The physicochemical and fire extinguishing performance of aqueous film-forming foams based on a class of short-chain fluorinated surfactants

Aqueous film-forming foams (AFFFs) are an important for fire extinguishing, and their key ingredient is fluorinated surfactant. In recent years, traditional long-chain fluorinated surfactants have been banned by most countries because of their persistence, bio-accumulation and toxicity. Therefore, increased attention has been paid to the research and development of short-chain fluorinated surfactants. As is well known, the introduction of hydrophilic or hydrophobic groups in a surfactant affects its surface activity, and therefore, the fire extinguishing performance of AFFFs. In this work, a series of short-chain fluorosurfactant-based AFFFs with different hydrophobic chain lengths were prepared. The physicochemical performance of mixed systems (fluorinated surfactant plus sodium hexanesulfonate), including surface activity, spreading ability, foam expansion, drainage time, and the fire extinguishing and burn-back performance of AFFFs were studied. The results show that the critical micelle concentration (CMC) and the surface tension (γ_CMC) at the CMC of mixed systems at 25°C are lower than 7.68 mmol/L and 16.51 mN/m, respectively. For mixed systems, the average spreading rate is more than 1.09 cm/s, the foam expansion is over 7.1, and the drainage time is greater than 3.28 min. The fire extinguishing time of AFFFs on fuels is less than 51 s while the burn-back time is more than 15.18 min. The results imply a potential application prospect of the short-chain fluorinated surfactants in AFFFs.     

高性能有机氟材料制备科学及应用进展

有机氟材料具有优异的热氧稳定性、耐化学腐蚀性、耐老化性、不黏性、电绝缘性以及极小的摩擦系数等特性，因此作为一种不可替代的材料广泛应用于高新技术产业。近年来高新技术产业发展对高性能有机氟材料的需求引发了学术界和工业界对氟材料的研究兴趣。依据本文作者的研究经历及有机氟材料的发展方向，本文介绍了氟树脂（新型含氟聚合物、电活性含氟聚合物、新型全氟磺酸聚合物、聚四氟乙烯3D打印）及氟橡胶（过氧化物硫化氟橡胶、耐低温氟醚橡胶、耐高温全氟醚橡胶、全氟聚醚基类玻璃橡胶）的制备科学及应用进展，特别阐述为了满足航空航天、能源、信息等高新技术产业需求发展的新一代高性能有机氟材料。本文也介绍了近期出现的聚四氟乙烯新成型技术及类玻璃氟橡胶。文章指出发展绿色环保和高效的高性能有机氟材料制备及成型加工方法是今后的发展方向。     

Cross‐Linked Fluorinated Poly(Aryl Ether) (C‐FPAE) Films: Preparation Strategy,Performance Study,and Low Dielectric Applications

The production of low dielectric materials that can be used in high temperature environments is the primary aim of this work. A cross‐linked structure is introduced into fluorinated poly(aryl ether) (named as FPAE) with high molecular weight (M_w, 140 000 g mol^?1) and linear molecular structure using nucleophilic substitution reaction at the ortho‐position of decafluorobiphenyl monomer units in the FPAE molecular chain. The curing temperature and curing time are optimized and the final conditions for the cross‐linking reaction in this study are determined to be 300 °C for 1 h. Moreover, the dielectric constant and dielectric loss of the C‐FPAE film respectively are 2.67 and 0.006 at 1000 Hz when 1 wt% of crosslinking agent is added, and the cross‐linked fluorinated poly(aryl ether) film shows excellent thermal stability (T_d(5%), 495 °C), dimensional stability, hydrophobic properties, and high storage modulus in high temperature environments. Such novel low dielectric material with excellent performances has important application value in the aerospace and the integrated electronics field.     

简捷水热法制备氟化石墨烯及其表征

氟化石墨烯是一种石墨烯衍生物,在润滑材料、电子器件等领域具有广阔的应用前景。采用回流搅拌并水热还原的方法制备氟化石墨烯,并在不加HF的情况下以同样的方式制备了水热还原的还原氧化石墨烯(rGO)。采用傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、拉曼光谱(Raman)、X射线光电子能谱(XPS)、透射电镜(TEM)等对样品进行形貌观测和表征。FTIR的结果表明氟化产物中含有C-F键和部分未完全还原的含氧基团;由XRD谱可以看出,产物晶型较差,其层间距和原料的性质有关;Raman谱证实了石墨烯的基本结构依然存在,但也存在大量缺陷,并且rGO比FGS的规整度略高;XPS谱表明样品表面有氟元素的存在,意味着FGS制备成功;TEM结果显示该样品为单层和少层。该方法操作简单、原料廉价易得、工艺要求不高,适用于批量生产氟化石墨烯。     

自交联水性聚氨酯-含氟丙烯酸酯乳液的制备及研究

以异佛尔酮二异氰酸酯(IPDI)、聚碳酸酯二醇(PCDL)、二羟甲基丁酸(DMBA)、1,4-丁二醇(BDO)、甲基丙烯酸羟乙酯(HEMA)为原料合成了双键封端的聚氨酯预聚体;以N-羟乙基丙烯酰胺(HEAA)作交联剂,配合甲基丙烯酸六氟丁酯(HFBMA)等单体进行乳液共聚,制备了自交联水性聚氨酯-含氟丙烯酸酯(FPUA)乳液。研究了HFBMA和HEAA用量对膜耐水性、热性能以及力学性能的影响。结果表明:PUA乳液的耐水性和疏水性随HFBMA用量的增加而增加;随着HEAA用量增加,胶膜的热稳定性增加,拉伸强度增加,伸长率下降;当胶膜中HFBMA质量分数为12%,且HEAA质量分数为2.6%时,乳液的粒径为128 nm,乳液的稳定性较好;胶膜的水接触角为107.6°,吸水率为4.5%,拉伸强度为25.6 MPa,断裂伸长率为268%,10%热失重温度299.6℃。     

Influence of fluorine-containing side chain on the properties of waterborne polyurethane-urea

In order to prepare waterborne polyurethane with excellent water resistance and thermodynamic properties, a series of side chain fluorinated waterborne polyurethane-urea (FWPU-UA) was synthesized with polytetramethylene ether glycol, N-(2-methyl-1,3-propanediol-2′-)-perfluoro-1-butanesulfonyl amine (NPBA), isophorone diisocyanate, and isophoronediamine. With the increase of NPBA content, the weight loss temperature, glass transition temperature, and tensile strength of FWPU-UA were all improved. Gaussian fitting analysis of infrared data and density functional theory simulation proved that the introduction of fluorine side chains increased the interaction of hydrogen bonding in the FWPU-UA. X-ray photoelectron spectroscopy analysis indicated that the aggregation of fluorine atoms on the surface of film were caused by the migration and enrichment of fluorine side chains. Furthermore, the water resistance of polyurethane-urea film could be significantly improved by adding a small amount of NPBA, and the seven-day water absorption rate of polyurethane-urea film was reduced from 30.13% to 12.55%.     

Atom transfer radical polymerization (ATRP): A versatile and forceful tool for functional membranes

The progress in atom transfer radical polymerization (ATRP) provides an effective means for the design and preparation of functional membranes. Polymeric membranes with different macromolecular architectures applied in fuel cells, including block and graft copolymers are conveniently prepared via ATRP. Moreover, ATRP has also been widely used to introduce functionality onto the membrane surface to enhance its use in specific applications, such as antifouling, stimuli-responsive, adsorption function and pervaporation. In this review, the recent design and synthesis of advanced functional membranes via the ATRP technique are discussed in detail and their especial advantages are highlighted by selected examples extract the principles for preparation or modification of membranes using the ATRP methodology.     

室温自交联水性含氟聚氨酯-聚丙烯酸酯复合乳液的制备

采用原位无皂乳液聚合工艺,以丙烯酸单体为溶剂,双丙酮丙烯酰胺（DAAM)和己二酰肼（ADH)为交联体系得到室温自交联水性含氟聚氨酯-聚丙烯酸酯（WFPUA)。通过红外光谱（FT-IR)、透射电镜（TEM)和原子力显微镜（AFM)对聚合物结构进行了表征。同时,研究了含氟量,酮肼交联比例对WFPUA胶膜的性能影响。结果显示,当含氟量为8%、酮肼摩尔比为1：1时,接触角能达到110.5?,吸水率下降至8.8%,抗拉强度从18.12MPa提高至28.55MPa。热重分析表明,酮肼交联的引入有效提高了乳胶膜的热稳定性。     

十二氟庚基丙基甲基二甲氧基硅烷含量对含氟有机硅/二氧化硅杂化涂层性能的影响

采用溶胶–凝胶法,以正硅酸乙酯(TEOS)为SiO2前驱物,二甲基二乙氧基硅烷(DMDES)和十二氟庚基丙基甲基二甲氧基硅烷(12FHPMDMS)为有机硅前驱物,制备得到含氟有机硅/SiO2溶胶,经热固化后得到了不同12FHPMDMS含量的含氟有机硅/SiO2杂化涂层。通过红外光谱表征了溶胶及固化后涂层的结构,采用热重分析仪(TGA)、接触角仪对涂层性能进行分析并测试了其附着力、硬度、冲击强度和耐盐雾腐蚀性(NSS)。结果表明:含氟有机硅/SiO2杂化涂层具有良好的机械性能;随着12FHPMDMS加入量增加,含氟有机硅/SiO2杂化涂层的耐热性提高,接触角先增大后减小。当n(TEOS)∶n(DMDES)∶n(12FHPMDMS)=10∶8∶4时,疏水性最好,接触角达到110.0°且涂层综合性能最佳。     

含氟丙烯酸酯聚合物乳液的合成及涂膜性能研究

采用核-壳乳液聚合法制备了含氟丙烯酸酯聚合物乳液,讨论了含氟单体——甲基丙烯酸六氟丁酯(HFMA)用量、复合乳化剂体系用量、引发剂用量、N-羟甲基丙烯酰胺(NMA)用量、聚合反应温度、反应时间、搅拌速度对聚合反应最终单体转化率以及乳液聚合稳定性的影响;测试了涂膜的吸水率和乳液的黏度,以考察涂膜的耐水性。通过傅立叶红外光谱(FT-IR)对乳胶膜的组成和结构进行表征,结果表明,含氟单体HFMA通过接枝共聚反应与丙烯酸酯进行了有效的结合。