Optical assembly and method of forming an optical assembly

A method of forming an optical assembly comprising an optical device and a composition comprising a resin-linear organosiloxane block copolymer, said method comprising the step of combining the optical device and the composition to form the optical assembly, wherein the resin-linear organosiloxane block copolymer has a weight average molecular weight of at least 20,000 g/mole and comprises:

• 40 to 90 mole percent disiloxy units of the formula [R12SiO2/2] arranged in linear blocks each having an average of from 10 to 400 disiloxy units [R12SiO2/2] per linear block;
• 10 to 60 mole percent trisiloxy units of the formula [R2SiO3/2] arranged in non-linear blocks each having a weight average molecular weight of at least 500/mol;
• and
• 0.5 to 25 mole percent silanol groups;
• wherein R1 is independently a C1 to C30 hydrocarbyl and R2 is independently a C1 to C20 hydrocarbyl,
• wherein at least 30 weight percent of the non-linear blocks are crosslinked with another non-linear block and aggregated in nano-domains and
• wherein each linear block is linked to at least one non-linear block.