臺灣博碩士論文加值系統

材料的水合特性被認為與其蛋白質吸附抗性關係密切。近年之研究顯示，側鏈帶有雙離子基團之高分子，表現出優異的抗蛋白質吸附能力。其中又以poly-sulfobetaine methacrylate (poly-SBMA)為最常被探討之材料。然而目前對於水分子在材料表面抗吸附機制所扮演之角色，尚未完全釐清。本研究特別針對四種雙離子型高分子探討其水合特性，分別為：帶有亞硫酸根(SO3-)之pSBAA及帶有羧基(COO-)但離子間距不同之pCBAA1、pCBAA3及pCBAA5。研究首先針對其聚合參數效應進行探討以製備所設計之雙離子型高分子材料；並使用示差掃描熱卡量計(DSC)量測水分子與高分子鏈段之作用及水合狀態。
在高分子合成部份，實驗結果顯示，控制反應時間為6小時，隨正負離子間距增長，聚合越困難。pCBAA1和pCBAA5較適合短時間之聚合； pCBAA3則隨反應時間拉長可有效降低PDI。至於濃度效應，單體及起始劑之絕對濃度等比例提高，可使分子量及產率微幅上升；若僅提高起始劑濃度，則pCBAA1及pCBAA3隨[單體]/[ 起始劑] 比值之下降，分子量降低，然而pCBAA5則反而上升，顯示正負離子基團間距不同時，主導聚合之反應可能有所不同。實驗亦發現引入單體和起始劑的混合方式會對聚合反應造成顯著影響，以未溶解之起始劑與單體混和會有較高的轉化率。同時使用APS與SBS作為起始劑，雖可提升產率，但分子量明顯下降。使用乙醇溶液作為溶劑，同樣會造成分子量下降。
在水合性質分析方面，實驗結果觀察到所檢測之四種雙離子型高分子，隨總含水量之增加，其表面不同水合狀態之變化，具有類似特徵。所有材料中均可觀察到四種主要的水合狀態，即: nonfreezing water、free water、freezing bound water以及bulk water，其中冷結晶會伴隨free water出現，同時與freezing bound water間並無明確對應關係。進一步量化積分，可發現CB系列高分子較SB系列有更強的水合能力；拉長正負離子間距，偶極矩上升，可發現材料表面之 bound water 數量隨之增加，顯示水合能力CBAA-5> CBAA-3> CBAA-1。

Water hydration behavior of a biomaterial is believed to be closely related to its ability on protein adsorption resistance It is well known that a polymer composed of zwitterionic groups exhibits superior protein resistant property. Among them, poly-sulfobetaine methacrylate (poly-SBMA) is the most commonly studied zwitterionic antifouling material. However, it is still unclear about the role of hydrated water on the antifouling ability of the materials. Thus, in this study, we specifically selected four kinds of zwitterionic materials, i.e. poly- sulfobetaine acrylamide (pSBAA), which is with (SO3-) anionic group, and a series of poly- carboxybetaine acrylamides of pCBAA-1, pCBAA-3, and pCBAA-5, which are carrying the same carboxylic anionic group but with different space chain length between the positive and negative groups. This study first examine the effects of some polymerization parameters to obtain the predesigned zwitterionic polymers. The hydration behavior of the synthesized zwitterionic polymers were then analyzed by differential scanning calorimetry (DSC) method.
For polymer syntheses, the experimental results indicated that with reaction time of 6 hours, the polymerization is harder for zwitterionic molecules with the longer space length. pCBAA1 and pCBAA5 are more suitable for short reaction time; while prolonged reaction time can effectively decrease the polydispersity of the product of pCBAA3. As for the effects of monomer and initiator concentration, it is found that both of the conversion rate and molecular weight were slightly increased if the monomer and initiator concentration were increased proportionally. By increasing initiator concentration alone, the ratio of [monomer]/[initiator] will decrease and cause the decrease of molecular weight for pCBAA1 and pCBAA3. Nevertheless, the effect of this parameter on pCBAA5 shows an opposite tendency, i.e. the molecular weight increases instead, suggesting that the rate determining reaction for the polymerization of pCBAA5 might be different. We also found that the way of introducing reactants into the reactor will also have significant effects on the polymerization reaction. Initiator added in solid form gave the higher conversion rate. Using mixture of APS and SBS as an initiator could increase the conversion rate, while molecular weight decrease apparently though. Using ethanol, instead of water, as solvent, also causes the decrease of molecular weight.
About the hydration properties, it is found that the four zwitterionic polymers showed similar features with the increase of the total water content. Four hydration states, i.e., nonfreezable water (nf), free water (free), freezing bound water (fb), and bulk water (bulk) were identified in all four tested materials. Cold crystallization were observed in accompany with free water but showed no specific correlation with the freezing bound water. By quantitatively integrating the thermogram curves, it is found that the carboxybetain polymers showed stronger hydration ability than the sulfobentain polymers. The dipole moment of a zwitterionic group was larger for molecule with longer space length between the positively charged and negatively charged groups. It is found that the amount of bound water increased with the increase of space length, suggesting that the order of hydration ability of the CBAA series of material should follow CBAA-5> CBAA-3> CBAA-1.

目錄
摘要 I
Abstract II
目錄 IV
圖目錄 VI
第一章 簡介 1
1.1 研究背景 1
1.2 研究動機與目的 2
第二章 文獻回顧 3
2.1常見之抗吸附材料 3
2.1.1聚乙二醇(PEG)之簡介與發展 3
2.1.2雙離子型高分子之簡介與發展 4
2.2 材料表面抗吸附之機制 7
2.2.1 抗吸附之理論模型 8
2.2.2 影響材料表面抗吸附之參數 10
2.3 水合作用與抗吸附效應及生物相容性之相關性探討 16
2.4材料水合作用之探討 21
2.4.1熱分析法(Thermal analysis) 21
2.4.2光譜分析 24
2.5 雙離子材料合成方法及聚合參數效應回顧 28
第三章 實驗材料與方法 34
3.1 實驗藥品與設備 34
3.1.1實驗藥品 34
3.1.2 實驗儀器設備 34
3.2實驗儀器原理 35
3.2.1 熱示差掃描卡量計(Differential scanning calorimetry, DSC) 35
3.2.2 核磁共振光譜儀 (Nuclear Magnetic Resonance spectroscopy, NMR) 36
3.2.3 傅立葉紅外線光譜儀 (Fourier Transform Infrared Spectrometer, FTIR) 36
3.2.4 膠體滲透層析儀 (Gel Permeation Chromatography, GPC) 37
3.3 實驗方法 37
3.3.1 合成 carboxybetaine methacrylamide (CBAA-1,3,5)單體 37
3.3.2 Poly CBAA聚合 43
3.3.3 GPC量測 45
3.3.4 熱示差掃描卡量計(DSC) 分析 46
第四章 結果與討論 47
4.1 CBAA聚合條件之探討 47
4.1.1 離子間距對於雙離子高分子聚合之效應 47
4.1.2 反應時間對高分子聚合之效應 48
4.1.3 起始劑濃度對高分子聚合之效應 51
4.1.4 絕對濃度對高分子聚合之效應 53
4.1.5 混合方式對高分子聚合之效應 54
4.1.6 起始劑與溶劑對高分子聚合之效應 55
4.2 雙離子型高分子水合性質探討 57
4.2.1 不同水合狀態之DSC吸熱峰特徵 58
4.2.2 陰離子基團之水合效應 71
4.2.3 陰陽離子基團間距對之水合效應之影響 74
第五章 結論與未來展望 78
第六章、參考文獻 80

 
圖目錄
圖2-1、雙離子型高分子電荷分佈示意圖[1] 4
圖2-2、雙離子官能基團[17] 5
圖2-3、2-methacryloyloxyethyl phosphorylcholine (MPC)單體合成示意圖[21] 5
圖2-4、SBMA與SBAA高分子結構式[17] 6
圖2-5、SBMA與CBMA結構比較圖[28] 7
圖2-6、Carboxybetaine acrylamide (CBAA) 單體結構與接枝表面示意圖[29] 7
圖2-7、PEG修飾基材與蛋白質作用示意圖[32] 9
圖2-8、(A)修飾材料分子被完全排除於蛋白質表面(local domain)示意圖;(B)材料表面抵抗蛋白質吸附之示意圖[30] 10
圖2-9、材料表面水合層之示意圖[1] 10
圖2-10、PEG鏈段於表面接枝型態圖[31] 11
圖2-11、Sulfobetaine (SB)雙離子表面結構及分子鏈間之作用示意圖[33] 12
圖2-12、Sulfobetaine (SB)雙離子高分子膜厚對表面親水性及膨潤度之影響[32] 12
圖2-13、不同緻密程度(10%, 50%, 100%)之sulfobetaine表面聚合時膜厚增長速率及膜厚對表面接觸角之影響[33] 13
圖2-14、poly(SBMA)修飾表面膜厚對蛋白質吸附量之影響[34] 13
圖2- 15、溶液中離子強度對sulfobetaine自組裝單層膜蛋白質吸附量之影響[23] 14
圖2-16、不同離子強度溶液(NaCl)對不同膜厚之poly(SBMA)抗蛋白質(fibrinogen) 吸附效果的影響 (b) 膜厚7nm 之 poly(SBMA) 表面在不同濃度、種類之鹽類溶液中纖維蛋白原 (fibrinogen) 吸附量比較[34] 15
圖2-17、Carboxybetaine(CB)類雙離子型高分子質子化示意圖[29] 15
圖2-18、不同離子間距(spacer length)之CBAA其表面蛋白質吸附量在不同溶液酸鹼度、不同離子強度下的表現[29] 16
圖2-19、不同官能基及EG鏈長之自組性單層膜在PBS緩衝溶液之AFM量測圖[36] 17
圖2-20、PMEA升溫過程之DSC掃描圖譜[37] 18
圖2-21、(a)(b)不同表面之free water及bound water含量與血小板貼附關係圖；(c)不同水合層與表面接觸角之關係圖；(d)不同表面之接觸角與血小板貼附之關係圖[37] 19
圖2-22 、不同含水量之PMEA掃描圖譜積分後各水合層之分析數值[38] 20
圖2-23、不同共聚高分子之DSC掃描圖譜[39] 20
圖2-24、(a)poly(MPC) hydrogel之DSC圖；(b) poly(Me(EG)4MA) hydrogel之DSC圖；(c) poly(Me(EG)8MA) hydrogel之DSC圖；(d)不同含水量之hydrogel nonfreezing water含量[10] 21
圖2-25、水合狀態分類 23
圖2- 26、升溫過程中DSC與TGA測量圖譜[40] 23
圖2-27、穿透式(transmission IR) [43]與全反射式(ATR-IR) [44]密閉裝置圖 25
圖2-28、a. Poly(HEMA)表面吸收飽和水蒸氣及注水方式光譜比較，虛線為兩者相減後光譜圖; b. 不同表面及純水之吸收光譜圖。(a) PHEMA, (b) PMEA, (c) PMMA, (d) PVME, and (e) free water. [42] 26
圖2-29、PMEA表面注入水後吸收/脫附之變化[44] 27
圖2-30、CBAA2單體合成及聚合反應式 29
圖2-31、不同聚合條件下CBAA2的聚合情形 30
圖2-32、CBAA2聚合實驗轉化率及分子量關係圖。a) 70 °C, [CTA]/[I] = 2，b) 70 °C, [CTA]/[I] = 5，c) 70 °C, [CTA]/[I] = 8，d) 37 °C, [CTA]/[I] = 5 30
圖2-33、SBMA之聚合反應式 32
圖2-34、pSBMA之GPC圖譜(引發劑濃度0.08％（S1），0.13％（S2），0.26％（S3）和0.63％（S4）) 32
圖3-1、合成CBAA單體示意圖(n=1,3,5) 37
圖3-2、CBAA-1及其ester之氫譜NMR與FTIR光譜 39
圖3-3、CBAA-3及其ester之氫譜NMR與FTIR光譜 41
圖3-4、CBAA-5及其ester之氫譜NMR與FTIR光譜 42
圖3-5、pCBAA反應示意圖 43
圖3-6、pCBAA-1之氫譜NMR與FTIR光譜 44
圖3-7、pCBAA-3之氫譜NMR與FTIR光譜 44
圖3-8、pCBAA-5之氫譜NMR與FTIR光譜 45
圖4-1、探討正負離子間距之效應 48
圖4-2、反應時間對CBAA-1聚合之影響 50
圖4-3、CBAA-3和CBAA-5在[mono]/ [ini]=1733條件下，反應時間之效應探討 50
圖4-4、起始劑濃度對CBAA-1聚合之影響。*此筆數偏差較大，待重新商榷 52
圖4-5、探討固定[單體]/[起始劑]比值，改變[起始劑]及[單體]之絕對濃度之效應 53
圖4-6、混合方式對CBAA-1聚合之影響。T：單體及起始劑同時溶解；S：單體先溶解，再與起始劑混合；U：分別溶解單體和起始劑再混合 54
圖4-7、a. 起始劑與b. 溶劑對CBAA-3聚合之影響。[mono]/[ini]= 250。A：醋酸水溶液，B：酒精水溶液 56
圖4-8、pCBAA3樣品於升降溫過程中水分子吸/放熱圖, Rn=18.3 57
圖4-9、pSBAA-3在不同水量之DSC升溫掃描結果. (a) 升溫譜線疊圖; (b)各水合層出現之溫度趨勢圖 60
圖4-10、SBAA-3單體在不同水量之DSC升溫掃描結果. (a) 升溫譜線疊圖; (b)各水合層出現之溫度趨勢圖 61
圖4-11、pCBAA-1在不同水量之DSC升溫掃描結果. (a) 升溫譜線疊圖; (b)各水合層出現之溫度趨勢圖 63
圖4-12、CBAA-1單體在不同水量之DSC升溫掃描結果. (a) 升溫譜線疊圖; (b)各水合層出現之溫度趨勢圖 64
圖4-13、pCBAA-3在不同水量之DSC升溫掃描結果. (a) 升溫譜線疊圖; (b)各水合層出現之溫度趨勢圖 66
圖4-14、CBAA-3單體在不同水量之DSC升溫掃描結果. (a) 升溫譜線疊圖; (b)各水合層出現之溫度趨勢圖 67
圖4-15、pCBAA-5在不同水量之DSC升溫譜線疊圖 69
圖4-16、CBAA-5單體在不同水量之DSC升溫掃描結果. (a) 升溫譜線疊圖; (b)各水合層出現之溫度趨勢圖 70
圖4-17、pSBAA-3於不同含水量之各水合層熱焓量化趨勢圖 72
圖4-18、pCBAA-3於不同含水量之各水合層熱焓量化趨勢圖 73
圖4-19、SBAA-3單體於不同含水量之各水合層熱焓量化趨勢圖 73
圖4-20、CBAA-3單體於不同含水量之各水合層熱焓量化趨勢圖 74
圖4-21、pCBAA1於不同含水量之各水合層熱焓量化趨勢圖 75
圖4-22、pCBAA5於不同含水量之各水合層熱焓量化趨勢圖 75
圖4-23、CBAA1單體於不同含水量之各水合層熱焓量化趨勢圖 76
圖4-24、CBAA5單體於不同含水量之各水合層熱焓量化趨勢圖 76

[1] S. Chen, L. Li, C. Zhao, and J. Zheng, "Surface hydration: Principles and applications toward low-fouling/nonfouling biomaterials," Polymer, vol. 51, no. 23, pp. 5283-5293, 2010.
[2] Z. Zhang, T. Chao, S. Chen, and S. Jiang, "Superlow fouling sulfobetaine and carboxybetaine polymers on glass slides," Langmuir, vol. 22, no. 24, pp. 10072-10077, 2006.
[3] C.-G. Gölander, J. N. Herron, K. Lim, P. Claesson, P. Stenius, and J. Andrade, "Properties of immobilized PEG films and the interaction with proteins," in Poly (ethylene glycol) Chemistry: Springer, 1992, pp. 221-245.
[4] K. L. Prime and G. M. Whitesides, "Adsorption of proteins onto surfaces containing end-attached oligo (ethylene oxide): a model system using self-assembled monolayers," Journal of the American Chemical Society, vol. 115, no. 23, pp. 10714-10721, 1993.
[5] A. Halperin, "Polymer brushes that resist adsorption of model proteins: design parameters," Langmuir, vol. 15, no. 7, pp. 2525-2533, 1999.
[6] J.-F. Lutz, Ö. Akdemir, and A. Hoth, "Point by point comparison of two thermosensitive polymers exhibiting a similar LCST: is the age of poly (NIPAM) over?," Journal of the American Chemical Society, vol. 128, no. 40, pp. 13046-13047, 2006.
[7] R. G. Chapman, E. Ostuni, S. Takayama, R. E. Holmlin, L. Yan, and G. M. Whitesides, "Surveying for surfaces that resist the adsorption of proteins," Journal of the American Chemical Society, vol. 122, no. 34, pp. 8303-8304, 2000.
[8] E. Ostuni, R. G. Chapman, R. E. Holmlin, S. Takayama, and G. M. Whitesides, "A survey of structure− property relationships of surfaces that resist the adsorption of protein," Langmuir, vol. 17, no. 18, pp. 5605-5620, 2001.
[9] N. Efremova, S. Sheth, and D. Leckband, "Protein-induced changes in poly (ethylene glycol) brushes: molecular weight and temperature dependence," Langmuir, vol. 17, no. 24, pp. 7628-7636, 2001.
[10] T. Morisaku, J. Watanabe, T. Konno, M. Takai, and K. Ishihara, "Hydration of phosphorylcholine groups attached to highly swollen polymer hydrogels studied by thermal analysis," Polymer, vol. 49, no. 21, pp. 4652-4657, 2008.
[11] H. Kitano et al., "Structure of water incorporated in sulfobetaine polymer films as studied by ATR‐FTIR," Macromolecular bioscience, vol. 5, no. 4, pp. 314-321, 2005.
[12] S. Chen and S. Jiang, "An new avenue to nonfouling materials," Advanced Materials, vol. 20, no. 2, pp. 335-338, 2008.
[13] M. Rubinstein and A. V. Dobrynin, "Associations leading to formation of reversible networks and gels," Current opinion in colloid & interface science, vol. 4, no. 1, pp. 83-87, 1999.
[14] J. Zheng, Y. He, S. Chen, L. Li, M. T. Bernards, and S. Jiang, "Molecular simulation studies of the structure of phosphorylcholine self-assembled monolayers," The Journal of chemical physics, vol. 125, no. 17, p. 174714, 2006.
[15] Y. He, Y. Chang, J. C. Hower, J. Zheng, S. Chen, and S. Jiang, "Origin of repulsive force and structure/dynamics of interfacial water in OEG–protein interactions: a molecular simulation study," Physical Chemistry Chemical Physics, vol. 10, no. 36, pp. 5539-5544, 2008.
[16] S. Chen, J. Zheng, L. Li, and S. Jiang, "Strong resistance of phosphorylcholine self-assembled monolayers to protein adsorption: insights into nonfouling properties of zwitterionic materials," Journal of the American Chemical Society, vol. 127, no. 41, pp. 14473-14478, 2005.
[17] J. B. Schlenoff, "Zwitteration: coating surfaces with zwitterionic functionality to reduce nonspecific adsorption," Langmuir, vol. 30, no. 32, pp. 9625-9636, 2014.
[18] D. S. Johnston, S. Sanghera, M. Pons, and D. Chapman, "Phospholipid polymers—synthesis and spectral characteristics," Biochimica et Biophysica Acta (BBA)-Biomembranes, vol. 602, no. 1, pp. 57-69, 1980.
[19] J. A. Hayward and D. Chapman, "Biomembrane surfaces as models for polymer design: the potential for haemocompatibility," Biomaterials, vol. 5, no. 3, pp. 135-142, 1984.
[20] Y. Kadoma, "Synthesis and hemolysis test of the polymer containing phosphorylcholine groups," Koubunshi Ronbunshu, vol. 35, pp. 423-427, 1978.
[21] K. Ishihara, "Successful Development of Biocompatible Polymers Designed by Natures Original Inspiration," Procedia Chemistry, vol. 4, pp. 34-38, 2012.
[22] Y. Iwasaki and K. Ishihara, "Cell membrane-inspired phospholipid polymers for developing medical devices with excellent biointerfaces," Science and technology of advanced materials, vol. 13, no. 6, p. 064101, 2012.
[23] R. E. Holmlin, X. Chen, R. G. Chapman, S. Takayama, and G. M. Whitesides, "Zwitterionic SAMs that resist nonspecific adsorption of protein from aqueous buffer," Langmuir, vol. 17, no. 9, pp. 2841-2850, 2001.
[24] Y. Chang, S. Chen, Z. Zhang, and S. Jiang, "Highly protein-resistant coatings from well-defined diblock copolymers containing sulfobetaines," Langmuir, vol. 22, no. 5, pp. 2222-2226, 2006.
[25] Z. Zhang, S. Chen, Y. Chang, and S. Jiang, "Surface grafted sulfobetaine polymers via atom transfer radical polymerization as superlow fouling coatings," The Journal of Physical Chemistry B, vol. 110, no. 22, pp. 10799-10804, 2006.
[26] J. Ladd, Z. Zhang, S. Chen, J. C. Hower, and S. Jiang, "Zwitterionic polymers exhibiting high resistance to nonspecific protein adsorption from human serum and plasma," Biomacromolecules, vol. 9, no. 5, pp. 1357-1361, 2008.
[27] Q. Shao, Y. He, A. D. White, and S. Jiang, "Difference in hydration between carboxybetaine and sulfobetaine," The Journal of Physical Chemistry B, vol. 114, no. 49, pp. 16625-16631, 2010.
[28] H. Chen, L. Yuan, W. Song, Z. Wu, and D. Li, "Biocompatible polymer materials: role of protein–surface interactions," progress in polymer science, vol. 33, no. 11, pp. 1059-1087, 2008.
[29] Z. Zhang, H. Vaisocherová, G. Cheng, W. Yang, H. Xue, and S. Jiang, "Nonfouling behavior of polycarboxybetaine-grafted surfaces: structural and environmental effects," Biomacromolecules, vol. 9, no. 10, pp. 2686-2692, 2008.
[30] R. S. Kane, P. Deschatelets, and G. M. Whitesides, "Kosmotropes form the basis of protein-resistant surfaces," Langmuir, vol. 19, no. 6, pp. 2388-2391, 2003.
[31] W. Norde and D. Gage, "Interaction of bovine serum albumin and human blood plasma with PEO-tethered surfaces: influence of PEO chain length, grafting density, and temperature," Langmuir, vol. 20, no. 10, pp. 4162-4167, 2004.
[32] O. Azzaroni, A. A. Brown, and W. T. Huck, "UCST wetting transitions of polyzwitterionic brushes driven by self‐association," Angewandte Chemie International Edition, vol. 45, no. 11, pp. 1770-1774, 2006.
[33] N. Cheng, A. A. Brown, O. Azzaroni, and W. T. Huck, "Thickness-dependent properties of polyzwitterionic brushes," Macromolecules, vol. 41, no. 17, pp. 6317-6321, 2008.
[34] W. Yang et al., "Film thickness dependence of protein adsorption from blood serum and plasma onto poly (sulfobetaine)-grafted surfaces," Langmuir, vol. 24, no. 17, pp. 9211-9214, 2008.
[35] Y. Chang, S.-C. Liao, A. Higuchi, R.-C. Ruaan, C.-W. Chu, and W.-Y. Chen, "A highly stable nonbiofouling surface with well-packed grafted zwitterionic polysulfobetaine for plasma protein repulsion," Langmuir, vol. 24, no. 10, pp. 5453-5458, 2008.
[36] T. Hayashi, Y. Tanaka, Y. Koide, M. Tanaka, and M. Hara, "Mechanism underlying bioinertness of self-assembled monolayers of oligo (ethyleneglycol)-terminated alkanethiols on gold: protein adsorption, platelet adhesion, and surface forces," Physical Chemistry Chemical Physics, vol. 14, no. 29, pp. 10196-10206, 2012.
[37] M. Tanaka and A. Mochizuki, "Clarification of the blood compatibility mechanism by controlling the water structure at the blood–poly (meth) acrylate interface," Journal of Biomaterials Science, Polymer Edition, vol. 21, no. 14, pp. 1849-1863, 2010.
[38] M. Tanaka et al., "Cold crystallization of water in hydrated poly (2‐methoxyethyl acrylate)(PMEA)," Polymer international, vol. 49, no. 12, pp. 1709-1713, 2000.
[39] K. Ishihara, H. Nomura, T. Mihara, K. Kurita, Y. Iwasaki, and N. Nakabayashi, "Why do phospholipid polymers reduce protein adsorption?," Journal of Biomedical Materials Research: An Official Journal of The Society for Biomaterials, The Japanese Society for Biomaterials, and the Australian Society for Biomaterials, vol. 39, no. 2, pp. 323-330, 1998.
[40] H. Hatakeyama and T. Hatakeyama, "Interaction between water and hydrophilic polymers," Thermochimica acta, vol. 308, no. 1-2, pp. 3-22, 1998.
[41] M. Tanaka, T. Hayashi, and S. Morita, "The roles of water molecules at the biointerface of medical polymers," Polymer Journal, vol. 45, no. 7, p. 701, 2013.
[42] H. Kitano, K. Ichikawa, M. Fukuda, A. Mochizuki, and M. Tanaka, "The Structure of Water Sorbed to Polymethoxyethylacrylate Film as Examined by FT–IR Spectroscopy," Journal of colloid and interface science, vol. 242, no. 1, pp. 133-140, 2001.
[43] T. Tajiri, S. Morita, and Y. Ozaki, "Time-resolved conformational analysis of poly (ethylene oxide) during the hydrogelling process," Polymer, vol. 52, no. 24, pp. 5560-5566, 2011.
[44] S. Morita, M. Tanaka, and Y. Ozaki, "Time-resolved in situ ATR-IR observations of the process of sorption of water into a poly (2-methoxyethyl acrylate) film," Langmuir, vol. 23, no. 7, pp. 3750-3761, 2007.
[45] H. Kitano, M. Imai, K. Sudo, and M. Ide, "Hydrogen-bonded network structure of water in aqueous solution of sulfobetaine polymers," The Journal of Physical Chemistry B, vol. 106, no. 43, pp. 11391-11396, 2002.
[46] H. Kitano et al., "Correlation between the structure of water in the vicinity of carboxybetaine polymers and their blood-compatibility," Langmuir, vol. 21, no. 25, pp. 11932-11940, 2005.
[47] Z. Zhang, G. Cheng, L. R. Carr, H. Vaisocherová, S. Chen, and S. Jiang, "The hydrolysis of cationic polycarboxybetaine esters to zwitterionic polycarboxybetaines with controlled properties," Biomaterials, vol. 29, no. 36, pp. 4719-4725, 2008.
[48] C. Rodriguez‐Emmenegger et al., "Low temperature aqueous living/controlled (RAFT) polymerization of carboxybetaine methacrylamide up to high molecular weights," Macromolecular rapid communications, vol. 32, no. 13, pp. 958-965, 2011.
[49] R. Zhou, P.-F. Ren, H.-C. Yang, and Z.-K. Xu, "Fabrication of antifouling membrane surface by poly (sulfobetaine methacrylate)/polydopamine co-deposition," Journal of membrane science, vol. 466, pp. 18-25, 2014.
[50] R. Lalani and L. Liu, "Synthesis, characterization, and electrospinning of zwitterionic poly (sulfobetaine methacrylate)," Polymer, vol. 52, no. 23, pp. 5344-5354, 2011.