Activation of metal nanoparticle/polymer systems via photothermal effect to develop shape memory polymers

Nanoparticles, known to have superior properties; are considered in a wide range of applications in the field of photonics, optoelectronics, biological and magnetic practices. Photothermal effect due to surface plasmon resonance in metal nanoparticles has become a great interest to be used for several applications in many disciplines. It is possible to find biological studies taking advantage of this effect in aqueous environment. However, there exist only a few interested in tracking and controlling the local temperature profile in solid medium. Although the morphology and crystallinity of polymers can be governed, in situ, via altering the heat released from photoexcitation of metal nanoparticles. In this work, remote actuation of metal, in particular gold and silver, nanoparticles is aimed to be investigated. The local temperature change due to photothermal heating of gold nanoparticles in poly (ethylene oxide) was followed with using fluorescence probes as thermal sensors. On the other hand, a method is proposed to study Raman crystallinity as a function of temperature using the conformational changes in poly (ethylene oxide). Gold nanoparticles are heated by photothermal effect to actuate magnetite doped poly (DL-lactide-co-glycolide); which is a shape memory polymer, and multi stages of shape memory schemes were successfully achieved. At the same time, the influence of gold and silver nanoparticles (at diameter of 10 and 30 nm) on thermal and mechanical properties of polymers was studied. The mechanical properties of poly (ethylene oxide) were found to be enhanced with addition of nanoparticles regardless of the nanoparticle type and size. However, the increase in stiffness and strength of poly (ethylene oxide) reached a plateau above a certain concentration, which is attributed to nanoparticle agglomerations. Finally, the effect of silver nanoparticles on the thermal conductivity of water, ethylene glycol and hexane was investigated. The thermal conductivity of different base fluids such as hexane and ethylene glycol was found to increase upon addition of silver nanoparticles whereas, the results for water measurements was contradictory. Although, this result can be correlated with interfacial thermal resistance and viscosity of the nanofluid, the deterioration in thermal conductivity of water cannot be fully explained.