Synthesis of a Zero-Birefringence Polymer Doped with an Inorganic Birefringent Crystal
Birefringence induced by the orientation of polymer main chains during injectionmoulding or extrusion processing restricts the application of optical polymers to optical devices that require the polarization state of incident light to be maintained. To compensate this birefringence of polymers we propose using the “birefringent crystal dopant method” - homogeneous doping with an opposite birefringent needle-like crystal. Strontium carbonate (SrCO3) was selected for this purpose and synthesized, with a length of about 200nm and a width of about 20nm. SrCO3 was doped into poly(MMA/BzMA= 78/22(wt./wt.)) film. The film was uniaxially drawn at 130°C and 4mm/min. For the first time, the positive birefringence of the drawn copolymer film at a wavelength of 633nm was compensated by doping with 0.3wt.% of SrCO3 without loss of transparency and thermostability.
Witold Lojkowski and John R. Blizzard
H. Ohkita et al., "Synthesis of a Zero-Birefringence Polymer Doped with an Inorganic Birefringent Crystal", Solid State Phenomena, Vols. 99-100, pp. 143-148, 2004