| dc.description.abstract | Highly cross-linked and more than 6 µm monodisperse microspheres have been fabricated by two-step swelling polymerization. Polystyrene (PS) seed particle (3.30 µm and Cv 2.50 %) was prepared by dispersion polymerization.
At first, styrene (St) or methyl methacrylate (MMA) were added in the PS solution to investigate whether monodisperse PS/PS and PS/PMMA were prepared or not. The result showed only monodisperse PS/PMMA could be prepared in the two-step polymerization. The monodisperse 6.67 μm PS/PMMA microsphere could be prepared by adding 5.0 wt% stabilizer (polyvinyl alcohol; PVA), 1.0 wt% initiator (benzoyl peroxide; BPO), 0.1 g swelling agent (cyclohexane), 0.2 g inhibitor (NaNO2) and 8 g monomer (MMA) in the 0.1 g PS seed solution.
Then the effects of amount of PVA, BPO, cyclohexane, NaNO2, MMA and ethylene glycol dimethylacrylate (EGDMA) on the particle size, particle size distribution, solvent resistance, and thermal stability of PS/P(MMA-co-EGDMA) microsphere were discussed.
The results showed that the monodisperse PS/P(MMA-co-EGDMA) microsphere could be obtained by adding suitable amount of PVA (2.5 wt%), cyclohexane (0 or 0.1g), and NaNO2 (0.2 g) in 0.1 g PS seed solution. And these microspheres had uniform shape when the weight fraction of BPO was increased to 1.5 wt%.
When the weight fraction of EGDMA was fixed to 20 wt%, with increasing total amount of MMA and EGDMA, the particle size was increased. PS/P(MMA-co-EGDMA) monodisperse microsphere with 7.07 µm size was obtained by adding 5 g total amount of MMA and EGDMA. On the other hand, when the total amount of MMA and EGDMA was fixed to 6 g, with increasing the weight fraction of EGDMA, the particle size was increased. The PS/P(MMA-co-EGDMA) monodisperse microsphere with 9.48 µm was prepared by adding 50 wt% EGDMA.
The PS/P(MMA-co-EGDMA) particles with more 20 wt% EGDMA had excellent performance on solvent resistance. TGA results showed PS/P(MMA-co-EGDMA) suppressed the thermal stability of PS. So, introducing MMA or EGDMA to the system decreased the thermal stability of PS. But the temperature of 10 wt% loss (Td10) for PS/P(MMA-co-EGDMA) is 255 ℃, above the processing temperature. | en_US |