| 摘要: | 本研究以二階段法合成均一粒徑之次微米球，來改善傳統溶脹法於溶脹程序添加助溶脹劑、共溶劑及手續繁雜使其反應時間較長的問題。首先以低分子量PSt 為種子，探討縮短傳統溶脹程序之可行性。之後以高分子量之PSt 或PMMA為種子，探討製備出較大粒徑之均一粒徑次微米球的可行性。最後，於PSt 或 PMMA 核心反應轉化率80%~90%時添加第二階段單體的方式，探討製備出較大粒徑之均一粒徑次微米球的可行性。
結果顯示，當鏈轉移劑添加於核心轉化率55%及95%添加時，可成功製備
出粒徑為469nm 及473nm 低分子量之均一粒徑粒子。而在溶脹程序時，當添加 SDS 作為穩定劑時，由於短分子鏈段的關係造成許多小粒子，而改以PVA 為穩定劑則可以改善其狀況，並於添加量為0.7%~2%時，得到粒徑大約為825nm 之均一粒徑次微米球。
另一部分，以高分子量之PSt 或PMMA 為種子，並將溶脹溫度上升接近核
心之Tg，藉此在不需鏈轉移劑及穩定劑的情況下，成功製備出PSt 粒徑範圍為 240nm~375nm 及PMMA 粒徑範圍為316nm~462nm 之均一粒徑次微米球。
為了更進一步縮短反應時間，於PSt 或PMMA 轉化率為80%~90%時，添加
二階段單體，探討核心克數及殼層單體添加量對粒子之影響，結果隨著核心(10g~25g)及殼層單體添加量(1 倍~9 倍)上升，粒徑有明顯上升的趨勢，成功製備出PSt 粒徑範圍為208nm~420nm、PMMA 粒徑範圍為275nm~560nm 及 PMMA/PSt 粒徑範圍為402nm~582nm 之均一粒徑次微米球。改變殼層結構方面，在殼層添加20% EGDMA 交聯劑的情況下，當殼層添加倍率為6 倍以上時，即具有耐溶劑之性質。而隨著二階段單體親水性越強，則因二次成核的關係，粒子均一度越差，然而可以三階段添加親水性單體的方式，成功製備出具不同表面官能基之均一粒徑次微米球。;The size of monodisperse submicrospheres has been increased by using two-step method. Low or regular molecular weight of monodisperse seeds were prepared at the first step. Monomers were added in the seed latex and polymerized at the second step. On the other hands, in order to further shorten the reaction time, monomers were added when the seed conversion was 80% to 90%. The effect of monomer content and monomer species at two steps were also discussed.
The results indicated that low molecular weight and monodisperse PSt seed with diameter 469nm and 473nm were prepared by adding chain transfer agent at seed conversion 55% and 95%, respectively. The monodisperse PSt submicrospheres with 825 nm diameter were obtained when 0.7% to 2% of PVA were added at the second step.
The size of regular molecular weight of PSt and PMMA monodisperse seeds were 240nm and 316 nm, respectively. Using above seeds and monomers at the second step, the size of PSt and PMMA monodisperse submicrospheres became
375nm and 462nm, respectively. In addition, the reaction temperature was closed to Tg of seeds and chain transfer agent and stabilizer were not added.
To further reduce the total reaction time, monomers were added when the conversion of PSt or PMMA seed was 80% to 90%. The particle diameters of monodisperse submicrospheres were increased with increasing monomer amount at the first step (10g~25g) and with increasing monomers added at the second step (1~9) times, based on the first step monomer). The sizes of PSt, PMMA, and PMMA/PSt monodisperse submicrospheres were 420 nm, 560 nm and 582 nm, respectively. And the sizes of above seeds were 208 nm, 275 nm, and 402 nm respectively. In addition,
the monodisperse PSt submicrosphere with solvent resistant was obtained when more than 6 times of monomers and 20 wt.% of crosslinkers, EGDMA, were added at the second step. The PSt monodisperse submicrospheres with different hydrophilic functional group were also obtained by adding hydrophilic monomer at the third step. |
