polymer lines were smooth.The threshold was reduced to 1.9 mW and the spatial resolution was increased to 114 nm.The processed geometry,quadrangular pyramid and OK gesture hydrogel microstructure have the characteristics of clear outline and good surface morphology. |
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