新型聚合物分离材料的制备与应用研究

发布时间：2018-01-25 22:40

本文关键词： 气体分离聚酰亚胺抗溶胀自具微孔高分子超疏水-超亲油油水分离选择性吸附　出处：《北京化工大学》2017年博士论文　论文类型：学位论文

【摘要】：随着社会的快速发展,环境问题也变得越来越严重,甚至威胁到人类正常的生活。来自工业污水和烟道气体的排放对人类及整个生态环境的破坏已经受到了越来越多人的关注。因此用于气体分离、污水处理的新型环境修复材料的研发显得尤为重要。材料自身孔结构的大小及分布是评价分离材料分离性能的一个最主要标志。自具微孔高分子材料(Polymers of Intrinsic Microporosity,PIMs)是由含螺旋结构(Spiro-center)的芳香族单体之间通过缩聚反应得到,由于刚性分子链的高度扭曲结构使聚合物自身带来了高比表面积,同时由稠环结构形成的分子链使得聚合物具有非常好的热稳定性。PIMs主要被用于气体分离,吸附和储氢等几方面。聚酰亚胺材料由于具有良好的机械性能、热稳定性、化学稳定性并在气体分离方面表现出良好的选择性,因此被广泛的应用到气体分离膜的制备中。但是,目前聚酰亚胺气体分离膜材料主要存在气体渗透性较低,天然气提纯中易被酸性气体(CO2和H2S等)塑化等问题。为了提高聚酰亚胺材料的气体渗透性,受PIMs材料的启发,在聚酰亚胺主链中引入螺旋结构可以有效的降低材料的堆积密度,从而提高其气体渗透性能;为了消除材料的塑化现象,通过在聚酰亚胺的侧基引入可交联的基团,采用交联法来提高材料的抗溶胀性能。本论文主要研究了新型分离材料PIM-1和主链含螺旋、Cardo结构的聚酰亚胺及含羧基的可进行交联反应的聚酰亚胺膜材料的制备以及这些材料分别在在油水分离、吸附及气体分离等几方面的应用。1.首先合成三种含不同取代基(-CF3,-CH3,-H)的基于Spirobichroman 结构的二胺单体(FSBC,MSBC,SBC)。然后三种二胺分别与4,4'-(六氟异丙基)-苯二酸酐(6FDA)发生反应生成三种主链含螺旋结构的聚酰亚胺(6FDA-FSBC,6FDA-MSBC,6FDA-SBC)。系统的研究了三种聚酰亚胺的溶解性,分子量(Mn),密度,玻璃化转变温度(Tg),热稳定性,自由体积分数(FFV),分子链间距(d-spacing)及这些因素对聚酰亚胺膜气体分离性能的影响。三种聚酰亚胺都能很好的溶于常见的各种有机溶剂中,并且具有较高的分子量,因此用溶剂挥发法能得到机械性能良好的聚合物致密膜。三种不同取代基的聚酰亚胺中,6FDA-FSBC的气体分离性能最接近Robeson上限。这主要归因于两个因素,一方面,侧基-CF3为体积较大的取代基,-CF3的引入有效的阻止了分子链的紧密堆积,另一方面,主链所含的螺旋结构使相邻的六元环之间具有非共面特性,这两方面的原因使6FDA-FSBC具有较高的自由体积分数,并具有尺寸分布均一的孔结构,最终才使聚合物既有高的气体渗透性又有高的气体选择性。6FDA-MSBC在H2/CH4气体对的分离中表现出很好的选择性,这主要是由于-CH3取代基类似于“旋转门”的不停热运动有效阻止了大体积甲烷分子的扩散运动,而对小分子氢气的扩散运动几乎不产生影响,因此对H2/CH4气体对表现出很好的分离性能。2.双酚芴分别与不同取代基(-CF3, -CH3, -H)的单体反应经过硝化和还原两步合成三种不同取代基的含Cardo结构的二胺单体(FBPF,MBPF,BPF)。三种二胺分别与6FDA反应生成三种主链含 Cardo 结构的聚酰亚胺(6FDA-FBPF,6FDA-MBPF,6FDA-BPF)。三种聚酰亚胺都能很好的溶于常见的各种有机溶剂中,并且有较高的分子量,聚合物的玻璃化转变温度在260-270 ℃之间。三种不同取代基的聚酰亚胺中,6FDA-FBPF表现出较优异的分离性能。总的来说,含Cardo结构的聚酰亚胺气体分离性能与含Spirobichroman结构的聚酰亚胺进行对比,当取代基都为-CF3时,6FDA-FBPF对H2, N2,O2的气体渗透速率是略高于6FDA-FSBC的,而CH4和CO2的气体渗透速率要比6FDA-FSBC的低;而当取代基为-CH3和-H时,则6FDA-MSBC和6FDA-SBC的气体渗透速率高于与之对应的6FDA-MBPF和6FDA-BPF。但气体对的选择性,尤其是H2/CH4和H2/N2气体对的选择性,含Cardo结构的聚酰亚胺要高出含Spirobichroman结构的聚酰亚胺很多,表明Cardo结构的引入不利于大体积的气体分子扩散。3.通过硝化和还原两步法制备了侧基带羧基的两种不同取代基(-CF3,-H)的二胺单体(CADA1,CADA2)。CADA1 和 CADA2与6FDA,BTDA及DSDA三种二酐反应,生成四种侧基带羧基的聚酰亚胺(6FDA-CADA1,6FDA-CADA2 , BTDA-CADA1 和DSDA-CADA1)。系统的研究了不同结构的二胺、二酐及交联温度对得到的聚酰亚胺膜气体分离性能的影响。由于羧基的存在,使得聚合物中存在很强的氢键,导致交联之前膜气体渗透性能较低,其中6FDA-CADA1-200 的 CO2 渗透系数为 18.16 Barrer,CO2/CH4 的理想选择性为31.31。为了提高膜的气体渗透性及抗溶胀性,对含羧基的四种聚酰亚胺进行了热交联处理。与未经过热交联处理的膜相比,交联后的聚酰亚胺膜对CO2的渗透系数提高了 100倍左右,并且CO2/CH4气体对的选择性几乎不发生变化,同时还表现出良好的抗溶胀性能,交联后的聚合物膜在CO2压强为30 atm时仍然不发生塑化。随着热处理温度的增加,聚合物链间距也逐渐增加,其中6FDA-CADA1-450 和 DSDA-CADA1-450 的 d-spacing 分别为 5.81A和5.51A。交联后的分子链间距值与通过模拟软件计算的理论值接近(5.57A)。在 CO2/CH4 气体对的分离中,6FDA-CADA1-425,BTDA-CADA1-450 超过了 Robeson 2008 上限,其它在 400 和 425℃下热处理过的膜对CO2/CH4气体对的分离也都在Robeson 1991上限附近。4.通过缩聚反应成功制备了线性自具微孔高分子PIM-1,并通过FTIR,1H-NMR,TGA,BET和水接触角等一系列表征测试证明了聚合物的成功制备及聚合物自身具备的高比表面积及疏水性能。调节聚合物溶液的浓度及纺丝参数,通过静电纺丝法制备出了纤维直径为1.7μm、光滑、均一的PIM-1纤维膜,主要用于油水分离及吸附的应用。5.为了得到超疏水-超亲油的纤维膜,通过掺杂疏水性纳米粒子POSS来进行纤维表面修饰,最终当POSS含量达到40wt%时,制备出了水接触角为155°、油接触角为0°的超疏水-超亲油的纤维膜。40wt%PIM-1/POSS纤维膜既可以分离一系列不互溶的油水混合物,分离效率高达99.95%,也可以分离含表面活性剂和不含表面活性剂稳定的乳液状油水混合物,分离效率高达99.97%。经过多次循环使用之后,纤维膜的水接触角和通量变化不大。在苛刻的溶胀和超声环境下,POSS团聚颗粒仍保留在纤维表面,纤维膜仍表现出良好的超疏水性能。6.通过吸附法去除有机溶剂中的油溶性染料实现有机溶剂回收的目的。对比PIM-1致密膜和纤维的BET测试数据发现,纺丝纤维的比表面积,平均孔径,及介孔的孔体积都要高于致密膜,使得在吸附过程中,纤维的吸附速率要高出致密膜很多倍。用伪一级和伪二级吸附动力学拟合吸附过程,发现致密膜和纤维的吸附动力学都符合伪二级动力学,吸附过程中粒内扩散是速率控制步骤。PIM-1吸附油溶性染料的机理为π-π电子对之间的相互吸引作用。其中被吸附的染料分子中给电子的π电子云密度越强,则吸附量越高。7.通过对PIM-1纤维用不同浓度的氢氧化钠进行水解,制备了表面含羧基的水解纤维。由于水解后的PIM-1表面含有羧酸基团,一方面使得材料的亲水性大大增加,另一方面,由于羧基电离之后呈负电性,促使其能吸附水溶液中带正电的阳离子染料。其中对亚甲基蓝,番红O和甲基紫的饱和吸附量分别为424.80,364.29,和317.26 mg.g-1,然而,对甲基橙的饱和吸附量为42.38mg.g-1,与前三种阳离子染料的饱和吸附量相比,对阴离子染料甲基橙的吸附量非常低,所以,水解后的PIM-1具有选择性吸附溶液中阴阳离子混合染料的能力。分别用不同pH值的染料溶液和固体紫外进行分析得到,水解后的PIM-1吸附染料的机理为主客体之间电子对的相互作用,吸附过程使得两者的电子密度发生了变化。由于水解后PIM-1表面带负电的原因,促使其也可以吸附水溶液中的重金属离子,其中对Pb2+和Cu2+的吸附量分别为41.2和16.9 mg.g-1。
[Abstract]:With the rapid development of society, environmental problems are becoming more and more serious, and even a threat to people's normal life. Industrial wastewater and flue gas emissions from damage to human beings and the ecological environment has attracted more and more attention. Therefore for gas separation, sewage treatment research new environmental restoration materials is particularly important the size and distribution of materials. Its pore structure is the separation of performance evaluation of separation material, one of the major symbols. From a microporous polymer material (Polymers of Intrinsic Microporosity, PIMs) consists of helical structure (Spiro-center) between the aromatic monomer obtained by polycondensation reaction, due to the highly distorted structure of rigid chain polymer bring their own high specific surface area, and the molecular chain formed by the fused ring structure makes.PIMs polymer has very good thermal stability to be For gas separation, several aspects of the adsorption and hydrogen storage. The polyimide material because of its mechanical properties, good thermal stability, chemical stability and separation showed good selectivity in gas, so it is widely applied to gas separation membrane preparation. However, the polyimide gas separation membrane materials are mainly gas permeability low, natural gas is easy to acid gas purification (CO2 and H2S) and other issues. In order to improve the plasticizing gas permeability of polyimide materials, inspired by PIMs material, introducing the helical structure of the polyimide backbone can effectively reduce the bulk density of materials, so as to improve the gas permeability in order to eliminate the phenomenon of plastic; the material, by the introduction of the side group of polyimide crosslinkable groups, to improve the anti swelling properties of materials by crosslinking method. This paper mainly studies the new separation material Material PIM-1 and polymers containing spiral, polyimide Cardo structure and can be cross-linked polyimide film material containing carboxyl groups were prepared and these materials were separated in water, several aspects of application of.1. adsorption and gas separation of the first synthesis of three containing different substituents (-CF3, -CH3, -H) based on Spirobichroman structure the two amine monomer (FSBC, MSBC, SBC). Then three kinds of two amines respectively with 4,4'- (six heptafluoroisopropyl) - two benzene anhydride (6FDA) reacts with three kinds of helical structure of the main chain polyimide (6FDA-FSBC, 6FDA-MSBC, 6FDA-SBC). Systematic research on the solubility of three kinds of polyimide. The molecular weight (Mn), density, glass transition temperature (Tg), thermal stability, free volume fraction (FFV), molecular chain distance (d-spacing) and the influence of these factors on the separation performance of polyimide film gas. Three kinds of polyimide is well soluble in common A variety of organic solvents, molecular weight and high, so can polymer dense membrane with good mechanical properties obtained by solvent evaporation method. Three different substituents in polyimide, gas separation performance of 6FDA-FSBC is most close to the Robeson limit. This is mainly attributed to two factors, on the one hand, -CF3 is a substituent large side groups the volume of the introduction of -CF3 to effectively prevent the close packing of molecular chain, on the other hand, with non coplanar characteristics between the six membered ring containing the helix backbone adjacent to the free volume fraction of these two reasons that has higher 6FDA-FSBC, pore structure and has uniform size distribution, and finally make polymer not only has high gas permeability and high gas selectivity.6FDA-MSBC exhibited good selectivity in the separation of the H2/CH4 gas, which is mainly due to the -CH3 substituent is similar to the "revolving door" Don't stop the thermal motion effectively prevents the diffusion of large volume of methane, and the diffusion of small molecules of hydrogen has little effect, so the H2/CH4 gas is very good to show the separation performance of.2. with different substituents of bisphenol fluorene (-CF3, -CH3, -H) monomer reaction through nitration and reduction two step synthesis of three different substituents Cardo structure containing two amine monomer (FBPF, MBPF, BPF) three. Two respectively and 6FDA reaction of amine containing three kinds of Cardo structure of the main chain polyimide (6FDA-FBPF, 6FDA-MBPF, 6FDA-BPF). Three kinds of polyimide is well soluble in common organic solvents in, and has high molecular weight, glass transition temperature of the polymer in 260-270 DEG. Three different substituents in polyimide, 6FDA-FBPF exhibits excellent separation performance. In general, Cardo structure containing polyimide gas From the performance and structure of polyimide containing Spirobichroman were compared, when substituted for -CF3, 6FDA-FBPF H2, N2 O2, the gas permeation rate is slightly higher than that of 6FDA-FSBC, CH4 and CO2 and the gas permeation rate should be lower than 6FDA-FSBC; and when the substituent is -CH3 and -H, and the gas is 6FDA-MSBC 6FDA-SBC penetration rate is higher than the corresponding 6FDA-MBPF and 6FDA-BPF. but on gas selectivity, especially selective H2/CH4 and H2/N2 gas on the polyimide Cardo structure containing higher polyimide containing Spirobichroman structure, shows that the introduction of Cardo structure is not conducive to the diffusion of.3. gas molecular mass preparation of carboxyl side band two different substituents through nitration and reduction of two step method (-CF3, -H) two amine monomer (CADA1, CADA2).CADA1 and CADA2 and 6FDA, BTDA and DSDA three two anhydride, generating four carboxyl side band Polyimide (6FDA-CADA1,6FDA-CADA2, BTDA-CADA1 and DSDA-CADA1). Systematic study on the different structure of the two amines, two anhydride and crosslinking temperature on the separation performance of polyimide film gas are obtained. Due to the presence of carboxyl groups, which have very strong hydrogen bonds in the polymer induced membrane before cross-linking gas permeability is low, the 6FDA-CADA1-200 CO2 the permeability coefficient is 18.16 Barrer, the ideal CO2/CH4 selectivity of 31.31. in order to improve the membrane gas permeability and anti swelling, four kinds of polyimide containing carboxyl groups of thermal crosslinking. And without overheating cross-linked membranes compared to the permeability coefficient of polyimide film after crosslinking of CO2 is improved by about 100 times, and the selectivity of CO2/CH4 gas on the almost does not change, but also showed good anti swelling properties, polymer film after crosslinking at CO2 pressure of 30 ATM is still However, no plastic. With the increase of annealing temperature, the polymer chain spacing gradually increased, 6FDA-CADA1-450 and DSDA-CADA1-450 respectively. The d-spacing molecular chain spacing 5.81A and cross-linked 5.51A. values close to the theoretical values calculated by simulation software (5.57A). 6FDA-CADA1-425 in CO2/ CH4 on the gas separation, BTDA-CADA1-450, more than the upper limit of 2008 Robeson, separation in 400 and 425 DEG C heat treated membrane of CO2/CH4 gas are also in the vicinity of Robeson on the upper limit of 1991.4. through polycondensation reaction was successfully prepared with linear microporous polymer PIM-1, and through FTIR, 1H-NMR, TGA, BET and water contact angle and a series of characterization tests proved high specific surface area and hydrophobic properties were successfully prepared and polymers possess. Concentration and spinning parameters of polymer solution were prepared via electrospinning The fiber diameter is 1.7 m, PIM-1 fiber membrane smooth, uniform, mainly for the application of.5. oil-water separation and adsorption to the super hydrophobic membrane fiber - superoleophilic obtained by doping the hydrophobic nanoparticles POSS to fiber surface modification, when the POSS content reached 40wt%, was prepared by water contact angle 155 degrees,.40wt%PIM-1/POSS fiber membrane fiber membrane oil contact angle is 0 DEG - super hydrophobic superoleophilic can separate a series of immiscible oil-water mixture, the separation efficiency is as high as 99.95%, and can also be separated with surfactant and emulsion of oil-water mixture containing surface active agent is not stable, high separation efficiency 99.97%. after repeated use, water contact angle and small flux fiber membranes. In the harsh environment of swelling and ultrasonic, POSS particles remain in the surface of the fiber, the fiber membrane still exhibits super hydrophobic good performance of.6 Through the adsorption removal of organic solvent in the oil soluble dye to achieve organic solvent recovery. BET test data comparison of PIM-1 dense membrane and fiber, fiber surface area, average pore size, pore volume and pore are higher than that in the dense membrane, the adsorption process, the adsorption rate of fiber the higher dense film many times. The pseudo first order and pseudo two adsorption kinetic adsorption process, found that the adsorption kinetics of dense membrane and fiber are in line with the pseudo two order kinetics and the adsorption process of particle diffusion was the rate controlling step of adsorption mechanism of.PIM-1 oil soluble dyes for pi pi electron attractive interactions in between. Which adsorbed dye molecules to the pi electron cloud density of electrons is stronger, the adsorption quantity is high by.7. of PIM-1 fibers with different concentrations of sodium hydroxide hydrolysis, preparation of surface carboxyl group containing water solution fiber Wei. Because the PIM-1 surface after hydrolysis containing a carboxylic acid group, the hydrophilic material has greatly increased, on the other hand, because the carboxyl after ionization negative charge, can promote the adsorption of cationic dyes in aqueous solution is positively charged. The saturated adsorption capacity of methylene blue, safranin O and methyl violet respectively. 424.80364.29, and 317.26 mg.g-1, however, the saturated adsorption capacity of methyl orange was 42.38mg.g-1, compared with the saturated adsorption capacity of three cationic dyes, adsorption of anionic dye methyl orange is very low, so after hydrolysis of PIM-1 has the ability of adsorption of anionic and cationic dye solution selectivity. Analysis of dye solution respectively. With different pH value and solid UV, PIM-1 dye adsorption mechanism after hydrolysis of the main object of the interaction between the electron and the adsorption process makes the electron density both changed Due to the negative electricity on the surface of PIM-1 after hydrolysis, it can also adsorb heavy metal ions in aqueous solution, and the adsorption capacity for Pb2+ and Cu2+ is 41.2 and 16.9 mg.g-1. respectively.

【学位授予单位】：北京化工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ051.893

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