Utilizing the Photothermal Effect of Metal Nanoparticles for Processing of Polymers

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This grant provides funding to investigate the use of light-activated heating (photothermal effect) of metal nanoparticles embedded in a polymer composite as a tool for material processing and actuation. In this photothermal process, irradiation with visible light tuned to the specific nanoparticle properties results in nanoparticle heating and local transfer of energy to the surrounding polymer. Measurements of the internal temperature within the composite will be utilized to determine the nanoparticle concentration and light intensity required to cure, melt, or actuate. Photothermal activation of shape memory polymers (materials that alter their shape or size upon temperature change) will be compared with actuation via traditional heating methods. Changes in mechanical strength and modulus due to photothermal heating of nanofibrous samples will also be studied. Multi-component samples where nanoparticles are limited to a specific region will be investigated to test the spatial specificity of the heating. If successful, the results of this research will enable new processing approaches for polymeric materials, where heat is applied from within rather than from the exterior, enabling the internal temperature to exceed that of the material surface. Polymeric structures could be cross-linked to improve strength, be repaired, or undergo a shape change at a working location while avoiding significant increase in the temperature of the surroundings. The selective placement of nanoparticles would enable heating of specific regions to allow for melting, curing, or re-crystallization, while the remainder of the material would be unaffected. In this manner, materials with new hybrid properties can be designed and developed.