The Preparation of Monodisperse Polymeric Microspheres with Crosslinking Structure by Swelling Methods

• Main Authors: Jonq-Shian Lee, 李仲軒
• Other Authors: Hui Chen
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/43866705080679072721

碩士 === 國立中央大學 === 化學工程研究所 === 87 === In this work, monodisperse compacting or crosslinking structure miscrospheres were prepared via multi-step swelling method, i.e., PS microspheres with particle size of 600nm were prepared firstly by emulsifier-free emulsion polymerization and thus followed by seeded swelling processes to produce monosize seed microspheres of 2.5μm. Accordingly, monodisperse compacting or even crosslinking structure microspheres with particle size over 3μm could thus be prepared by successively seeded swelling treatments. The preparation of seed particles of 2.5μm can be divided into two categories. Adding initiator only in the swelling agent could obtain PS particles with lower level of initiator content; whereas, adding initiator both in the swelling agent and monomer could obtain PS particles with higher level of initiator content. Monodispere crosslinking structure microspheres are obtained by swelling 2.5μm PS particle using a mixture of monomer、crosslinker (divinylbenzene)and nonsolvent (n-hexane) Consequently, when the PS seeded microspheres of 2.5μm with lower level of initiator content have been swollen directly by monomer could result in caving of microspheres and arising of secondary particles after polymerization. However, to use the seeded microspheres with higher level of initiator content and add BPO with the conc. up to 0.64wt% for the seeded swelling could completely smooth away both the caving of microspheres and the arising of secondary particles. Moreover, the uniformity of crosslinking structure microspheres could greatly be improved by adding of PVA (0.5~1.0wt%) to function as the stabilizer for the system. Besides, the experiment results showed that the surface area of porous microspheres increased with increasing of either DVB (15~45wt%) or n-hexane (0~50wt%) addition for the seeded swelling.