Synergistic Effects of Polybenzimidazole and Aramide on Enhancing Flame-Retardancy and Solubility

Aromatic and functional polymers with processibility derived from biobased starting materials are prerequisite considering sustainable society. Poly(2,5-benzimidazole)s are rigid-rod polymers to show ultrahigh thermal stability such as flame retardance, while usually suffer from poor solubility. Here, poly(benzimidazole-co-amide)s are synthesized from two biobased monomers, 3,4-diaminobenzoic acid and a semirigid comonomer, 4-aminohydrocinnamic acid. The copolymers with an amide composition of 80 mol% and higher are soluble in widely used polar solvents to fabricate the films keeping high flame retardance, which is comparable with popular high-performance polymers such as aromatic polyimides, polyetheretherketone, polyphenylene sulfide, etc.     

Nucleation‐controlled dual semicrystalline morphology of polyamide 11

Crystallization of polyamide 11 at low supercooling of the melt proceeds via heterogeneous nucleation and spherulitic growth of lamellae, while at temperatures close to the glass transition homogeneous nucleation prevails, preventing spherulite formation and leading to formation of a large number of nanometer‐sized mesophase domains. It is shown that spherulitic and non‐spherulitic crystallization at low and high supercooling of the melt, respectively, can be enforced by tailoring the cooling conditions, causing a twofold semicrystalline morphology at ambient temperature. Analysis of non‐isothermal crystallization as a function of the cooling rate, using fast scanning chip calorimetry, reveals that in the case of polyamide 11 such twofold semicrystalline morphology is predicted when cooling at rates between about 20 and 200 K s^?1, since then two separate crystallization events are observed. The prediction has been confirmed by preparation of films crystallized during ballistic cooling at different rates which then were analyzed regarding their structure using optical microscopy, X‐ray diffraction and calorimetry. The study is completed by discussion of implications of twofold non‐isothermal crystallization for structure evolution in polymer processing, as well as by providing information that such behavior is not only typical for polyamide 11 but also for isotactic polypropylene or poly(butylene terephthalate) as two further examples. © 2018 Society of Chemical Industry     

Comparative performance of carbon nanotube and nanoclay on thermal properties and flammability behavior of amorphous polyamide/SEBS blend

Multiwall carbon nanotubes (CNT) or montmorillonite clay (MMT-30B) were added to a poly(hexamethylene isophthalamide-co-terephthalamine) (an amorphous polyamide - aPA) and styrene-ethylene/butylene-styrene graphitized with maleic anhydride (SEBS) blend, in different concentrations, in order to investigate the morphology, thermal properties and flammability behavior. Different nanoparticle localizations in the phase blend were observed through transmission electronic microscopy. CNT nanoparticles are localized in SEBS phase, and MMT-30B nanoparticles in aPA phase. No significant changes were observed on transition temperatures and thermal stability with both nanoparticle additions. However, a slight increase on storage modulus for clay nanocomposites and a slight reduction for carbon nanotube nanocomposites were observed, due to their different phase localizations. Regarding flammability, CNT nanocomposites showed better performance as a flame retardant when compared to samples with MMT-30B. Although the MMT-30B nanocomposites could not be classified according to the UL-94 criteria, no dripped flaming particles were observed, due to the a char barrier formation on the polymer surface. The CNT nanocomposites were classified according to the UL-94 criteria as V-2. The CNT's selective localization on the SEBS phase decreases its heat-release rate, but no interconnected network structure was formed in the matrix to suppress the dripping flaming particles.     

Sulfonylguanidine Derivatives as Potential Antimelanoma Agents

Sulfonylguanidines are interesting bioactive compounds with a broad range of applications in the treatment of different pathologies. 2-Aminobenzazole-based structures are well employed in the development of new anticancer drugs. Two series of novel N-benzazol-2-yl-N′-sulfonyl guanidine derivatives were synthesized with the sulfonylguanidine in either an extra- or intracyclic frame. They were evaluated for their antiproliferative activity against malignant melanoma tumor cells, thus allowing structure-activity relationships to be defined. Additionally, NCI-60 screening was performed for the best analogue to study its efficiency against a panel of other cancer cell lines. The stability profile of this promising compound was then validated. During the synthetic process, an unexpected new deamidination of the sulfonylguanidine towards sulfonamide function was also identified.     

改性三氧化二锑协效二乙基次磷酸铝阻燃PA6研究

采用硅烷偶联剂（KH560）对三氧化二锑（Sb₂O₃）进行表面改性处理，并将其协效二乙基次磷酸铝（ADP）应用于聚酰胺6（PA6）阻燃研究。采用傅里叶变换红外光谱和热失重分析对改性Sb₂O₃进行表征，运用垂直燃烧、氧指数、锥形量热仪、热分析以及扫描电子显微镜和拉曼光谱等对阻燃PA6进行了阻燃性能及机理分析。结果表明，改性 Sb₂O₃与Sb₂O₃相比，与ADP具有更好的协同阻燃效应，其作用机制主要是在气相发挥阻燃作用；当ADP含量为8 %，改性Sb₂O₃含量为2 %时，阻燃PA6复合材料的UL 94等级达到V?0级，极限氧指数达到33.8 %。     

介孔分子硅剂改善茶浓缩膜结构特性应用研究

为有效提高功能性茶浓缩反渗透膜的回收效率和抗污性能,探究了3种介孔分子硅材料(MCM-41、SBA-15和MCFs)对浓缩膜面聚酰胺层聚合形成过程的结构影响。结果表明,添加质量分数0.02%经磺化预处理的MCM-41于间苯二胺水相可接枝酰氯基团,形成的聚酰胺结构层峰谷粗糙跨度仅为220 nm且交联紧致,膜抗拉伸强度增加37.8%;SBA-15和MCFs相膜面峰谷跨度达500~780 nm,横向褶皱和团聚,结构存在孔道塌陷;改性膜在3 h内对茶多酚、茶多糖、茶蛋白即可达到最大浓缩度,减少50%浓缩时间;MCM-41和SBA-15膜长时间运行的浓缩降率仅为2.8%~6.1%,48 h下降率比显示改性膜达标使用时长增加112.5%~137.5%,亲水性和抗污堵能力均大幅提升,可有效满足功能化茶浓缩精度。     

界面聚合聚酰胺纳滤膜渗透选择性能优化的研究进展

纳滤因其分离效率高、操作压力低、环境友好等优点，在废水处理、海水淡化和工业分离纯化等众多领域有着重要的应用。界面聚合法制备的聚酰胺（PA）纳滤膜是最为常用的纳滤膜种类之一。然而界面聚合反应速度快，如何通过调控界面聚合过程，优化纳滤膜选择分离层的结构从而提高渗透选择性，以满足不同领域对纳滤膜需求仍是亟需解决的问题。本文从影响界面聚合单体扩散因素的角度出发，综述了近年来PA纳滤膜渗透选择性能优化的研究进展，包括新型PA纳滤膜、纳米材料/PA混合基质膜及超薄PA纳滤膜3个方面，探讨了选择分离层结构调控与纳滤膜渗透选择性能优化的关系，最后指出目前界面聚合制备高渗透选择性PA纳滤膜在规模化、稳定性及可控性存在的问题，并对未来界面聚合纳滤膜在微观结构和聚合过程调控方面的研究进行了展望。     

Preparation of silver nanoparticle functionalized polyamide fibers with antimicrobial activity and electrical conductivity

In this work, silver nanoparticle functionalized polyamide 6 (PA6) fibers were prepared using the electroless plating method. The surface of PA6 fibers was modified by exploiting dopamine/CuSO₄/H₂O₂ system prior to electroless plating to enhance the bonding force between the fiber and the silver nanoparticles. It was found that both the formation rate and the chemical stability of polydopamine (PDA) coatings on the PA6 fiber surface were improved by the introduction of CuSO₄/H₂O₂. The results confirmed the successful deposition of silver nanoparticles on PA6 fiber surface and the average particle diameter of 223 nm. Compared with uncoated fibers, the silver plated PA6 fibers exhibited excellent antimicrobial activity to both Escherichia coli and Staphylococcus aureus (with an antimicrobial efficiency of 99.9% and 100%, respectively). The electrical resistance of the silver coated PA6 fibers reached 0.98 Ω over a length of 1 cm, indicating a good electrical conductivity. In particular, coating durability of the formed silver layer was investigated by subjecting the fibers to various mechanical deformations, and the results showed that the formed silver layer was maintained well after 50 times of cyclic stretching at a constant displacement of 10 mm. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47584.