Broadband Light Transmission Regulation In Polymer Microfluidic Composite Systems

Regulating the light transmission process can achieve elaborate energy transfer and efficient information transmission,and has important applications in the fields of energy and military.Due to the inherent characteristics of solid materials and the complexity of processing,the existing technologies are difficult to meet the requirements for precision and bandwidth of optical transmission regulation in energy and military applications.Introducing fluids into optical control systems can achieve high-precision and wide-band optical transmission control,by utilizing the characteristics of flow flexibility,high composability,and controllable morphology.At the same time,polymers are easy to process into different structural forms,providing a platform for fluid management and manipulation.The rich structural forms of polymers can also achieve precise light transmission regulation.Therefore,this dissertation proposes a strategy of using the polymer and microfluidic composite system to achieve the elaborate and broadband light transmission regulation.By utilizing the spectral selective absorption of fluids and the scattering characteristics of porous polymer interfaces,the light transmission process can be regulated over the wide spectral range,achieving precise energy transport and dynamic adjustment of spectral characteristics.The main results and conclusions are as follows:（1）Utilizing the doping medium in polymer fibers and interface bending to regulate light scattering,a polymer optical fiber with uniform luminescence was developed.Firstly,we theoretically analyzed the influence of various dimensional parameters and bending morphology on the lateral light emission effect.It was found that the lateral luminescence intensity can be controlled by doping pores and strengthening the interface bending,and the polymer optical fiber with uniform lateral luminescence can be obtained.Then a uniformly luminescent polymer photoconductive membrane was prepared based on a scattering fiber with side emitting function.The side emitting intensity of the fiber gradually decreased from83.0 m W·m^-2 to 75.5 m W·m^-2.Compared to non-woven fiber bundles,the lateral emission intensity of the photoconductive membrane changed less along the transmission path,and the uniformity of lateral emission was improved.Finally,the purification effect of polymer photoconductive membrane combined with photocatalytic materials on methyl orange solution was tested.The measurement results show that the photocatalytic efficiency of the photoconductive membrane was higher than that of traditional filters that do not have a light guiding effect.The photoconductive membrane can introduce the external light to the interior of water.Combined with photocatalytic technology,the membrane modules with separation and removal functions can be construct,enabling removal of organic pollutants in sewage by using solar energy.（2）Utilizing the selective absorption of light by fluids and the infrared translucency characteristics,a multi-layer microfluidic film to achieve visible and infrared dual-band modulation was proposed.Microfluids are composed of pigment molecules dispersed in paraffin oil.Pigment molecules exhibite the selective absorption characteristics in the visible spectrum.Red,yellow,and blue pigment microfluids exhibit the strongest absorption effects at wavelengths of about 520 nm,400 nm,and 630 nm,respectively.Paraffin oil has a translucent characteristic in mid-infrared spectrum.The absorbance of paraffin oil with a thickness of 100 microns is around 0.2.A polymer film containing three layers of microchannels was prepared using transparent polyethylene.Programmatically controlling the flow of three different colors of paraffin oil within the microchannels,the film can dynamically display different colors,while the infrared emissivity varies in the range of 0.42-0.90.In addition,we have built an experimental device that could automatically control the fluid filling state.The camouflage performance of the microfluidic film was tested simultaneously using a digital camera and an infrared thermal imager.Under 4 different color and temperature backgrounds,the color and apparent temperature of the microfluidic film remained consistent with the background,demonstrating excellent dynamic camouflage ability.（3）Utilizing the selective absorption of fluids and the scattering effect of porous polymers regulated the solar reflection spectra to imitate the spectral characteristics of plant leaves.Combining the spectral regulation with hydrogel temperature regulation,a polymer-fluid bionic leaf was designed to realize the sunlight hyperspectral/mid-infrared/radar compatible camouflage in vegetation environment.The biomimetic leaf is composed of microfluidic fabric,porous polymer and hygroscopic hydrogel from top to bottom.Utilizing the selective absorption characteristics of fluids and the scattering effect of porous polymer,the biomimetic leaf achieved highly similar spectral characteristics to natural leaves in the 300 nm-2500 nm wavelengths,thereby realized hyperspectral stealth.The lower structure of the biomimetic leaf is hygroscopic hydrogel.Simulating transpiration of real leaf by using evaporation-absorption characteristics of hydrogel film,the biomimetic leaf obtained a temperature distribution similar to that of real leaf,and achieved the infrared stealth.In addition,the radar stealth was realized by using the absorbing effect of hydrogel film in radar waves.The outdoor tests showd that the bionic leaf and the real leaf have similar temperature distribution characteristics,and the temperature difference between the bionic leaf and the real leaf is less than 2℃,thus realizing the infrared camouflage under the vegetation environment.In addition,the radar stealth characteristic of biomimetic leaf was tested using a microwave network vector analyzer.In the frequency band of 8.2 to 12.4 GHz,biomimetic blades with a thickness of 5 mm had a reflectivity of less than-10 d B,demonstrating good radar camouflage performance.Under the cooperative action of different structures in the biomimetic leaf,hyperspectral-infrared-radar stealth in the vegetation environment was achieved.