Preparation and structural control of polyphenylene sulfide porous fibers via thermally induced phase separation method

The porous fibers are expected to be widely used in liquid filtration, environmental protection, and catalyst carrier field. Polyphenylene sulfide (PPS) porous fiber was prepared using polyethersulfone (PES) as pore-forming agent by a thermally induced phase separation method. The rheological behaviors, crystallization, compatibility of the PPS/PES blending resins and fibers were characterized by the tests of high pressure capillary rheology, differential scanning calorimetry, and dynamic thermodynamic analysis, and so on; meanwhile, the structure and properties of PPS porous fibers were studied through the tests of continuity, scanning electron microscope, mercury injection, and mechanical properties. The results shown that the pore structure of porous PPS fibers can be regulated by controlling the PES content. In the spinning process, the higher winding speed (R = 300 ~ 400) and the larger PES content (60%) are more conducive to the formation of an interpenetrating structure of PES in the blend system. After the extraction of PES, PPS fibers with PES contents of 30% and 40% formed pore structure with uniform shape and size. Nevertheless, a high PES fraction of 60% leads to the collapse of the pore structure, resulting in serious structural damage. The porous fiber with controllable pore dimension is obtained by selecting proper ratio of polymers and appropriate spinning conditions.     

界面溶蚀法制备多孔磺化聚苯乙烯/壳聚糖微球及其Cr~(3+)吸附研究

采用固/液界面溶剂溶胀诱导相分离法,对磺化聚苯乙烯(SPS)和表面负载有生物相容性的壳聚糖(CS)的核壳型SPS/CS两种微球进行溶蚀,制备出具有多孔结构的SPS和SPS/CS微球。研究发现,溶剂类型和醇水比是影响多孔聚合物微球形态的主要因素。利用透射电镜(TEM)对多孔微球的结构进行表征,通过紫外可见分光光度计(UV-Vis)测定SPS/CS多孔微球在室温环境下对Cr3+的吸附行为。结果表明,界面溶蚀法可制备出形貌均一的多孔聚合物微球,其对Cr3+吸附量明显优于实心结构的微球。     

泡沫分离法制备聚苯乙烯多孔微球

以一种新型、简单、高效的溶剂挥发法制备不同孔形态和粒径分布的聚苯乙烯微球。该方法利用机械搅拌和升温过程中溶剂挥发产生的泡沫,将油相液滴夹带进入泡沫相,使溶剂在气相中迅速挥发,诱导聚合物与非良溶剂发生相分离成孔。结果表明：随着聚合物与致孔剂用量比减小,微球结构形态由多孔演变到中空结构;聚乙烯醇（PVA）质量分数由1%增大至3%时,微球的平均粒径由52μm±23μm减小至23μm±20μm及转速由300r/min增大至700r/min时,微球粒径由107μm±40μm减小到45μm±20μm,但由于产生的泡沫量和泡沫形态不同影响了溶剂的挥发过程,故得到微球的多孔形态不同,增大PVA浓度得到的微球表面孔数目较少、孔径较大,而增大转速得到的微球孔数目较多。此外,该方法在油水相比≥1时,在泡沫中也能得到稳定规则的多孔微球,而传统的在水相中引发相分离的方法因水相无法完全分散油相,故无法成球。     

Preparation of monodispersed porous polyacrylamide microspheres via phase separation in microchannels

We report on the formation of polyacrylamide (PAM)/polyethylene glycol (PEG) core/shell droplets in a microchannel via the polymerization-induced phase separation of an acrylamide (AM)/PEG aqueous system. Monodispersed porous PAM microspheres were prepared from the PAM/PEG core/shell droplets, and we examined the effects of experimental parameters on the phase separation process and on the particle size and pore structure of the resulting PAM microspheres. PAM microspheres could be readily obtained with adjustable particle sizes and porosities by altering the PEG and crosslinker contents and by using PEG with different molecular weights. The relation between the swelling value and porosity is correlated.     

Preparation and characterization of cellulose triacetate membranes via thermally induced phase separation

A series of cellulose triacetate (CTA) membranes were prepared via thermally induced phase separation (TIPS) process with dimethyl sulfone (DMSO2) and polyethylene glycol (PEG400) as a crystallizable diluent and an additive, respectively. The phase separation behavior of CTA/DMSO2/PEG400 ternary system was investigated in detail by optical microscopy, differential scanning calorimetry and wide angle X‐ray diffraction. This ternary system dynamically undergoes solid‐solid phase separation and thus the CTA membranes possess cellular, lacy, plate‐, or even ellipse‐shaped pores. However, we can modulate the pore structure, porosity, water flux, and mechanical properties of the membranes by varying polymer concentration, composition of the mixed diluent, and cooling condition. Due to the intrinsic hydrophilicity, the prepared CTA membranes have better antifouling property than polysulfone membranes. These porous membranes were used as supports to fabricate thin‐film composite forward osmosis (FO) membranes, which show good water permeability and selectivity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44454.     

Fabrication of cellulose acetate ultrafiltration membrane with diphenyl ketone via thermally induced phase separation

With diphenyl ketone as diluent, cellulose acetate (CA) ultrafiltration (UF) membrane with a bicontinuous structure was prepared via thermally induced phase separation (TIPS) method. The liquid–liquid phase separation region of CA/diphenyl ketone system was measured and the maximum corresponding polymer concentration was approximately 53 wt %. The effects of polymer concentration, coarsening time and coarsening temperature on the morphologies, and mechanical properties of CA membranes were investigated systematically. As the polymer concentration increased from 15 to 30 wt %, the bicontinuous structure could be obtained and the tensile strength of CA membranes increased from 3.92 to 30.17 MPa. With the increase of coarsening time, the thickness of dense skin layer and the asymmetry of cross‐section reduced. However, excess coarsening rendered the membrane morphology evolved from a bicontinuous structure to a cellular structure. When the coarsening time was 5 min, the bicontinuous structure in cross‐section showed good interconnectivity and the dense skin layer exhibited a thin thickness of 2 μm. The fabricated CA hollow fiber UF membrane exhibited a high tensile strength of 31.00 MPa and rejection of 96.10% for dextran 20 kDa. It is indicated that diphenyl ketone is a competitive diluent to prepare CA membranes with excellent performance via TIPS. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42669.     

载阿霉素聚乳酸多孔微球的表征及释药性能

以阿霉素（DOX）为小分子化学药物模型,采用吸附法对聚乳酸（poly-L-lactide,PLLA）多孔微球进行载药,采用场发射扫描电子显微镜（FE-SEM）、傅里叶变换红外光谱（FTIR）、X射线衍射（XRPD）及差示扫描量热（DSC）对DOX-PLLA复合微球的形貌粒径及空气动力学性能、药物及材料的理化性能、载药性能进行表征,并且研究了其载药量、包封率和体外释放性能。结果表明,不同载药量之间的PLLA多孔微球粒径并无显著差异,均具有良好的空气动力学性能,适合肺部可吸入给药的条件;化学组成未见明显改变,物理结构由结晶态变为无定形态;随载药量的增加（2.9%,4.0%,4.6%）,包封率逐渐降低（56%,51%,44%）;药物的体外释放与原料药相比具有一定的缓释效果,最长释放时间可达5天,表明DOX-PLLA复合微球有望作为缓释制剂用于肺部给药。     

Fabrication of highly porous mullite microspheres via oil-drop molding accompanied by freeze casting

Porous mullite microspheres with a highly open porosity and average diameter of more than 800 µm were fabricated via an oil-drop molding method accompanied by a freeze casting process. After sintering, a highly porous structure was formed due to interlocking whisker-shaped mullite grains and formation of interconnected skeletons during the freeze-casting process. Additionally, it was found that a high porosity and large pore size in the microspheres green bodies are favorable for the synthesis of mullite whiskers with high aspect ratio.     

肺部给药用高分子多孔微球的制备及改性研究进展

肺部给药作为一种非入侵式的给药方式,在蛋白质、多肽类药物的给药研究中具有很大的发展潜力。高分子多孔微球是最适合肺部给药的药物载体之一,本文首先阐述了高分子多孔微球的几种传统制备方法,分析了这些制备方法在不同的条件下存在的优点及缺点。随后本文针对传统的高分子多孔微球制备条件难以单独控制,药物不能有效包封等问题,对近年来研究者们为了提高多孔微球的性能对其进行的物理化学改性进行了综述并提出了观点。最后对肺部给药用高分子多孔微球不同的制备方法的相互结合以及在生物医学领域的应用价值进行了展望。     

高内相乳液聚合制备多孔整体聚合物的孔结构调控与表征

以苯乙烯、二乙烯基苯为原料,山梨糖醇酐单油酸酯Span80为乳化剂,过氧化苯甲酰(BPO)为引发剂,氯化钙水溶液为分散相,通过高内相W/O乳液体系制备Poly HIPE。探讨了不同油水比、乳化剂用量和二乙烯基苯含量对聚苯乙烯(PS)/二乙烯基苯DVB型Poly HIPE孔结构、密度和比表面积的影响。结果表明,随着油水比的减小,乳液稳定性增强,Poly HIPE孔径变大,贯通孔数量增多;增加乳化剂用量或单体中二乙烯基苯比例,Poly HIPE的孔径变小,贯通孔数量增多。除此之外,研究还发现油水比的减小使得Poly HIPE的表观密度和比表面积降低,而提高乳化剂用量和二乙烯基苯比例可提高Poly HIPE的表观密度和比表面积。     

The formation of the S‐shaped edge‐on lamellae on the thin porous polylactic acid membrane via phase separation induced by water microdroplets

Biodegradable polymers have received increased attention due to their potential application in the medicine and food industries; in particular, poly(lactic acid) (PLA) is a primary biopolymer because of its excellent biocompatibility and absorbability features. In this study, a porous PLA membrane was fabricated by phase separation using water microdroplets produced by an ultrasonic atomizer as a coagulation bath. The formation of S‐type clusters was attributed to the slow exchange rate between solvent and coagulant, which provided time for the movement of polymer molecules. The effect of preparation conditions on the structure of S‐type clusters, including polymer concentration in solution and ambient temperature was investigated. The PLA porous membrane prepared from water micro‐droplets with different morphology compared with the sample fabricated from distilled water has potential application in fields of tissue engineering and artificial organ generation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43355.     

Fabrication,drug delivery kinetics and cell viability assay of PLGA-coated vancomycin-loaded silicate porous microspheres

Porous ceramic microspheres are a desirable substance for bone tissue reconstruction and delivery applications. This study focuses on Mg–Ca silicate microspheres encapsulated in biodegradable poly (lactic-co-glycolic acid) (PLGA) to serve as a biocompatible carrier for the controlled release of vancomycin hydrochloride. In this regard, diopside (MgCaSi₂O₆), bredigite (MgCa₇Si₄O₁₆), and akermanite (MgCa₂Si₂O₇) powders were synthesized by sol-gel and subsequent calcination methods. Then, porous akermanite, diopside and bredigite microspheres of 700–1000 μm in diameter were fabricated by using carbon porogen, droplet extrusion and sintering, then loaded with the drug and eventually coated with PLGA. The bare microspheres showed a considerable burst release mode of the drug into a physiological medium, whereas PLGA coating of the microspheres reduced the burst release level. To investigate effective mechanisms governing in the drug release from the carriers, the contribution of burst, degradation, and diffusion was analyzed by the sequential quadratic programming algorithm method. It was found that the relative contribution of diffusion to bioresorption is ranked as diopside > akermanite > bredigite, whereas PLGA coating dominates the diffusion mechanism. The dental pulp stem cells cytocompatibility MTT assay of the microspheres also showed that the drug loading deteriorates but PLGA coating improves the cell biocompatibility significantly. Comparatively, the biocompatibility of the PLGA-coated microspheres was ranked as akermanite > diopside > bredigite, as a result of a compromise between the release of the constituting ions of the ceramic carriers and vancomycin molecules. It was eventually concluded that PLGA-coated Mg–Ca silicate microspheres are promising candidates for drug-delivery bone tissue engineering and dental bone grafting applications.     

聚乳酸多孔微球的制备及其表征

以聚乳酸（PLLA）/四氢呋喃（THF）为淬火溶液,无其他添加剂条件下,通过低温淬火、萃取、洗涤和干燥得到直径为30.92μm±1.55μm的PLLA多孔微球,多孔微球由直径为0.34μm±0.06μm向外辐射的纤维组成。偏光显微镜表明多孔微球为球晶结构。XRD结果表明,多孔微球属于α晶型,晶粒尺寸大小为17.25nm。DSC结果表明,PLLA多孔微球的结晶度为36.05%。与熔融挤出造粒得到PLLA原料（结晶度小于10%）相比,低温淬火得到的多孔微球的结晶度大大提高。N₂吸附-脱附结果分析表明,多孔微球的平均孔径和孔体积分别为42.92nm和0.1135cm³/g,大部分为大孔和介孔结构,比表面积和孔隙率分别为14.18cm²/g和93.15%。采用等温DSC模拟低温淬火过程研究了PLLA在THF溶液中结晶动力学,利用Avrami方程得到Avrami指数n平均值为2.29,说明PLLA在THF溶液中为异相成核和三维生长。     

Factors controlling surface morphology of porous polystyrene membranes prepared by thermally induced phase separation

A special device for preparing porous polymer membranes through a thermally induced phase separation (TIPS) process was designed and machined; it included a solution container, a membrane‐forming platform, a coldplate, a temperature‐decreasing system and a temperature‐supervising system. Polystyrene was selected as the model polymer from which to prepare porous membranes using the device due to its better understood TIPS and good biocompatibility with cells. The major factors controlling surface morphology and cell size, ie volume fraction of polystyrene (ϕ₂), quench rate and solvent‐removing methods, were studied. Fixing the coldplate temperature, when ϕ₂ is as low as 0.045, provokes the formation of round pores on both the bottom and top surfaces of the membrane; when ϕ₂ = 0.16 no pores are formed on either surface; when ϕ₂ = 0.087 pores form on the top surface, but not on the bottom surface. When ϕ₂ = 0.087 the cell size is very small or no pores are formed on the bottom surface, whereas the top surface shows a regular decrease of the pore sizes and an increase of the pore number and pore area, along with a decrease of the coldplate temperature. The side near the coldplate is dense, and the dense layer aligns along the coldplate, while the side away from the coldplate is like a porous foam, the shape of which is isotropic and the surfaces are interconnected with each other three dimensionally. On the top surface of a membrane obtained by ethanol extraction, the cell size is enlarged and the cell number reduced, but the surface morphology and the whole area remained almost the same when compared to samples obtained by freeze drying in the same membrane‐forming conditions. The isotropic, uniformly distributed and round pores suggest that the mechanism of phase separation is a spinodal liquid–liquid decomposition under our research conditions. © 2000 Society of Chemical Industry     

Simple method for preparation of thermally expandable microspheres of PMMA encapsulating NaHCO3 via thermally induced phase separation

Thermally expandable microspheres (TEMs) employing poly(methyl methacrylate) (PMMA) as shell and sodium bicarbonate (NaHCO₃) as core were prepared by a simple method of thermally induced phase separation (TIPS). The addition of NaHCO₃ improved the foaming properties of TEMs. The effects of preparation parameters on the morphology, amount of encapsulated NaHCO₃, and foaming properties of TEMs were studied; the parameters investigated included the quench rate, the molecular weight (M_w) and amount of PMMA, and the amount of NaHCO₃. The results show that when 0.5 g of PMMA 50k, 3 g of NaHCO₃, and 50 g of ethanol were used, with quenching temperature at 0 °C, the TEMs were fully spherical and the maximum expansion volume of TEMs was about 3.8 times the original volume. The expansion volume of TEMs increased with increasing amount of encapsulated NaHCO₃, and the foaming onset temperature and temperature of complete bursting of TEMs were related to the M_w of PMMA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46179.     

Fabrication and characterization of chlorinated polyvinyl chloride microporous membranes via thermally induced phase separation process

Microporous chlorinated polyvinyl chloride (CPVC) membranes were prepared via thermally induced phase separation process for the first time using diphenyl ether (DPE) as diluent. The CPVC/DPE blends exhibit upper critical solution temperature (UCST)‐type phase behavior, which undergoes liquid‐liquid phase separation followed by sol‐gel transition during cooling process. Therefore, the resulting CPVC membranes presented symmetric morphology with uniformly distributed cellular pores. The cloud point (liquid‐liquid phase separation temperature) decreased with increasing CPVC content, while the sol‐gel transition temperature showed an opposite trend. Both the growth rate of diluent‐rich phase droplets and the gelation rate of the CPVC/DPE blends increased by decreasing CPVC concentration or cooling rate, leading to an increase of the pore size in the final membranes. Results of water permeation tests confirmed that the water flux of the membranes have a significant dependence on their porosity and pore size, that is the water flux increased with the increase of porosity and pore size. Moreover, the CPVC microporous membranes prepared by the TIPS process showed a high mechanical strength and excellent acid/alkali resistance, which has presented a great potential for application in the fields of water and wastewater treatment. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44346.     

相分离制备聚己内酯纳米纤维支架的工艺探讨

以二氧六环/水为溶剂体系采用相分离方法首次成功制备了高孔隙率、具有纳米纤维状结构的聚己内酯（PCL）支架,并且支架是以球体为结构单元的基体。文中主要探讨了陈化温度和溶剂比例对于球状纳米纤维结构支架形成的影响,太低（-40 ℃）或太高的陈化温度（≥8 ℃）均不利于PCL纳米纤维结构的出现,只有适宜的实验温度才可以得到纳米纤维球状基体。同样,非溶剂比例越大越不利于纳米纤维球状基体的形成。     

Preparation of cellulose triacetate aerogel via non-solvent impacted thermally induced phase separation for oil absorption

The oil spill has caused significant attention on a global scale due to its damage to the environment and the economy. The development of economically and ecologically friendly oil sorbent materials has important meaning for the oil spill concern. In this work, we explored the non-solvent impacted thermally induced phase separation (NITIPS) method to prepare the cellulose triacetate aerogel (CA) with low density (6.4–40.5 mg/cm³), high porosity (96.9–99.5%), large water contact angle (>129°) and high specific surface area (193–573 m²/g) as the oil sorbent material. The oil absorption capacity of CA with vegetable oil and vacuum pump oil reached 80.8 g/g and 38.9 g/g, respectively, consistent with Fick's law of diffusion. Moreover, the NITIPS method provided simpler process and controlled the shape of CA compared with the traditional thermally induced phase separation method. This study proved that the CA prepared by NITIPS methods played an important role as a potential oil absorption solids in the field of oil spill and organic chemical leakage.     

Formation of porous poly(ethylene‐co‐vinyl alcohol) membrane via thermally induced phase separation

Crystalline poly(ethylene‐co‐vinyl alcohol) (EVOH) membranes were prepared by a thermally induced phase separation (TIPS) process. The diluents used were 1,3‐propanediol and 1,3‐butanediol. The dynamic crystallization temperature was determined by DSC measurement. No structure was detected by an optical microscope in the temperature region higher than the crystallization temperature. This means that porous membrane structures were formed by solid–liquid phase separation (polymer crystallization) rather than by liquid–liquid phase separation. The EVOH/butanediol system showed a higher dynamic crystallization temperature and equilibrium melting temperature than those of the EVOH/propanediol system. SEM observation showed that the sizes of the crystalline particles in the membranes depended on the polymer concentration, cooling rate, and kinds of diluents. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2449–2455, 2001     

泡沫相相分离制备多孔聚合物微球连续化工艺

采用在泡沫相进行溶剂挥发的方法，连续、高效制备聚甲基丙烯酸甲酯-丙烯酸丁酯[P(MMA-BA)]共聚物多孔微球。采用自制的连续化反应装置，在一定搅拌速率和反应温度下，向反应器连续加料，在出口处连续收集溢出的泡沫并进行消泡、分散，再经洗涤、过滤、干燥得到多孔聚合物微球。重点研究了油相进料速率、反应温度、搅拌速率、聚乙烯醇用量(PVA浓度)对平均泡沫溢出速率、微球收率、微球粒径以及多孔形态的影响规律。结果表明：在反应温度为45℃，搅拌速率为500 r/min，油相溶液进料速率为30 g/min，PVA浓度为1.0%(质量)，油相溶液中P(MMA-BA)∶二氯甲烷(DCM)∶正庚烷(HT)=10∶53∶6(质量比)的工艺条件下，聚合物微球的收率高达92%，平均粒径为130 μm，P(MMA-BA)微球球形饱满，呈多孔结构。