聚合物PPES/PPEK/PPESK-NMP-H2O三元体系的相行为研究(Ⅰ)浊点与饱和吸附量测定

采用浊点滴定法实验测定了新型成膜聚合物杂萘联苯聚芳醚砜(PPES)、杂萘联苯聚芳醚酮(PPEK)和杂萘联苯聚芳醚砜酮(PPESK)的N-甲基吡咯烷酮(NMP)溶液分别在3种不同温度(25,50和75℃)下用水滴定时的浊点数据.并用线性浊点方程对所得实验结果进行了参数回归,线性度甚佳.采用平板刮膜法制备了PPES,PPEK和PPESK的致密膜,并用称重法测定了3种聚合物膜对水的饱和吸附量,进而根据Flory-Rehner理论计算了聚合物与沉淀剂水之间的Flory-Huggins相互作用参数.为进一步理论计算PPES,PPEK和PPESKNMP-H2O的三元相图提供了基础数据.     

SPPESK/SPEEK共混质子交换膜的制备与性能

以耐溶胀性能较好的磺化聚芳醚砜酮(SPPESK)和吸水性较强的磺化聚醚醚酮(SPEEK)为原料,制备了SPPESK/SPEEK共混质子交换膜。考察了共混膜的水吸收率,水溶胀度,甲醇水溶胀度,甲醇渗透率及质子传导率和力学性能。80℃时,共混膜具有适当的水吸收(101%)和溶胀度(34%),较低的甲醇水溶胀度(20%),较高的质子传导率(0.212 S/cm),与SPPESK膜相比,质子传导率提高了18%。SPEEK的加入改善了共混膜的柔韧性,断裂拉伸应变从16.48%提高到30.43%。     

磺化含侧苯基杂萘联苯聚芳醚砜膜材料的制备与性能

以含侧苯基杂萘联苯聚芳醚砜(PPES-Os)为原料,通过非均相法制备磺化含侧苯基杂萘联苯聚芳醚砜(SPPES-Os).通过核磁共振与红外光谱表征了SPPES-Os的结构,测试了SPPES-Os的离子交换容量(IEC)、溶解性,采用热失重分析法对SPPES-Os的热稳定性进行了分析.采用溶液浇铸法将SPPES-Os制成均质膜,考察了IEC对均质膜的吸水率、溶胀率、接触角、水蒸气吸附性以及水蒸气渗透性能的影响.结果表明,随着IEC增加,膜的吸水率、水蒸气吸附量和水蒸气渗透速率增加,而接触角降低;SPPES-Os膜在25℃时吸水率在9%以上,48℃时水蒸气渗透速率高于7.53×10~(-3) g/(cm~2·h).     

杂萘联苯聚芳醚酮含量对钒电池用离子交换膜性能的影响

将含溴甲基杂萘联苯聚醚酮与杂萘联苯聚芳醚酮(PPEK)以不同的比例进行共混,采用溶液浇铸的方法得到一系列基膜,然后将其浸泡在三甲胺溶液中进行胺化处理,得到季胺化杂萘联苯聚芳醚酮离子交换膜(QBPPEK/PPEK)。测试了QBPPEK/PPEK的离子交换容量(IEC)、吸水率、溶胀率、面电阻、钒渗透系数和微观结构。随着PPEK含量的增加,QBPPEK/PPEK膜的IEC、吸水率和钒渗透系数减小而面电阻上升。QBPPEK/PPEK膜具有较好的阻钒性能,其电流效率均大于Nafion115。当PPEK含量为10%时,QBPPEK/PPEK膜单电池的能量效率达到88.9%。PPEK的加入可以有效的提高QBPPEK/PPEK膜的氧化稳定性。     

杂萘联苯共聚醚砜的磺化

以浓硫酸为磺化剂对杂萘联苯共聚醚砜进行磺化改性,合成了一系列不同磺化度的磺化杂萘联苯共聚醚砜(SPPBES)。考察了硫酸浓度、磺化反应温度和反应时间、杂萘联苯共聚醚砜与硫酸的质量体积比对产物磺化度的影响。随着硫酸浓度增加、磺化反应温度升高、反应时间的延长,SPPBES的磺化度增大。调节磺化反应条件,制得了磺化度在0.37～1.04之间的SPPBES。利用FT-IR、1H-NMR和TGA对SPPBES进行了表征,测试了SPPBES的含水率和溶胀率。     

钒电池用含吡啶基杂萘联苯聚芳醚酮隔膜的研制

以含二甲基杂萘联苯聚芳醚酮为原料,通过控制溴化条件,得到了含溴甲基杂萘联苯聚芳醚酮,与吡啶反应得到可溶解的含吡啶基杂萘联苯聚芳醚酮(Py-PPEK),通过溶液浇铸法制得了含吡啶基阴离子交换膜。考察了离子交换容量(IEC)对Py-PPEK膜基本性能及电池性能的影响。研究结果表明,随着IEC的增加,Py-PPEK膜的吸水率和溶胀率增加,钒离子渗透系数和面电阻减小,钒电池的电流效率、电压效率和能量效率提高。在电流密度为40 mA/cm~2时,Py-PPEK30(IEC=0.41 mmol/g)膜的电流效率达到95.5%,优于Nafion115膜。     

无机添加剂对磺化杂环共聚醚砜复合膜性能的影响

以磺化联苯型杂萘联苯共聚醚砜(SPPBES)为涂层材料,分别加入LiCl、NaCl、KCl作为无机添加剂配制浸涂稀溶液,在联苯型杂萘联苯共聚醚砜(PPBES)超滤底膜上,采用涂覆方法制备磺化杂萘联苯共聚醚砜复合纳滤膜(SPPBES-LiCl、SPPBESNaCl和SPPBES-KCl)。考察了无机添加剂对复合膜的分离性能的影响,复合膜对不同无机盐的脱盐率顺序均为Na_2SO_4NaClMg SO_4MgCl_2,表现出荷负电纳滤膜的分离特征,以LiCl为添加剂所制备的SPPBES-LiCl复合纳滤膜的脱盐率最高,通量最小。研究了复合膜的耐热性能和耐氧化性能,当操作温度从20℃升至95℃时,SPPBES-LiCl复合膜的通量由46 L·m~(-2)·h~(-1)增加到130 L·m~(-2)·h~(-1),而脱除率下降约3%,相比于SPPBES-NaCl和SPPBES-KCl,SPPBES-LiCl复合膜分离性能随操作温度升高变化最小。在0.2 g·L~(-1)的NaCl O溶液中浸泡8 d,SPPBES-LiCl复合膜通量增大2%左右,而SPPBES-NaCl与SPPBES-KCl的通量增幅小于8%;相比于SPPBES-NaCl和SPPBES-KCl膜,SPPBES-LiCl复合膜具有更好的耐氧化稳定性。此外,3种磺化杂萘联苯共聚醚砜复合纳滤膜均表现出了较好的耐酸碱稳定性。     

含醚键双二氮杂萘酮结构聚芳醚腈砜的合成与性能

文中以含醚键双二氮杂萘酮结构化合物4,4’-双(氧基(1,4-苯撑))-双二氮杂萘-1(2H)酮-二苯醚(OBDHPZ)为类双酚单体,与4,4’-二氟二苯砜(DFS)和2,6’-二氟苯腈(DFBN)进行高温溶液缩聚反应,通过调节聚合物分子主链中砜基和氰基等的含量,合成了一系列不同腈砜比的含醚键双二氮杂萘酮联苯结构聚芳醚腈砜树脂(PBPENS),其N-甲基吡咯烷酮(NMP)溶液在25℃的特性黏度为0.63～0.90 dL/g。通过红外光谱、核磁共振氢谱和广角X射线衍射仪表征了所合成聚芳醚腈砜的结构;通过差示扫描量热仪和热失重分析仪分析了该类聚芳醚腈砜的热性能,聚合物的玻璃化转变温度(T_g)在322～325℃,5%热失重温度(T_d5%)在485～500℃。该类聚合物在常温时可溶解于NMP、N,N-二甲基乙酰胺(DMAc)、氯仿等极性非质子有机溶剂;采用溶液浇筑法制备了含醚键双二氮杂萘酮结构聚芳醚腈砜薄膜,薄膜的拉伸强度可以达到56～65 MPa。     

甲酰胺对PES及PPESK相转化非对称膜结构与性能的影响

采用凝胶相转化法,以聚醚砜(PES)、杂萘联苯聚芳醚砜酮(PPESK)为膜材料,N,N-二甲基乙酰胺(DMAc)、N-甲基吡咯烷酮(NMP)为溶剂,通过改变铸膜液中非溶剂添加剂甲酰胺的含量,在平板刮膜机上制备了一系列超滤膜。考察了甲酰胺对铸膜液黏度、膜结构和性能的影响,对PES/DMAc和PPESK/NMP铸膜液体系中甲酰胺的作用规律进行了研究。     

磺化聚芳醚酮砜/PVA复合质子交换膜的制备与性能

为了进一步提高质子交换膜在中高温时的质子导电率,文中以高磺化度的磺化聚芳醚酮砜(SPAEKS)和聚乙烯醇(PVA)为原料,通过溶液共混法制备了PVA不同含量的磺化聚芳醚酮砜/PVA复合膜。通过对复合膜的性能测试发现,PVA的引入提高了膜的热稳定性、吸水率和保水能力。而且SPAEKS/PVA复合膜的质子传导率高于SPAEKS膜,在80℃时,复合膜的质子传导率都在0.07 S/cm以上,能够满足中高温质子交换膜燃料电池的使用要求。     

化学交联法在质子交换膜制备中的应用

化学交联是提高质子交换膜性能的一种有效方法。交联质子交换膜具有较低的水溶胀性、甲醇渗透性,以及较高的热、力学稳定性。使用化学交联法制备质子交换膜时,通常采用交联聚合物磺化法、磺化聚合物交联法和共混聚合物交联法等三种方法。采用不同方法交联时,交联活性点的选取各不相同,制备的交联质子交换膜性能也有差异。深入研究交联程度、离子交换容量、交联剂种类等不同制备条件对交联膜的微观结构及性能的影响,才能使交联质子交换膜的综合性能得到优化。     

Poly(2-hydroxyethyl methacrylate) wound dressing containing ciprofloxacin and its drug release studies

An improved wound dressing with a long-term drug diffusion-efficacy has been developed by UV-radiation technique. It involves incorporation of ciprofloxacin (CIP), at the concentration of 0.5–2.0% (w/v), into a water mixture of 2-hydroxymethacrylate (HEMA) monomer, benzoin isobutyl ether (BIE) initiator and different content of ethylene glycol dimethacrylate (EGDMA) cross-linker. Increasing the concentration of EGDMA would reduce the releasing ratio of CIP from pHEMA. T_1/2 is increased from 2.64 to 45.67 h when the EGDMA is added from 1 to 8%. In the ranges of , the n value of 1%CIP-pHEMA membranes is increased from 0.48 to 0.81. It indicates that the mechanism of drug release falls between the Fickian and Case II diffusion model. The antibacterial activity of the drug impregnated into the membrane was evaluated by in vitro drug kinetic agar plate method. Higher concentration of EGDMA, up to 8% of the cross-linker, extends the drug release. Comparison with the drug-soaked membranes, the newly synthesized 1% CIP-pHEMA membrane (cross-linked with 4% EGDMA) sustains the release of the entrapped drug and maintains the antibacterial activity up to 12 days.     

超临界二氧化碳中N-异丙基丙烯酰胺与二乙二醇二甲基丙烯酸酯的交联聚合

采用超临界二氧化碳（scCO2）沉淀聚合法,在不添加高分子表面活性剂及共溶剂的前提下,以AIBN为引发剂,二乙二醇二甲基丙烯酸酯为交联剂,成功制备了交联的聚（N-异丙基丙烯酰胺）温度敏感型微凝胶;通过扫描电镜（SEM）、差示扫描量热分析（DSC）等方法对聚合物的微观形貌进行了表征,测定了微凝胶的相转变温度,同时也考察了...     

Influence of cross-linking density on swelling and estradiol permeation of chitosan membranes

Chitosan membranes were obtained by a casting/solvent evaporation method and cross-linking with sodium tripolyphosphate. The effect of cross-linking time was studied and the cross-linked membranes were characterized with respect to equilibrium water content, sodium content, IR spectroscopy and permeability to a model drug (Estradiol). Sodium content increased with increasing cross-linking time. Equilibrium water content was higher in the membrane with the lowest cross-linking time. This membrane also showed a higher flux of Estradiol compared with the other which exhibited an increment in equilibrium water content and flux of Estradiol with the increase in cross-linking duration. These dissimilar results could be explained by a significant correlation between the hydrophilicity of the membrane and the hydrophobicity of Estradiol.     

Cross-linking by 1-ethyl-3- (3-dimethylaminopropyl)-carbodiimide (EDC) of a collagen/elastin membrane meant to be used as a dermal substitute: effects on physical, biochemical and biological features in vitro

Next to in vitro-cultured autogeneic keratinocytes for the restoration of epidermis, a suitable dermal matrix is a mandatory component of an artificial skin substitute for the permanent covering of full thickness skin defects. In our model a xenogeneic membrane, consisting of processed native collagen and elastin of porcine origin is meant to serve as a template for the formation of a neo-dermis. In order to improve the resistance of this matrix against enzymatical degradation, we cross-linked it by using the carbodiimide 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) together with N-hydroxysuccinimide. Chemical cross-linking by these agents at two different degrees (shrinkage temperatures 63 °C and 81 °C) had no relevant effect on mechanical features or water-uptake capacity. The time needed for enzymatic digestion was increased by cross-linking. Concerning growth and spreading of fibroblasts and keratinocytes on and within the structure of this membrane, we did not observe a difference between cross-linked and non-cross-linked material (shrinkage temperature 48 °C). We therefore expect that cross-linking by EDC is an effective means to control the degradation of the collagen/elastin membranes in vivo without a significant influence on their biocompatibility. © 2001 Kluwer Academic Publishers     

Mass spectrometry identifiable cross-linking strategy for studying protein-protein interactions

A new mass spectrometry identifiable cross-linking strategy has been developed to study protein-protein interactions. The new cross-linker was designed to have two low-energy MS/MS-cleavable bonds in the spacer chain to provide three primary benefits: First, a reporter tag can be released from cross-link due to cleavage of the two labile bonds in the spacer chain. Second, a relatively simple MS/MS spectrum can be generated owing to favorable cleavage of labile bonds. And finally, the cross-linked peptide chains are dissociated from each other, and each then can be fragmented separately to get sequence information. Therefore, this novel type of cross-linker was named protein interaction reporter (PIR). To this end, two RINK groups were utilized to make our first-generation cross-linker using solid-phase peptide synthesis chemistry. The RINK group contains a bond more labile than peptide bonds during low-energy activation. The new cross-linker was applied to cross-link ribonuclease S (RNase S), a noncovalent complex of S-peptide and S-protein. The results demonstrated that the new cross-linker effectively reacted with RNase S to generate various types of cross-linked products. More importantly, the cross-linked peptides successfully released reporter ions during selective MS/MS conditions, and the dissociated peptide chains remained intact during MS(2), thus enabling MS(3) to be performed subsequently. In addition, dead-end, intra-, and inter-cross-linked peptides can be distinguished by analyzing MS/MS spectra.     

Biocompatibility of chemically cross-linked gelatin hydrogels for ophthalmic use

Biocompatibility is a major requirement for the development of functional biomaterials for ophthalmic applications. In this study, we investigated the effect of cross-linker functionality on ocular biocompatibility of chemically modified gelatin hydrogels. The test materials were cross-linked with glutaraldehyde (GTA) or 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide (EDC), and were analyzed using in vitro and in vivo assays. Primary rat iris pigment epithelial cultures were incubated with various gelatin discs for 2 days, and the cellular responses were monitored by cell proliferation, viability, and pro-inflammatory gene and cytokine expression. The results demonstrated that the cells exposed to EDC cross-linked gelatins had relatively lower lactate dehydrogenase activity, cytotoxicity, and interleukin-1β and tumor necrosis factor-α levels than did those to GTA treated samples. In addition, the gelatin implants were inserted in the anterior chamber of rabbit eyes for 12 weeks and characterized by clinical observations and scanning electron microscopy studies. The EDC cross-linked gelatin hydrogels exhibited good biocompatibility and were well tolerated without causing toxicity and adverse effects. However, a significant inflammatory reaction was elicited by the presence of GTA treated materials. It was noted that, despite its biocompatibility, the potential application of non-cross-linked gelatin for local delivery of cell and drug therapeutics would be limited due to rapid dissolution in aqueous environments. In conclusion, these findings suggest ocular cell/tissue response to changes in cross-linker properties. In comparison to GTA treatment, the EDC cross-linking is more suitable for preparation of chemically modified gelatin hydrogels for ophthalmic use.     

聚乙烯醇/聚乙烯吡咯烷酮共混膜的制备和性能

制备了聚乙烯醇(PVA)、PVA/聚乙烯吡咯烷酮(PVP)与戊二醛交联的PVA/PVP膜用于渗透蒸发对乙酸乙酯/乙醇/水三元共沸体系脱水。采用傅立叶变换红外光谱(FT-IR),X射线散射(XRD)和扫描电镜(SEM)等对膜的物理化学结构及形貌进行了表征。考察了PVP含量、交联度对共混膜结构和亲水性的影响。考察了PVP含量、交联度和温度对PVA均质膜的分离性能和溶胀行为的影响。结果表明,交联的PVA/PVP共混膜对乙酸乙酯/乙醇/水有着优异的分离性能。     

Evaluation of cross-linked gelatin membranes as delivery carriers for retinal sheets

The delivery of intact sheet transplants to the subretinal space can prevent cell loss that is generally associated with the injection of cell suspensions or cell aggregates. The aim of this study was to develop chemically modified gelatin matrices that enhance the delivery efficiency and analyze whether the gelatin membranes cross-linked with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) can be considered as potential carriers for retinal sheets. The characteristics of EDC cross-linked gelatin membranes were determined by mechanical and in vitro degradation tests, melting point measurements, cell proliferation assays, cytokine expression analyses, and tissue delivery studies. Gelatin membranes without cross-linking and glutaraldehyde cross-linked gelatin samples were used for comparison. Results of this study indicated that introduction of cross-links is capable of rendering the gelatin network more stable against mechanical stresses and deformations as well as rapid hydrolysis during intraocular delivery of delicate tissue sheets. In comparison with the glutaraldehyde treated samples, the EDC cross-linked gelatin membranes showed a better degradation profile and a relatively higher cytocompatibility. In addition, after EDC cross-linking, the gelatin matrices having an acceptable melting point could be used for the fabrication of a sandwich-like carrier with a high transfer and encapsulation efficiency. These findings suggest that the cross-linking agent type gives an influence on delivery functionality of gelatin membranes. In summary, the EDC cross-linked gelatin is an ideal candidate for use as a carrier material in retinal sheet delivery applications.     

Preparation and characterization of poly(vinyl alcohol)/poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone)/nano-hydroxyapatite composite membranes for tissue engineering

In this paper, the poly(vinyl alcohol)/poly(epsilon-caprolactone)-PEG-poly(epsilon-caprolactone)/nano-hydroxyapatite (PVA/PCEC/n-HA) composite membranes were prepared by solution casting and evaporation methods. The effect of n-HA content on the properties of the composite membranes was studied. The PVA/PCEC/n-HA composite membranes were analyzed by FTIR spectroscopy, X-ray diffraction, water content measurement, contact angle, mechanical test, scanning electron microscopy. The results showed that the surface roughness of the composite membranes increased with the increase of n-HA contents. The n-HA content had obvious influence on the swelling ratio, tensile strength and elongation rate of the composite membranes. With the increase of n-HA contents, the swelling ratio increased at first, and then decreased; tensile strength and elongation rate decreased gradually. The PVA/PCEC/n-HA composite membranes may be applied in the field of tissue engineering.