Preparation of preforms by interfacial gel polymerization method
Polimery 2005, No 5, 346
A method of preparation of poly(methyl methacrylate) (PMMA) preforms, showing gradient distribution of refractive index difference (Δn), in interfacial gel polymerization of methyl methacrylate (MMA) was elaborated. The effects of: radical initiator type [2,2'-azobisisobutyronitrile (AIBN) or benzoyl peroxide (NB)], its amount (0.001 or 0.002 mol/dm3), amount of chain transfer agent (dodecyl mercaptan - MD, 0.01-0.03 mol/dm3) as well as amount of bromonaphthalene (BN, 5-24 wt. %, being unreactive additive showing higher refractive index than polymer matrix, on the character of the curves illustrating Δn courses in the preforms were investigated. It has been found that the preforms showing Dn courses nearly ideal were obtained when BN concentration was 17 wt. % and AIBN was used as an initiator. Mutual ratio of AIBN and MD concentrations allowing eliminating the bubbles' forming in the preform has been determined. These preforms can be used as precursors for gradient-index polymer optical fibers.
Key words: interfacial gel polymerization, refractive index, gradient distribution, poly(methyl methacrylate) preform, bromonaphthalene addition, gradient-index polymer optical fibers
A.Preparation of preforms by interfacial gel polymerization method