Cross-linked polymer microspheres are widely used in biomedicine, flat panel display, analytical testing, in vitro diagnostics, semiconductor chips, and light diffusion. However, the process of preparing micron-sized cross-linked polymer microspheres is complicated, and it is difficult to obtain a high crosslinking degree conveniently. In this work, we applied post-crosslinking strategy to prepare poly (methyl methacrylate) (PMMA) microspheres having a high crosslinking degree by dispersion polymerization, while the method separated the polymerization process and cross-linking process of microspheres. In the method, the silane coupling agents containing double bonds were used as the comonomer in polymerization and hydrolyzed to form Si–O–Si cross-linked structure at the later stage. The obtained microspheres are not only highly cross-linked but also have uniform particle size distribution and good thermal stability. The produced cross-linked PMMA microspheres exhibit great light diffusion properties and might be employed as a light diffusion agent in a polycarbonate matrix. Graphical Abstract We prepared the cross-linked PMMA microspheres by post-crosslinking method and mixed the cross-linked PMMA microspheres with the matrix PC to obtain the light diffusers.
Cross-linked poly(methyl methacrylate) (PMMA) microspheres have been successfully prepared by using the asymmetric cross-linker allyl methacrylate (AMA) via dispersion polymerization. The influence of the AMA amount and polymerization process on the PMMA particle size and morphology has been studied thoroughly. It was found that micron-sized, cross-linked PMMA particles with narrow size distributions could be obtained by a semi-continuous process with the asymmetric cross-linker AMA. The obtained micron-sized, cross-linked PMMA particles could be further used as a light diffusion agent in a polycarbonate matrix, and their light diffusion properties were significantly enhanced by increasing the gel content in the cross-linked particles. Moreover, the influence of the polymerization process, cross-linker content in PMMA and PMMA content in the polycarbonate matrix on light diffusion was carefully investigated. The results showed that the PMMA particles containing 5.0 wt% AMA, obtained by semi-continuous polymerization, had a higher haze and gel content and exhibited a better light diffusion effect than did the other particles.
We prepared cross-linked PMMA microspheres by dispersion polymerization with asymmetric cross-linker AMA and obtained light diffusers by blending cross-linked PMMA microspheres with matrix PC.
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