Executive Summary : | The global warming due to green house emissions has increased the temperature of the world and requires surplus energy in order to control the temperature in buildings and automotive. Particularly, Near Infrared (NIR) radiation is the major source of heating in solar radiation. Thus, there is a huge demand to develop self-responsive materials to shield NIR radiation emitting from sun light for savings in energy consumption utilized for refrigeration and air conditioners and heat insulation. Usually, laminated glasses or transparent rigid plastics coated with NIR shielding materials are used as automotive windows in cars and buildings to control transmittance of visible light and shield NIR light to keep the room cool. In last decades, electrochromic, photochromic and thermochromic smart windows are developed but these systems are expensive because of extra power consumption for supporting components and their maintenance. On contrary, thermo-responsive polymers like poly-N-Isopropyl acrylamide (PNIPAM) and poly-N-Vinylcaprolactum (PNVCL) based smart windows are low cost materials with no need of any additional power supply system. The responsive copolymer undergoes phase transformation from optical transparent to opaque with change in temperature. However, there is huge risk of maintenance issues related to leakage of liquid, breakage possibility and stability of the solution, etc. So there is a need of mechanically strong and flexible hydrogel film which can be rolled off like a smart curtain with thermos-responsive and NIR shielding capability. Further, use of relatively green and sustainable bio-based polymeric materials are the needs of the hour to make it industrially viable and eco-friendly. In the proposed work, greener and sustainable composite hydrogel using pNIPAM or PNVCL grafted with bio-sourced polymers (acrylates and silanized methyl esters of plant oil, cellulose, bio-polyurethane acrylates) and NIR absorbing nanoparticles (alkali doped WOx; WOx. Cs-WOx and Li-Cs-Wox) with visible light transmittance for energy saving building applications. NIR shielding materials based on crystal engineered tungsten nanoparticles will be prepared and incorporated in thermo-responsive composite films and optimized for desired modulation of transmittance with fast response time, maximum shielding efficiency and thermal insulation. Modified stimuli responsive PNIPAM/PNVCL polymers and copolymers with bio-monomers shall be designed and synthesized through free radical and ATRP polymerization techniques. The properties shall be evaluated and analyzed in detail along with durability. Nano-NIPAM/NVCL-biopolymer hybrid system shall be prepared using electro-spinning/casting technique and the properties shall be evaluated for desired applications. The lab scale prototypes shall be developed for practical shielding application as smart window/curtain for scale up/commercialization feasibility. |