Fabrication, functionalization, and exploration of polymer -based rancdevices

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We experimentally presented proof that several mechanical properties of polymer, such as elasticity, viscoelasticity, and glass transition temperature, are dependent on the size of the polymer in nano meter scale. To our knowledge, this result is the first report of the size -effect on mechanical property of nano materials. We fabricated nano spring made of 〜200 nm diameter poly (methylmethacrylate) nanowire by means of two-photon photopolymerization. We manipulated the fabricated nano spring in solution by laser trapping method, and measured the spring constant of the nano spring. We installed temperature controllable stage into our hand -made laser trapping system, which made it possible to change the temperature of the nano spring from about 200 to 400 K during spring constant measurement. First, we found that the elasticity of nano size polymer is 109 times smaller than that of the bulk of the same material. This giant elasticity is not related to degree of polymerization, or solve … More nt, but purely dependent on the size of polymer. We also observed that transition temperature of the polymer changes remarkably depending on the size of polymer. Actually, the transition temperature decreased more than 40 K when the size of the nano spring was decreased from 450 nm to 150 nm. The experimental data also suggest a novel functionality in polymer based nano devices, which is reversible temperature -switchable elasticity/viscoelasticity. The change of elasticity/viscoelasticity by transition temperature is actually intrinsic in any polymer materials, and so not surprising, though the glass transition temperature of bulk polymer is usually 〜370 K. However by designing the size of polymer structures at the nanoscale, it becomes possible to control the switching temperature, even at room temperature. We also developed new polymer materials functionalized by az o-benzene contained monomers. This polymer shows refractive index change and volume change by light irradiation. We fabricated three -dimensional photonic crystals by two-photon polymeriation, and demonstrated optical switching of photonic bandgaps. Since the refractive index and volume change is induced by photo -isomerization of azo-benzene derivative, the optical switching of photonic bandgaps is reversible. These novel mechanical and optical functions we have shown through this project are intrinsic to nano-sized polymers, and would lead to exploring future novel polymer-based nanodevices. Less