Refractive index changes in polyacrylates bearing alkyl sulfur groups through the sulfur oxidation reaction

Four polyacrylates with sulfur-containing side chains were prepared to examine the changes in refractive index (RI) induced by sulfur oxidation. Linear alkyl sulfides and alicyclic sulfides, such as 1,3-dithiolane and 1,4-dithiane, were introduced to impart large RIs to polyacrylates. Oxidation of the sulfur polymers by O3 and m-chloroperoxybenzoic acid led to the formation of the corresponding sulfoxide and sulfone polymers, respectively. Sulfur oxidation occurred completely, which was highlighted by the oxidized polymer exhibiting a refractive index comparable to a polymer that was synthesized using a sulfone monomer. The RI of the linear sulfur polymer increased and decreased due to the formation of sulfoxide and sulfone polymers, respectively. The Abbe number of the polymer with a linear sulfide side chain was 33.4, which increased to 48.7 after oxidation.