Controllable Fabrication Of The Polymer Microstructure Films Based On Breath Figures

As a new type of functionalized material,microstructures play an increasingly important role in the fields of electronics,optics,biology and separation.However,expensive equipments and harsh reaction conditions are needed in traditional methods of preparing microstructures,besides mass-produced cannot be used in traditional methods.In this article,we had raised a breath figures method via a quickly self-assembly process.Both the size and the morphology of the as-prepared microstructures could be controlled by tuning the experimental conditions.In this work,polyethylene glycol(PEG)and polystyrene(PS)were introduced to assist the ordered array of water droplets,and generated the honeycomb micro-porous films at last.In order to confirm the certain factors on the final morphology and size for the microstructures,two sections had been discussed as followed:Firstly,we had prepared the honeycomb porous films via the traditional breath figures method.Here,the types of organic solvents,the concentration of polymers,the types of substrates,and the presented of small molecule surfactants had been changed to control the morphology of the prepared microstructures.As a result,when the solvent was CCl4,the concentration was 8%,the substrate was Si,and the small molecule surfactants presented,porous polymer films with best parameters could be prepared.The mechanism for the formation of the microstructures was also discussed.Through the finite element analysis method,the concentration distribution of PEG via the breath figures process was simulated.And it has been proved PEG can aggregate on the water-oil surface rather than fill in the water droplets,which can explain that the microlens cannot be prepared in one-step traditional breath figures method.Secondly,we improved the traditional breathing figures method.By introducing a pre-phase separation process,the initial distribution of PEG in the solution was changed,which could probably result in the preparation of microlens arrays only through the one-step breath figure procedure.By regulating the pre-phase separation process,pre-phase separation time,the molecular weight of PEG,the ratio of small molecular weight PEG to high molecular weight PEG,and the molecular weight of PS,the size and morphology of the as-prepared films were also different.We also speculated the formation mechanism of the structures.And we found when the pre-phase separation time was 10 min,the ration of small molecular weight PEG to high molecular PEG was 3:7,and the molecular weight of PS was 18000,polymer films with microlens arrays could be prepared through one-step breath figure procedure.