Nanocrystalline cellulose/fluorinated polyacrylate latex via RAFT‐mediated surfactant‐free emulsion polymerization and its application as waterborne textile finishing agent

A simple method for nanocrystalline cellulose (NCC)/fluorinated polyacrylate was developed by RAFT‐mediated surfactant‐free emulsion polymerization, in which the nanocomposites formed a core‐shell spherical morphology. The influence of the content of NCC‐g‐(PAA‐b‐PHFBA) (AA was acrylic acid, HFBA was hexafluorobutyl acrylate) on the properties of latex and film were systematically studied. The monomer conversion, the tensile strength, and water–oil repellency of film increased first and then decreased, the latex particle size decreased first and then decreased, when the content of NCC‐g‐(PAA‐b‐PHFBA) increased from 1 to 6 wt %. Elongation at break and thermal stability distinctly decreased when the content of NCC‐g‐(PAA‐b‐PHFBA) gradually increased. XPS showed that the fluorine‐containing groups well concentrated at the film–air interfaces during the annealing process. SEM analysis revealed that the treated fiber had a rugged surface, and the treated fabric had an excellent water repellency. In addition, this green grafting method in water offered a new perspective for the fabrication of exceptional NCC‐based nanocomposites with NCC as the core and also helped to promote the potential applicability of NCC in a range of multipurpose applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1305–1314     

Explosive synchronization in a mobile network in the presence of a positive feedback mechanism

Synchronization is a process that describes the coherent dynamics of a large ensemble of interacting units.The study of explosive synchronization transition attracts considerable attention.Here,I report the explosive transition within the framework of a mobile network,while each oscillator is controlled by global-order parameters of the system.Using numerical simulation,I find that the explosive synchronization(ES)transition behavior can be controlled by simply adjusting the fraction of controlled oscillators.The influences of some parameters on explosive synchronization are studied.Moreover,due to the presence of the positive feedback mechanism,I prevent the occurrence of the synchronization of continuous-phase transition and make phase transition of the system a first-order phase transition accompanied by a hysteresis loop.     

Synthesis and Structure Determination of SCM-15: A 3D Large Pore Zeolite with Interconnected Straight 12×12×10-Ring Channels

A new germanosilicate zeolite named SCM-15 (Sinopec Composite Material No. 15), the first zeolite containing a 3-dimensional (3D) channel system with interconnected 12-, 12-, and 10-ring channels (pore sizes: 6.1×7.2, 6.1×7.4, and 5.2×5.9 Å), has been synthesized using neutral 4-pyrrolidinopyridine as organic structure-directing agents (OSDAs). Its structure has been determined by combining single-crystal electron diffraction (SCED) and synchrotron powder X-ray diffraction (SPXD) data. The unique open framework structure of SCM-15 is related to that of FOS-5 ( BEC ), ITQ-7 ( ISV ), PKU-16 ( POS ), ITQ-26 ( IWS ), ITQ-21, Beta polymorph B, and SU-78B, since all these framework structures can be constructed from similar chains which are connected through shared 4-ring or double 4-ring (d4r) units. Based on this relation, six topologically reasonable 3D large or extra-large pore hypothetical zeolites are predicted.     

Hydroxy double salts intercalated with Mn(II) complexes as potential contrast agents

A series of Mn(II) aminophosphonate complexes were successfully synthesized and intercalated into the hydroxy double salt [Zn₅(OH)₈]Cl₂·yH₂O. Complex incorporation led to an increase in the interlayer spacing from 7.8 to 10–12 Å. Infrared spectroscopy showed the presence of the characteristic vibration peaks of the Mn(II) complexes in the intercalates' spectra, indicating successful incorporation. The complex-loaded composites had somewhat lower proton relaxivities than the pure complexes. Nevertheless, these intercalates may have use as MRI contrast agents for patients with poor kidney function, where traditional Gd(III)-based contrast agents cause severe renal failure.     

Full physicochemical characterization of malic acid: Emphasis in the potential as food ingredient and application in pectin gels

Malic acid, a carboxylic acid most found in fruits, is a smooth taste substance used as flavoring and preservative agent in foods, although not as used as citric acid. There are no studies focusing in quantitative results or investigations on its physicochemical properties, useful to the food industry, or even the confirmation of its calcium chelating, buffer texturizer and antioxidant alleged properties. Thus, the aim of this work was the assessment of most physicochemical properties of malic acid, solid and in solution, that could be useful to the food industry understand its real potential. The following analyses were carried out: melting point; structure (NMR, XRD, FTIR and SEM/EDS); TGA/DTG; solubility, hygroscopicity; antioxidant activity, iron chelating and antibacterial activities and stability of pectin gels. The melting temperature found was 129.71 °C. TGA/DTG exhibited first loss of mass around 140 °C. In the temperature range of 10 to 55 °C, it exhibited a high solubility in water, from 48.12 to 61.49 (100w), respectively. The tested bacteria, related to food spoilage, were inhibited by DL-malic acid 10% or higher. Chelating and antioxidant activities showed expressive results even in 1% solution. Pectin gels with malic acid had stronger structure and less syneresis than citric acid gels. In addition, calcium chelating, buffer texturizer and antioxidant properties were confirmed. Thus, malic acid has potential to be applied in a wide variety of food products as fortified beverages, frozen and refrigerated items, oils, pectin gels, hard and soft candies, and biofilms, due to all the characteristics quantified.     

Radical polymerization in the presence of peroxide and reducing agent monomer for branched polymers

In this article, we report the radical polymerization in the presence of peroxide and commercially available or designed reducing agent monomer (RAM) for the preparation of branched poly(methyl methacrylate)s (PMMAs). The reaction behavior of the RAM was studied by NMR. Triple‐detection SEC (TD‐SEC) analysis was used to confirm the branching structure of the prepared PMMAs and to investigate the influence of peroxide concentration and RAM concentration on molecular weight and branched structure. The obtained branched PMMAs exhibited high molecular weights and relatively narrow polydispersities at high conversion of MMA. Interestingly, a significant increase in molecular weight and degree of branching of the obtained polymers are observed in higher BPO concentration, these results are quite different from that reported in the literature. The unique radical polymerization mechanism in the RAM/BPO redox‐initiated radical polymerization system resulted in branched PMMAs with high molecular weights at relatively high RAM and BPO concentrations. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 833–840     

Curing behavior and properties of high biosourced epoxy resin blends based on a triepoxy monomer and a tricarboxylic acid hardener from 10-undecenoic acid

Renewable propane-1,2,3-triyl tris(9-(oxiran-2-yl) nonanoate) (EGU, 100 wt% biogenic) and a tricarboxylic acid triglyceride (CGTU) hardener (85.7 wt% biogenic) were synthesized from 10-undecenoic acid (10-UDA) and used to produce epoxy resins with 52–92 wt% biobased carbon. CGTU was prepared by thermally activated thiol-ene coupling of thioglycolic acid onto propane-1,2,3-triyl tris(undec-10-enoate), (GUD) in the absence of solvent. The characterized CGTU was used as a green hardener of blends based on EGU and a conventional bisphenol A-based epoxy pre-polymer (DGEBA) at various mass percentages (0–100 wt%) with an stoichiometric epoxy/acid equivalent ratio. Calorimetric studies revealed higher peak temperature, lower reaction heats, and longer gelation times in resins with high EGU proportion, evidencing the lower reactivity of aliphatic EGU compared with aromatic DGEBA. Cured resins were yellowish transparent rubber-like materials with glass transition temperatures (Tg) varying from −14 °C to −42 °C and tensile strength in the range of 1750 kPa–790 kPa, for 0 and 100 wt % EGU, respectively. The soluble fraction of all resins was less than 4.3%, reflecting a high level of crosslinking. Thermosets with high biobased content showed both UV-light protection and visible light transparency.     

Obtaining of a PET-CaF2 hybrid multifilament: Non-isothermal crystallization studies

Poly(ethylene terephthalate) (PET) has been mixed with fluorite (CaF₂) particles to obtain micro- and nano-composites aiming to obtain a hybrid multifilament. In first term, the use of two montanic waxes and an amide wax as dispersing agents towards the compatibilization of the inorganic and organic components of the CaF₂/PET composite were considered. To do this, non-isothermal crystallization studies by differential scanning calorimetry have been carried out. Moreover, the influence of the CaF₂ particle size and concentration on the thermal properties of the system have been also studied by this technique. Finally, the extrapolation of the results has materialised as a novel PET/CaF₂ hybrid multifilament. Thermal and mechanical properties and molecular weight of the multifilament have been as well evaluated.     

Design and build an elastic crosslinked network to strengthen and toughen soybean-meal based bioadhesive using organo-sepiolite and greener crosslinker triglycidylamine

Poor water resistance and curing layer brittleness are significant challenges of greener soybean meal (SM) adhesive promotion and application. In this study an elastic network was built to crosslink the SM adhesive and improve the cured layer toughness of the resultant adhesive. Long-chain organo-sepiolite (OSEP) was first prepared by compound modification using KH-560 and KH-602 silane coupling agents. Triglycidylamine (TGA), a greener crosslinking agent with a large number of effective epoxy functional groups, was then synthesized. SM-based adhesives were fabricated using SM, OSEP and TGA. Results indicated that an elastic network was fabricated by the cross-linked reaction of SM, OSEP, and TGA. The elastic network effectively improved the toughness of the resultant adhesive. The wet shear strength of the plywood (PlyW) bonded by SM with 1% OSEP (SM/TGA/OSEP-1 adhesive) increased by 60% to 1.25 MPa relative to that of the SM/TGA adhesive. This study provided a greener, simple and cheap method improving the toughness and wet shear strength of SM-based adhesive, which contributes to the industrialized application of the product.     

介孔碳材料抑制锂电池负极枝晶生长

为了解决锂电池负极表面锂枝晶生长带来的性能衰退和安全问题。 以沸石咪唑酯骨架-8(ZIF-8)为前驱体制得介孔碳材料(MCM),用于金属锂负极表面改性。 X射线粉末衍射(XRD)和拉曼光谱表明,退火制得的MCM具有一定的石墨化程度,N₂气吸脱附测试(BET)证明MCM具有典型的介孔特征。 对比不同温度退火样品的XRD、拉曼光谱和BET测试结果,确定900 ℃为最佳退火温度。 优化的MCM作为表面改性剂对金属锂负极进行改性研究。 电池充放电循环后,负极样品的XRD和扫描电子显微镜(SEM)测试表明,MCM能够通过均衡锂负极表面的电荷分布抑制金属锂的取向沉积和锂枝晶的生长。 本研究为制备抑制锂电池负极枝晶生长表面改性剂提供了一种简便而有效的合成方法,有利于锂电池循环寿命的延长和安全性能的提高。