高分子型多孔薄膜因操作簡便且成本低廉，而被應用於膜分離程序，但在嚴酷的環境下，例如高溫，有機溶劑的系統中，薄膜常會裂解或崩壞導致分離失敗，從而限制了高分子薄膜的應用範疇。新穎之主鏈聚氧代氮代苯并環己烷(PBz-Oda)高分子帶有雙氮氧雜環官能基，其熱致交聯後的網狀結構提升了熱穩定性，耐有機溶劑性以及機械強度;此外，交聯後的PBz-Oda因為高分子鏈間誘發分子內氫鍵的生成，具有極低的表面能而提升疏水性，可應用於有機溶劑系統的分離。本研究透過靜電紡絲法以及蒸氣誘導相轉換法，尋求製備PBz-Oda高分子的多孔性薄膜，並探討製程參數對薄膜孔洞的構型以及膜孔大小的影響。首先針對溶液做討論，以較低濃度的電紡液所製得的電紡纖維其纖維直徑較細，所以纏繞更為緊密，編織成孔洞較小的薄膜;而若欲製成孔洞較小的相轉換薄膜，則需要黏度較高的鑄膜液。另藉由溶解度參數表可以預測膜孔構型，若溶劑與非溶劑之間的互溶性越好，可以得到較高孔隙率的薄膜，並從上述兩參數挑選出最適化的條件則可獲得奈米孔洞且同時具備高孔隙率的蕾絲結構薄膜。將此薄膜用於油水分離後，其純溶劑通量相當高，同時在分離甲苯和水的乳化溶液時，也有相當高的通量，以及分離效率。

Porous polymer membranes have been widely used in membrane separation due to its low cost and facile operation. However, membranes would degrade or crack in harsh environment such as high temperature and organic solvent system. It may lead to separation failure which critically limit the application of polymeric membranes. A novel main chain type polybenzoxazine processes thermally induced crosslink reaction and the obtained polymer network thus enhances thermal stability, solvent resistance and mechanical properties. Besides, crosslinked polybenzoxazine possesses extremely low surface free energy which results from the formation of intramolecular hydrogen bonds. Hydrophobicity of materials rises so that the application can be broadened to separation for organic solvent system. In this study, polybenzoxazine is fabricated into porous membranes via vapor induce phase separation (VIPS) and electrospun technique. The variation of morphology and pore size are discussed under different circumstances. Solution condition is discussed firstly. Generally speaking, the lower electrospinning solution is, the smaller fiber size membrane will be obtained. Meanwhile, the pore size is also smaller because of tighter entanglement. On the other hand, if the smaller pore size is desired in phase separation membranes, the more viscous solution is required. Besides, the morphology of pores can be predicted by referring to solubility parameters chart. The membrane of higher porosity will be produced if the miscibility of solvent and non-solvent is introduced. Within these two parameters, the optimal condition is determined to fabricate inter-connective so-called lacy structure which owns high porosity and small pore size. The as-prepared membranes show relatively high flux in pure solvent. The efficiency and permeation are also excellent in water-in-toluene emulsion separation.

1. Marchetti, P.; Solomon, M. F. J.; Szekely, G.; Livingston, A.G. Molecular Separation with Organic Solvent Nanofiltration: A Critical Review. Chem. Rev. 2014, 114, 10735-10806
2. Guillen, G. R.; Pan, Y. J.; Li, M. H.; Hoek, E. M. V. Preparation and Characterization of Membranes Formed by Nonsolvent Induced Phase Separation: A Review. Ind. Eng. Chem. Res. 2011, 50, 3798-3817
3. Wang, D. M.; Lai, J. Y. Recent advances in preparation and morphology control of polymeric membranes formed by nonsolvent induced phase separation. Curr. Opin. Chem. Eng. 2013, 2, 229-237
4. Tsai, J. T.; Su, Y. S.; Wang, D. M.; Kuo, J. L.; Lai, J. Y.; Deratani, A. Retainment of pore connectivity in membranes prepared with vapor-induced phase separation. J. Membr. Sci. 2010. 362. 360-373.
5. Evenepoel, N.; Wen, S.; Tilahun Tsehaye, M.; Van der Bruggen, B. Potential of DMSO as greener solvent for PES ultra- and nanofiltration membrane preparation. J. Appl. Polym. Sci. 2018. 135. 46494.
6. Musale, D. A.; Kumar, A.; Pleizier, G. Formation and characterization of poly(acrylonitile)/Chitosan composite ultrafiltration membranes. J. Membr. Sci. 1999. 154. 163-173.
7. Scharnagl, N.; Buschatz, H. Polyacrylonitrile (PAN) membranes for ultra- and microfiltration. Desalination. 2001. 139. 191-198.
8. Kim, I. C.; Yun, H. G.; Lee, K. H. Preparation of asymmetric polyacrylonitrile membrane with small pore size by phase inversion and post-treatment process. J. Membr. Sci. 2002. 199. 75-84.
9. Zhang, G.; Meng, H.; Ji, S. Hydrolysis differences of polyacylonitrile support membrane and its influences on polyacrylonitrile-based membrane performance. Desalination. 2009. 242. 313-324.
10. Zhu, T.; Luo, Y.; Lin, Y.; Li, Q.; Yu, P.; Zeng, M. Study of pervaporation for dehydration of caprolactam through blend NaAlg-poly(vinyl pyrrolidone) membranes on PAN supports. Sep. Purif. Technol. 2010. 74. 242-252.
11. Van de Witte, P.; Dijkstra, P. J.; Van den Berg, J. W.A.; Feijen, J. Phase separation processes in polymer solutions in relation to membrane formation. J. Membr. Sci. 1996. 117. 1-31.
12. Tiraferri, A.; Yip, N. Y.; Phillip, W. A.; Schiffman, J.D.; Elimelech, M. Relating performance of thin-film composite forward osmosis membranes to support layer formation and structure. J. Membr. Sci. 2011. 367. 340-352.
13. Khayet, M.; Matsuura, T. Preparation and characterization of polyvinylidene fluoride membranes for membrane distillation. Ind. Eng. Chem. Res. 2001. 40. 5710-5718.
14. Fontananova, E.; Jansen, J. C.; Cristiano, A.; Curcio, E.; Drioli, E. Effect of additives in the casting solution on the formation of PVDF membranes. Desalination. 2006. 192. 190-197.
15. Su, C. I.; Shih, J. H.; Huang, M. S.; Wang, C. M.; Shih, W. C.; Liu, Y. S. A study of hydrophobic electrospun membrane applied in seawater desalination by membrane distillation. Fibers and Polymers. 2012. 13. 698-702
16. Fuertes, A.B.; Nevskaia, D.M.; Centeno, T.A. Carbon composite membranes from Matrimid® and Kapton® polyimides for gas separation. Microporous Mesoporous Mater. 1999. 33. 115-125
17. Clausi, D. T.; Koros, W. J. Formation of defect-free polyimide hollow fiber membranes for gas separations. J. Membr. Sci. 2000 167. 79-89
18. Wei, C.; Cheng, Q.; Lin, L.; He, Z.; Huang, K.; Ma, S.; Chen, L. One-step fabrication of recyclable polyimide nanofiltration membranes with high selectivity and performance stability by a phase inversion-based process. J. Mater. Sci. 2018. 53. 11104-11115
19. Zaman, N. K.; Rohani, R.; Mohammad, A. W.; Isloor, A. M. Polyimide-graphene oxide nanofiltration membrane: Characterizations and application in enhanced high concentration salt removal. Chem. Eng. Sci. 2018. 177. 218-233
20. Park, H. C.; Kim, Y. P.; Kim, H. Y.; Kang, Y. S. Membrane formation by water vapor induced phase inversion. J. Membr. Sci. 1999. 156. 169-178
21. Ahmed, F. E.; Lalia, B. S.; Hashaikeh, R. A review on electrospinning for membrane fabrication: challenges and applications. Desalination. 2015. 356. 15-30
22. Ishino, C.; Okumura, K. Wetting transitions on textured hydrophilic surfaces. The European Physical Journal E. 2008. 25. 415-424
23. Tijing, L. D.; Choi, J. S.; Lee, S.; Kim, S. H.; Shon, H. K. Recent progress of membrane distillation using electrospun nanofibrous membrane. J. Membr. Sci. 2014. 453. 435-462
24. Wang, R.; Liu, Y.; Li, B.; Hsiao, B. S.; Chu, B. Electrospun nanofibrous membranes for high flux microfiltration. J. Membr. Sci. 2012. 392. 167-174
25. Holly, F. W.; Cope, A. C. Condensation products of aldehydes and ketones with o-aminobenzyl alcohol and o-hydroxybenzylamine. J. Am. Chem. Soc. 1944. 66. 1875-1879
26. Ishida, H.; Rodriguez, Y. Catalyzing the curing reaction of a new benzoxazine‐based phenolic resin. J. Appl. Polym. Sci. 1995. 58. 1751-1760
27. Kasapoglu, F.; Cianga, I.; Yagci, Y.; Takeichi, T. Photoinitiated cationic polymerization of monofunctional benzoxazine. J. Polym. Sci., Part A: Polym. Chem. 2003. 41. 3320-3328
28. Yagci, Y. Photoinitiated Cationic Polymerization of Unconventional Monomers Macromol. Symp. 2006. 240. 93-101
29. Ning, X.; Ishida, H. Phenolic materials via ring‐opening polymerization: Synthesis and characterization of bisphenol‐A based benzoxazines and their polymers. J. Polym. Sci., Part A: Polym. Chem. 1994. 32. 1121-1129
30. Ishida, H.; Rodriguez, Y. Curing kinetics of a new benzoxazine-based phenolic resin by differential scanning calorimetry. Polymer. 1995. 36. 3151-3158
31. Wang, C. F.; Su, Y. C.; Kuo, S. W.; Huang, C. F.; Sheen, Y. C.; Chang, F. C. Low‐Surface‐Free‐Energy Materials Based on Polybenzoxazines. Angew. Chem. Int. Ed. 2006. 45. 2248-2251. DOI: 10.1002/anie.200503957
32. Lin, C. H.; Chang, S. L.; Shen, T. Y.; Shih, Y. S.; Lin, H. T.; Wang, C. F. Flexible polybenzoxazine thermosets with high glass transition temperatures and low surface free energies. Polym Chem. 2012. 3. 935-945. DOI: 10.1039/C2PY00449F
33. Li, H. Y.; Lee, Y. Y.; Chang, Y.; Lin, C. H.; Liu, Y. L. Robustly Blood‐Inert and Shape‐Reproducible Electrospun Polymeric Mats. Adv. Mater. Interfaces. 2015. 2. DOI: 10.1002/admi.201500065
34. Li, H. Y.; Li, G. A.; Lee, Y. Y.; Tuan, H. Y.; Liu, Y. L. A Thermally Stable, Combustion‐Resistant, and Highly Ion‐Conductive Separator for Lithium‐Ion Batteries Based on Electrospun Fiber Mats of Crosslinked Polybenzoxazine. Energy Technol. 2016. 4. 551-557. DOI: 10.1002/ente.201500368
35. Liu, C. T.; Liu, Y. L. pH-Induced switches of the oil-and water-selectivity of crosslinked polymeric membranes for gravity-driven oil–water separation. J. Mater. Chem. A. 2016. 4. 13543-13548.
36. Zhong, M.; Su, P. K.; Lai, J. Y.; Liu, Y. L. Organic solvent-resistant and thermally stable polymeric microfiltration membranes based on crosslinked polybenzoxazine for size-selective particle separation and gravity-driven separation on oil-water emulsions. J. Membr. Sci. 2017. 550. 18-25
37. Liao, Y. L.; Hu, C. C.; Lai, J. Y.; Liu, Y. L. Crosslinked polybenzoxazine based membrane exhibiting in-situ self-promoted separation performance for pervaporation dehydration on isopropanol aqueous solutions. J. Membr. Sci. 2017. 531. 10-15
38. Liu, C. T.; Su, P. K.; Hu, C. C.; Lai, J. Y.; Liu, Y. L. Surface modification of porous substrates for oil/water separation using crosslinkable polybenzoxazine as an agent. J. Membr. Sci. 2018. 546. 100-109
39. Barton, A. F. Solubility parameters. Chem. Rev. 1975. 75. 731-753