異丙基丙烯醯胺與疏水性單體之多孔水膠之製備與性質研究

STUDIES ON PREPARATION AND PROPERTIES OF NIPAAm/HYDROPHOBIC MONOMER POROUS HYDROGEL

葉又誠(Yu-chen Yeh)

指導教授 ： 李文福

大同大學/工程學院/化學工程學系所/碩士(2004年)

摘要

本文第一部分主要在研究兩種不同組成的異丙基丙烯醯胺(N-isopropylacrylamide)(NIPAAm)和疏水性單體含氟單體(2,2,3,3,4,4,5,5-octafluoro pentyl methacrylate)(OFPMA)以及NIPAAm和n-butyl methacrylate(BMA)共聚合之膠體及其性質之探討。結果顯示，共聚合水膠內的疏水性單體含量愈高時，膨潤度和藥物釋放量愈低,而機械強度愈高。在收縮動力行為方面，當水膠內的疏水性單體含量愈高,膠體愈快收縮，使得水膠內部的水愈不易被排出。快速膨潤收縮實驗方面，當水膠內疏水性的含量愈高，則愈快達平衡。而LCST的差異則不明顯。比較不同的疏水性單體可發現，由於含氟單體的疏水性較高,其共聚合水膠的膨潤度和藥物釋放量較小,機械強度較強。
本文第二部分主要在研究添加有機(PEG8000)或無機(CaCO3)的成孔劑來製備多孔水膠(porous hydrogel)。結果顯示添加PEG8000的水膠有較高的膨潤度有較高的膨潤度和藥物釋放量，但是機械強度較弱。收縮動力和快速膨潤收縮方面，兩者之間沒有明顯的差異，但是和未成孔的水膠相比，多孔性水膠可以排出較多的水，並且達平衡的速度較快。這些都是因為PEG8000有較高的分子量及鏈長,可形成較多互穿的孔洞。在SEM裡也可以看出添加PEG8000的水膠有較多較大的孔洞。
本文第三部分主要在研究以不同聚合溫度形成多孔水膠。由於PNIPAAm應答速率緩慢, 所以希望藉由製作多孔結構以提升應答速率，而本實驗使用的方法為改變聚合時的溫度以達到多孔結構。一是低溫(-18℃)，稱為冷凍法；另一為高溫(45℃)，稱為相分離法。結果顯示，不論是冷凍法或是相分離法均能大幅提升吸水和排水速率以及咖啡因釋放量，但是也大幅降低了膠體強度。在快速膨潤收縮行為方面，由此兩種成孔法製備之水膠均能在短時間內吸入或排出較大量的水。比較兩種方法時的可發現，冷凍法的效果更加。這是因為由冷凍法製備的水膠具有許多互穿的大孔洞,而相分離法則是很多的小孔洞,。從SEM照片上也可發現此現象。

關鍵字

異丙基丙烯醯胺 ； 水膠 ； 含氟單體

並列摘要

A series of thermoreversible copolymeric hydrogels were prepared from various molar ratios of N-isopropylacrylamide (NIPAAm) and hydrophobic monomers such as 2, 2, 3, 3, 4, 4, 5, 5-Octafluoropentyl methacrylate (OFPMA). and n-butyl methacrylate (BMA). The effect of hydrophobic monomer on the swelling behavior, mechanical property on the present copolymeric hydrogels was investigated. Results showed that the swelling ratios and critical gel transition temperature (CGTT) decreased with an increase of the content of hydrophobic monomers. The gel strengths’ increased with an increase of the content of hydrophobic monomers. Because of the stronger hydrophobivity of OFPMA, the NIPAAm/OFPMA copolymeric hydrogels had smaller swelling ratios. On the other hand, because of fluorine atom was larger than hydrogen atom, the NIPAAm/OFPMA copolymeric hydrogels had larger gel strengths’ under the same crosslinker content.
A series of porous hydrogels were prepared by adding CaCO3 or poly (ethylene glycol)8000 as porosigen to form porous structure.. The results showed that after adding the porosigen, the gels took less time to swell to equilibrium than the gels without adding porosigen. But there was no significant difference in swelling behavior and shear modulus between adding CaCO3 and PEG8000. Both two gels could improve deswelling rate and reached equilibrium more quickly in fast swelling-deswelling behavior. Compared to two different gels, the gels that added PEG8000 also had higher caffeine release amount. This was because PEG8000 had higher molecular and longer chain length. So the gels that added PEG8000 could form more interpenetrated pores. From SEM photographs we could also find this phenomena.
Poly(NIPAAm) had disadvantage of slower swelling and deswelling rate. In order to improve swelling and deswelling rate, we made the gels porous. We changed the temperature of polymerization process. We let monomer solution stayed in 25℃ for a short time, then transferred the gel to relative low temperature (-18℃)or high temperature (45℃) for 24hrs. We called them freezing method (-18℃)and phase separation method (45℃), respectively. The results showed that these two methods improved swelling and deswelling rate. The swelling rate was 10 times than the conventional hydrogels. The deswelling rate was 3~5 times than conventional hydrogels. This was because these two methods made the gels have macroporous structure. The main reason why the gels could swell and deswell fast is that there were many capillary channels in the gels. From SEM photographs we could find that the pores made by freezing method were lager than phase separation method.

並列關鍵字

hydrogel ； NIPAAm ； perfluoroalkyl methacrylate

參考文獻

1. Hoffman, A. S. J Control Release 1987, 6, 297.

2. Bae, Y. H.; Okano, T.; Kim, S. W. J Polym Sci, Polym Phys 1990, 28, 923.

3. Hirokawa, E.; Tanaka, T. J Chem Phys 1984, 81, 6379.

4. Ricka, J.; Tanaka, T. Macromolecules 1984, 17, 2916.

5. Eisenberg, S. R.; Grodzinski, A. J. J Membr Sci 1984, 19, 173.