In this study, phase separation induced by free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) and poly(methyl methacrylate) (PMMA) with various compositions in term of weight percentage was investigated. Particularly, experiments were carried out at different temperatures from 70 to 110 ºC and weight content of PMMA from 1 to 15 wt.%. The effects of these parameters on morphology and properties of the polymer blends were observed and analyzed. Optical microscopy, X-ray CT scanning were employed to observe the structure of the obtained blends. Based on the images of the obtained blends, the characteristic length and contrast value of the morphology were determined. In addition, optical transmittance characterization and thermal stability analysis of the products were performed by using UV-Vis spectrometry and thermogravimetric analysis, respectively. It was found that the optimum blend that possessed 12 wt.% PMMA content and conducted at 100 ºC allowed visual light transmittance of larger than 95 %. The results showed promising applicability of the polymer blend as an alternative for soft optically transparent materials.