A Study on the Miscibility of Selected Blends of Methyl Methacrylate−Benzyl Methacrylate Copolymers

Abstract

The blend compatibility of methyl methacrylate (MMA)−benzyl methacrylate (BzMA) copolymers with different monomer compositions has been studied to investigate their feasibility as plastic optical fibers. Copolymers with variable comonomer composition were first synthesized, and the blend compatibility between them was investigated by solution blending and melt blending. The results of 1H NMR, ellipsometry, and differential scanning calorimetry indicate that the copolymers synthesized in this study are random copolymers, with their refractive index and the glass transition temperature varying linearly with their monomer content. While the solution-blended samples indicated immiscibility between copolymers with large differences in their monomer composition, melt-blended samples indicated miscibility showing single glass transition temperature and homogeneity in scanning electron micrographs. The difference between the results of solution blends and melt blends may be attributed to the slow kinetics of phase separation and the intensive shear energy input during melt blending. These results suggest that MMA−BzMA random copolymers are appropriate materials applicable to the coextrusion method of Park and Walker (U.S. Patent 89 929 161, 1997) for the fabrication of graded-index plastic optical fibers.

Tailored Gradient Morphologies and Anisotropic Surface Patterns in Polymer Blends

“…Formation mechanisms of gradient structures can be deducted easier when the effect of breakup can be ignored . In principle, the deformation and breakup of dispersed droplets can be estimated by Taylor's theory . In his theory, the capillary number Ca is defined as the ratio of viscous forces (trying to deform the droplet) and interfacial tension (trying to preserve the shape of the droplet).…”

“…Gradient polymer blends are truly attractive materials since their particular morphology allows to develop desired properties in certain regions of the material . Such gradient structures have found elaborate applications, for instance in graded index optical fibers, where the refractive index of a polymer is controlled by the diffusion of immiscible monomer species . The impact of a gradient morphology is not necessarily limited to the bulk, but can also influence the surface properties.…”