Controllable Preparation Of Polymer Microlens Structure Induced By Solvent

Microlens arrays(MLA)are micro-optical elements which are widely used in optical sensors,photovoltaics,3D displays as well as light emitting diodes.The growing demand for micro-optical elements has promoted the development of micro-lens manufacturing methods.However,the traditional manufacturing method of microlens depends on expensive equipment and harsh manufacturing environment,which is not conducive to large-scale rapid manufacturing.Therefore,to solve these problems,this paper discusses the method of preparing microlens by solvent induction method,mainly using dewetting method and phase separation method.Through controlling experimental conditions,the size and arrangement of microlens structures are regulated and controlled,and the microlens structures with controllable size arrangement is prepared.In this paper,polystyrene(PS),polymethyl methacrylate(PMMA)and polydimethylsiloxane(PDMS)are used as main materials to prepare microlens structures by solvent-induced dewetting and phase separation methods.The changes of size and arrangement of microlens structures under different experimental conditions are investigated.The aspects are discussed as follows:The preparation of microlens structure is carried out by the method of polymer film dewetting.By adjusting the concentration of polymer solution,the type of solvent vapor and the chemical properties of the substrate,polymer microlens structures with different sizes and adjustable focal lengths are prepared.The influence mechanism of various factors on the size of microlenses is explored by atomic force scanning and other means of method.The result shows that the polymer film prepared with 0.5 wt.%PS solution has the best morphology when silicon wafer modified by octadecyl trichlorosilane is used as the substrate in the vapor environment jointly created by water and toluene.Microlens structure is prepared by phase separation of polymer blends.By changing the initial temperature and time of the phase separation process and adjusting the phase separation stage,polymer microlens structures with different sizes and arrangement modes are controllably prepared.The influence mechanism of temperature and time on the microlens growth stage is explored by means of optical microscope and scanning electron microscope.The result shows that the microlens structure with uniform size and distribution can be obtained when the initial temperature is 65? for 10 min and then 35? for 2 h.Using patterned PDMS substrate,microlens array can be obtained and has good optical imaging capability.