![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
Interferometric measurements of the effect of a polymer gradativelly added in a lyotropic liquid crystal is reported here. Studies of the phase diagram, birefringence and critical exponents as a function of the polymer concentration are presented. Measurements of the optical birefringence as a function of temperature are performed with the micellar system potassium laurate, 1-decanol, and water doped with variable quantities of the polymer poly-ethylene-glycol (PEG). The transitions from the calamitic nematic phase to a reentrant discotic-biaxial-discotic phase were observed when increasing the PEG molar concentration. Our results confirm the critical properties of the uniaxial-to-biaxial nematic transition. The critical exponent for the order parameter (β = 0.38) obtained for the sample without PEG is in god agreement with the value caculated for the XY model. Some results with higher PEG doping concentration indicate that β is higher than 0.38 leading to the mean-field value.