Polyacrylates have become the preferred materials for optical applications replacing the conventionally used glass due to their superior optical clarity. The major disadvantage with polyacrylates is their low (1.40–1.50) refractive index besides their poor impact resistance. The improvements in refractive index as well as mechanical properties can be achieved by way of incorporation of metals or metal compounds in the matrix. A novel methodology for the incorporation of high refractive index metals into low refractive index polymeric materials to improve the refractive index and impact resistance of the latter has been developed. With the in-situ formation of nanoparticles of , the refractive index of polyacrylates improved from 1.45 to 1.53 and the Abbe number increased from 40 to 57. One of the interesting dimension of this study pertains to the possibility of tailor-making of the two key optical properties of materials by way of varying the amount of being formed in-situ. Thermal stability and impact resistance of nano dispersed (4.3% by wt. of Ti) polyacrylates are found to be better than the neat polyacrylates. Moreover, -containing polyacrylate is of light weight. TEM, SEM, and IR analysis confirms the in-situ formation of nanoparticles of . Gamma irradiation has been used as an eco-friendly technique for polymerization. The developed compositions can be cast polymerized into clear and bubble free material for optical applications. 1. Introduction Amongst the conventional materials used for optical applications, glass has been the most popular and till recently considered as the preferred candidate material. Glass, besides being a brittle and heavy material, is also prone to scratches. Plastics with optical properties as good as glass, if not better, have been found to be a better material than glass for various optical applications [1–7]. Apart from being light weight, optical plastics exhibit optical properties like refractive index, Abbe number, and transmittance superior to glass. These days, it has become possible to maneuver all of these properties by designing suitable optical plastics. However, it has been a challenge to manufacture optical plastics with high refractive index and high Abbe number. The other big challenge pertaining to the development of optical plastics concerns the tailor-making of properties. It has not been possible so far to have chemistries that can produce materials of varying properties as per requirements. For this, composite materials in devices such as lenses, coatings and filters are being extensively studied
References
[1]
M. Tyagi, M. Verma, G. Seshadri, A. Malik, S. Agarwal, and R. K. Khandal, “Development of metal containing polymers for optical application,” Journal of Polymer Materials, vol. 23, no. 1, pp. 21–28, 2006.
[2]
H. Dislich, “Plastics as optical materials,” Angewandte Chemie International Edition, vol. 18, no. 1, pp. 49–59, 1979.
[3]
M. Tyagi, G. S. Jha, G. Seshadri, A. Malik, S. Aggarwal, and R. K. Khandal, “Metal containing polymers for optical applications; part II,” Journal of Polymer Materials, vol. 24, no. 2, pp. 135–148, 2007.
[4]
J. D. Lytle, Handbook of Optics, McGraw Hill, New York, NY, USA, 2nd edition, 1995.
[5]
W. F. Frank, “Precision plastics optics for optical storage,” in Precision Plastic Optics for Optical Storage, Displays, Imaging, and Communications, vol. 3135 of Proceedings of the SPIE, pp. 169–178, July 1997.
[6]
M. Verma, G. S. Jha, G. Seshadri, and R. K. Khandal, “Optical plastics—a wonder material,” Journal of the Indian Chemical Society, vol. 82, no. 12, pp. 1113–1118, 2005.
[7]
G. S. Jha, G. Seshadri, A. Mohan, and R. K. Khandal, “Development of high refractive index plastics,” e-polymers, no. 120, pp. 1–25, 2007.
[8]
G. Philipp and H. Schmidt, “New materials for contact lenses prepared from Si- and Ti-alkoxides by the sol-gel process,” Journal of Non-Crystalline Solids, vol. 63, no. 1-2, pp. 283–292, 1984.
[9]
B. Wang, G. L. Wilkes, J. C. Hedrick, S. C. Liptak, and J. E. McGrath, “New high refractive index organic/inorganic hybrid materials from sol-gel processing,” Macromolecules, vol. 24, no. 11, pp. 3449–3450, 1991.
[10]
F. Papadimitrakopoulos, P. Wisniecki, and D. E. Bhagwagar, “Mechanically attrited silicon for high refractive index nanocomposites,” Chemistry of Materials, vol. 9, no. 12, pp. 2928–2933, 1997.
[11]
A. Ershad-Langroudi, C. Mai, G. Vigier, and R. Vassoille, “Hydrophobic hybrid inorganic-organic thin film prepared by sol-gel process for glass protection and strengthening applications,” Journal of Applied Polymer Science, vol. 65, no. 12, pp. 2387–2393, 1997.
[12]
W. C. Chen, S. J. Lee, L. H. Lee, and J. L. Lin, “Synthesis and characterization of trialkoxysilane-capped poly(methyl methacrylate)-titania hybrid optical thin films,” Journal of Materials Chemistry, vol. 9, no. 12, pp. 2999–3004, 1999.
[13]
H. A. Hornak, Polymers for Lightwave and Integrated Optics, Marcel Dekker, New York, NY, USA, 1992.
[14]
“American Standard Test Method for Index of Refraction of Transparent Organic Plastics ASTM D-542,” 2009.
[15]
“American Standard Test Method for density and specific gravity (Relative density) of plastics by displacement ASTM D-792-00,” 1995.
[16]
A. Leaustic, F. Babonneau, and J. Livage, “Structural investigation of the hydrolysis-condensation process of titanium alkoxides modified by acetylacetone. 1. Study of the alkoxide modification,” Chemistry of Materials, vol. 1, no. 2, pp. 240–247, 1989.
