聚砜类超滤膜表面两性离子化及其性能的研究

发布时间：2018-05-31 08:16

  本文选题：聚砜类超滤膜 + 两性离子　； 参考：《浙江大学》2015年博士论文

【摘要】：芳香族聚砜有着优异的化学稳定性、热稳定性、机械强度以及良好的可加工性,是超／微滤膜的主流材质之一。事实上,聚砜类超滤膜已被广泛应用于水处理、食品饮料纯化、蛋白质分离、血液透析、生物医药分离等领域。然而,在液体过滤中,聚砜膜自身较强的疏水性,容易引发天然有机物、蛋白质、胶体等污染质在膜表面和膜孔内吸附和积聚,造成膜污染,劣化膜性能,缩短膜的使用寿命。在生物医用领域,疏水性聚砜膜会激发蛋白质吸附和血小板粘附,可能引发凝血／血栓、免疫排斥等严重问题。因此,聚砜膜在使用之前常常需要进行改性,以满足膜材料的多方面性能需求。为克服已有改性方法的不足,本论文从分子结构设计出发,合成出一系列适宜用于聚砜类超滤膜改性的反应性两亲共聚物,综合采用溶液共混和膜表面反应的方法,将具有极强水合能力的两性离子聚合物链引入膜表面,以改善聚砜类超滤膜的亲水性／透水性、抗污染能力和血液相容性。首先通过缩聚反应合成羟基封端的聚砜遥爪聚合物,通过端羟基的反应特性,采用原子转移自由基聚合和可逆加成-断裂链转移自由基聚合,分别合成两亲性嵌段共聚物PSF-b-PDMAEMA和PES-b-PDMAEMA。通过非溶剂诱导相转化法(NIPS)制备聚砜类共混膜PSF/PSF-b-PDMAEMA和PES/PES-b-PDMAEMA,两亲性共聚物自发向膜表面迁移／富集,共混膜的亲水性和渗透性能都得到提高,并表现出一定的刺激响应性。同时,表面富集的PDMAEMA为膜表面改性提供了二次修饰的平台,分别采用3-溴丙酸、1,3-丙磺酸内酯和溴癸烷与PDMAEMA进行季铵化反应,得到聚羧酸型两性离子、聚磺酸型两性离子和聚阳离子修饰的聚砜类膜。研究结果表明,两性离子化的聚砜类超滤膜表现出优良的抗污染性和血液相容性,阳离子化膜表现出优异的抗菌性。以末端带羟基的PES遥爪聚合物为前体,通过RAFT反应成功合成两亲嵌段共聚物PES-b-PHEMA,通过调节聚合时间可有效调节嵌段聚合物的分子量。与PES共混得到PES/PES-b-PHEMA共混膜,PES-b-PHEMA在成膜过程中向表面富集,利用表面富集的PHEMA将含溴基团的引发剂固定在膜表面,而后将聚磺酸基甜菜碱(PSBMA)通过ATRP反应接枝到PES共混膜表面。该接枝反应具有活性可控的特征,接枝量与反应时间呈现线性增长关系。表面接枝PSBMA后,PES膜表面化学组成和形貌发生较大改变,亲水性有明显提高。改性膜对蛋白质和油的分离能力明显提高,并可有效减弱蛋白质或油污因吸附造成的不可逆污染,显著提高了PES膜的抗污染性能。改性膜具有明显的电解质响应性,随着溶液中电解质浓度提高,通量逐渐减小,同时该响应性是可逆的。此夕,PSBMA接枝层能够抑制血小板在膜表面的粘附与变性,延长血浆复钙化时间,改善了PES膜的血液相容性。合成含双键官能团的聚醚砜共聚物PES-b-PHEDMA,通过NIPS法制备PES/PES-b-PHEDMA共混膜。在相转化过程中,两亲性共聚物向表面富集,共混膜表面含有活性双键官能团。再以PEGDA为交联剂,通过膜表面双键和两性离子单体SBMA的自由基交联反应,在PES膜表面生成两性离子凝胶层。膜表面的孔径及孔隙率略有下降,对BSA的截留率明显提高,有效提高了PES膜对BSA的分离效率。由于两性离子凝胶层较强的水合能力,表面固定凝胶层之后PES膜的亲水性和保水性都得到显著提高,同时表现出优异的抗污染性和血液相容性。由于共混的两亲性共聚物与膜本体材料相互缠结,后续交联反应引入的凝胶层也通过共价键连接,凝胶层在PES膜表面保持持久稳定的改性效果。为了进一步提高两亲性共聚物的改性效率,提高聚砜膜的蛋白质分离性能,首先合成聚醚砜两性离子共聚物PES-b-PSBMA,其在水溶液中发生自组装形成具有核壳结构的球形胶束。将PES-b-PSBMA胶束通过过滤沉积的方法均匀地沉积在聚砜膜表面,制备PSF/PES-b-PSBMA复合膜。通过ATR-FTIR、XPS和SEM分析复合膜的表面化学组成和形貌,并证明该胶柬成功沉积在膜表面。PSF/PES-b-PSBMA复合膜的亲水性比PSF基膜有所提高,水通量略有降低。蛋白质分离性能得到大幅度提升,对BSA的截留率从42%提高到96%以上,对LYZ和BSA的分离因子从1.8提高到29。该方法制备的膜在蛋白质分离提纯领域有着广阔的应用前景,并为聚合物分离膜的功能化改性开辟了新的思路。综上所述,通过聚砜基两亲性共聚物的分子设计,结合共混改性和后续表面反应,可实现聚砜类超滤膜的表面两性离子化,显著提高聚砜膜的抗生物污染性、血液相容性和分离性能,为实现聚砜类超滤膜的高性能化提供了理论和技术支撑。
[Abstract]:Aromatic polysulfone has excellent chemical stability, thermal stability, mechanical strength and good machinability. It is one of the main materials of ultrafiltration membrane. In fact, polysulfone ultrafiltration membrane has been widely used in the fields of water treatment, food and beverage purification, protein separation, hemodialysis, biological medicine separation and so on. However, in liquid filtration, the membrane is used in liquid filtration. The polysulfone membrane has strong hydrophobicity, which can easily lead to the adsorption and accumulation of natural organic, protein, colloid and other contaminants in the surface and pore of the membrane, causing membrane fouling, deterioration membrane performance and shortening the service life of the membrane. In the biomedical field, the hydrophobic polysulfone membrane will stimulate protein adsorption and platelet adhesion, and may lead to coagulation / thrombus. Therefore, the polysulfone membrane often needs to be modified before it is used to meet the multifaceted performance requirements of the membrane material. In order to overcome the shortcomings of the existing modified methods, a series of reactive two Pro copolymer suitable for polysulfone ultrafiltration membrane modification has been synthesized in order to overcome the shortcomings of the existing modified methods. In order to improve the hydrophilic / permeable property, pollution resistance and blood compatibility of polysulfone ultrafiltration membrane, the hydrophilic / permeable property, pollution resistance and blood compatibility of polysulfone ultrafiltration membrane have been introduced into the membrane surface by the method of liquid mixing and membrane surface reaction. First, polysulfone teleclaws polymer with hydroxyl terminated terminated by polycondensation is synthesized by condensation reaction. Two amphiphilic block copolymers, PSF-b-PDMAEMA and PES-b-PDMAEMA., were synthesized by atom transfer radical polymerization and reversible addition - fracture chain transfer free radical polymerization, respectively, to prepare polysulfone blend membranes PSF/PSF-b-PDMAEMA and PES/PES-b-PDMAEMA by non solvent induced phase transformation (NIPS). The two amphiphilic copolymers migrate to the surface of the membrane spontaneously and blend. The hydrophilic and permeable properties of the membrane were improved and showed a certain stimulus responsiveness. At the same time, the surface enriched PDMAEMA provided two modified platforms for the surface modification of the membrane. 3- bromopropionic acid, 1,3- propionic acid lactone and bromo decane were used for quaternylation, and polycarboxylic amphoteric ions, polysulfonic amphoteric sexes were obtained. The polysulfone membrane modified by ions and polycation shows that the amphoteric polysulfone ultrafiltration membrane has excellent antifouling and blood compatibility, and the cationic membrane exhibits excellent antibacterial properties. The PES tele polymer with the hydroxyl group at the end is used as the precursor, and the two parent block copolymer PES-b-PHEMA is successfully synthesized through the RAFT reaction. The molecular weight of the block polymer can be adjusted effectively by adjusting the polymerization time. PES/PES-b-PHEMA blend membrane is blended with PES. PES-b-PHEMA is enriched in the film forming process. The brominated group initiator is immobilized on the membrane surface by the surface enriched PHEMA, and then the polysulfonyl betaine (PSBMA) is grafted to PES by ATRP reaction. On the surface of the membrane, the graft reaction has the characteristics of active and controllable activity, the grafting amount and the reaction time show a linear growth relationship. After the surface grafting of PSBMA, the surface chemical composition and morphology of the PES film are greatly changed, the hydrophilic property is obviously improved. The separation ability of the modified membrane to protein and oil is obviously improved, and the protein or oil pollution can be effectively weakened. The irreversible pollution caused by the attached membrane significantly improves the anti pollution performance of the PES membrane. The modified membrane has an obvious electrolyte response. With the increase of the electrolyte concentration, the flux gradually decreases and the response is reversible. On this night, the PSBMA graft layer can inhibit the adhesion and denaturation of the platelets on the membrane surface and prolong the time of the plasma calcification. The blood compatibility of the PES membrane was improved. The Polyethersulfone copolymer PES-b-PHEDMA containing the double bond functional group was synthesized and the PES/PES-b-PHEDMA blend membrane was prepared by the NIPS method. In the phase transformation, the two amphiphilic copolymers were enriched to the surface, and the surface of the blend membrane contained active double bond functional groups. And then PEGDA was used as the crosslinker, through the double bond surface and the amphoteric ion single. The free radical crosslinking reaction of the body SBMA produces an amphoteric ion gel layer on the surface of the PES membrane. The pore size and porosity of the membrane surface decreases slightly, the interception rate of the BSA is obviously improved, and the separation efficiency of the PES film to BSA is effectively improved. The hydrophilic property and water retention of the PES film after the gel layer is fixed on the surface of the gels with the strong hydration ability of the gels. Both of the two amphiphilic copolymers were entangled with the bulk of the membrane, the gel layer introduced by the subsequent crosslinking reaction was also linked through the covalent bond, and the gel layer maintained a lasting and stable modification effect on the surface of the PES membrane. In order to further improve the two amphiphilic copolymers. In order to improve the protein separation performance of polysulfone membrane, the Polyethersulfone amphoteric ion copolymer PES-b-PSBMA was first synthesized, and a spherical micelle with nuclear shell structure was formed by self assembly in aqueous solution. The PES-b-PSBMA micelle was deposited evenly on the surface of polysulfone membrane by filtering and deposition, and the PSF/PES-b-PSBMA composite membrane was prepared. ATR-FTIR, XPS and SEM were used to analyze the surface chemical composition and morphology of the composite membrane. It was proved that the hydrophilic property of the.PSF/PES-b-PSBMA composite film deposited on the membrane surface was higher than that of the PSF film, and the water flux decreased slightly. The separation performance of the protein was greatly improved, the interception rate of BSA was increased from 42% to over 96%, and the separation of LYZ and BSA was found. The separation factor from 1.8 to 29. has a wide application prospect in the field of protein separation and purification, and opens a new idea for the functional modification of the polymer separation membrane. In summary, the polysulfone ultrafiltration membrane can be realized by the molecular design of the polysulfone based two parent copolymer, the blending modification and the subsequent surface reaction. The surface amphoteric ionization significantly improves the biopollution resistance, blood compatibility and separation performance of polysulfone membrane, which provides theoretical and technical support for the high performance of polysulfone ultrafiltration membrane.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ051.893
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本文编号：1958935