The migration of nanoparticles in polymer matrix is significant for the structure and performance of polymer nanocomposites after the initial formation. However, the understanding and controlling of migration of nano particles in polymer matrix remains a challenge. Herein, we report using ultraviolet (UV) light to perform the directional migration of inorganic nanoparticles in polymer film, generating an ultrathin (100-200 nm) nano particle layer on the light exposure surface of the film. The prepared iron-doped titania nanoparticles (Fe-TiO2) are initially uniformly dispersed into polyvinyl butyral (PVB) film, and homogeneous distribution remains unchanged even after thermal treatment. However, the UV irradiation induces the directional migration of nano particles towards the illuminated surface. The mechanism indicates that the directional migration of nanoparticles is related with the increase of interfacial energy and conformational entropic effect between Fe-TiO2 and PVB upon UV irradiation. The formed nanoparticle layer endowed the PVB/Fe-TiO2 film with superior UV-stability. Our work extends the study of controlling migration of nanoparticles in polymer matrix by applying external stimuli, and provides a novel strategy for the functionalization of polymer nanocomposite materials.

Surfactants are often used as a cooperation stabilizer with solid particles for increasing the efficiency of Pickering emulsion. Accordingly, the effects of interaction between surfactants and solid particles on stabilizing Pickering emulsions have been attracting great attention. In this study, magnesium hydroxide (MH) nanosheets adsorbed with different amounts of sodium dodecyl sulfate (SDS) surfactants were designed and used to stabilize paraffin-water emulsions. Using SDS-adsorbed MH nanosheets as a stabilizer, the phenomenon of double phase inversion was found for Pickering emulsion. Pickering emulsion was inverted initially from O/W to W/O at about 0.022 mmol/g of the adsorption amount of SDS on the MH nanosheets, and subsequently back to O/W at about 2.312 mmol/g. The first phase inversion was because of the increased hydrophobicity of modified MH nanosheets, where SDS molecules were monolayer-adsorbed on the MH nanosheets surface. The second phase inversion occurred due to the bilayer adsorption of SDS on MH nanosheets, which converted the modified MH nanosheets hydrophilic again. These results are of great importance to understanding the double phase inversion of Pickering emulsions with the addition of surfactants and finding prospective applications in fields such as reversible drilling fluids and oil extraction.

Researches about the heterogeneous nucleation ability of nanorods and the weather resistance of polypropylene (PP) foams were very limited. In this study, the well‐defined rutile TiO 2 nanorods with UV‐absorbing function were coated with silica and then calcined. The obtained nanorods (denoted as “TS”) could be uniformly dispersed in PP matrix by melt blending. The foaming behavior of linear PP and its composites was investigated by using supercritical carbon dioxide (scCO 2 ) as a physical foaming agent. The results demonstrated that the addition of 5 wt% TS made PP/TS‐5% foam have higher cell density, regular cell structure and uniform cell distribution owing to the large numbers of nucleation sites provided by well‐dispersed TS nanorods. At the same time, the aging performance of PP foam samples was evaluated by the changes of macro or micro morphology, melting and crystallization behavior before and after UVB irradiation. It was intuitively found that the damage to the surface of PP foams caused by UV light, involving the erosion of surface, the collapse of cells and the degradation of PP chains could be significantly suppressed by the incorporation of TS nanorods. These findings indicated that TS nanorods could be used as multifunctional nanofillers to achieve the PP foams with improved foamability and photostability.

Magnesium hydroxide (MH) nanoparticles have been considered as an excellent nonhalogen flame-retardant. However, the drawbacks of easy aggregation and relatively low flame retardancy limit their applications in polymer materials. In this research, MH nanoparticles were successfully grafted by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) through the bridge of vinyl silane coupling agents (WD70). The grafted MH nanoparticles (MH-WD70-DOPO) were characterized by Fourier transform infrared spectra,P-31 nuclear magnetic resonance spectra, thermogravimetric analysis, transmission electron microscopy, and X-ray photoelectron spectroscopy spectra. MH-WD70-DOPO nanoparticles were incorporated into ethylene-vinyl acetate copolymer (EVA) matrix by melt blending method. The results indicated that MH-WD70-DOPO nanoparticles were much homogenously dispersed in EVA matrix than unmodified MH particles. EVA/MH-WD70-DOPO nanocomposites with 51.32 wt% loading showed higher flame retardancy, better mechanical and processing properties compared with EVA/MH-WD70 sample. These findings could provide a novel method to enhance the flame-retardant efficiency of inorganic hydroxide flame retardants, while keeping good mechanical and processing properties of polymer materials.

A novel microencapsulated ammonium polyphosphate (MAPP) with shell of crosslinked beta-cyclodextrin (HDI-CD) was prepared. The HDI-CD shell had a fibrous structure and covered with good completeness on the APP core, and a solid chemical bonding was found between the APP core and HDI-CD shell. The microcapsules were more hydrophobic than the pristine APP. When compounded within polypropylene (PP), the MAPP exhibited good compatibility and dispersibility. The combustion testing results showed that the novel all-in-one intumescent flame retardant had efficient flame retardancy for PP materials.

The unique properties of organic-inorganic composite microspheres with armor structure have aroused great interest. Armor structure organic-inorganic composite microspheres were prepared by Pickering suspension polymerization using styrene as monomer, azobisisobutyronitrile ( AIBN ) as initiator, magnesium hydroxide nanosheets as Pickering stabilizer. The composite microspheres were characterized by scanning election microscopy ( SEM ) , transmission electron microscopy ( TEM ) , energy dispersive spectroscopy ( EDS ) , Fourier transform infrared spectroscopy ( FTIR) , X-ray diffraction ( XRD) , thermal gravimetric analysis ( TGA ) and micro-scale combustion calorimetry ( MCC) . The morphology and structure of the composite microspheres were confirmed. Magnesium hydroxide was tightly coated on the surface of the polystyrene microspheres to form the armor structure composite microspheres with magnesium hydroxide as the outer layer and polystyrene as the inner sphere. When magnesium hydroxide content was 2% , the average particle size of the microspheres was 25 mu m, much lower than that of pure PS microspheres , 760 mu m. It was also proved that the composite microspheres with armor structure could reduce the heat release rate and inhibit the cracking of polymers. And the acid etching of microspheres could remove completely the outer layer of magnesium hydroxide. This Pickering suspension polymerization is simple to operate, low cost, and the prepared armor composite microspheres have small particle size, narrow distribution and high sphericity. Moreover, the armor structure endows the material with a certain degree of flame retardant performance.

ABSTRACT This work presents the synthesis of crosslinked hexamethylene diisocyanate β‐cyclodextrins (HDI‐CDs) by reacting β‐cyclodextrin (β‐CD) with HDI as a crosslinking agent at different feed ratios. As a novel char‐forming agent, the HDI‐CDs are combined with ammonium polyphosphate (APP) and applied in polypropylene (PP) to form intumescent flame‐retardant composites. The structure of HDI‐CDs is characterized by Fourier transform infrared spectra (FTIR), 13 C nuclear magnetic resonance spectroscopy, and nitrogen adsorption–desorption test. The thermogravimetric analysis (TGA) results indicate that HDI‐CDs have better char‐forming performance than β‐CD. FTIR spectra, X‐ray diffraction, and Raman spectra characterization demonstrate that the reaction between HDI‐CDs and APP contributes to the formation of a more stable char layer than β‐CD and APP. According to the results of TGA, scanning electron microscopy, limiting oxygen index (LOI), UL‐94, and X‐ray photoelectron spectroscopy test, when the crosslinking degree of HDI‐CDs is high enough (not less than β‐CD:HDI = 1:3.6), the PP/APP/HDI‐CDs composites can form a compact and dense char layer during combustion. Among all composites, PP/APP/HDI‐CD(4) shows the best flame‐retardant performance, which can pass the UL 94 V‐0 rating with an LOI value of 32.8% when the loading of flame retardants is 28 wt %. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 48320.

Polypropylene-grafted nanosilica (PP-g-SiO2) was prepared by us as a new modified nanosilica with long polymer chains and high grafting density. It was found that the addition of PP-g-SiO2 resulted in remarkable strain-hardening behavior of PP. Herein, the foaming behavior of isotactic polypropylene (iPP)/PP-g-SiO2 nanocomposites was investigated by using supercritical carbon dioxide (scCO(2)) as a blowing agent. The results demonstrated that the incorporation of PP-g-SiO2 could obviously enhance the foamability of iPP. In particular, the uniform cell distribution and smaller cell size could be obtained by 1 wt% particle loading, and 5 wt% particle content showed a wider foaming temperature range and higher cell density. The noticeable enhancement in the foamability of iPP was attributed to the reinforced melt strength, high melt elasticity and the increased heterogeneous nucleation caused by well dispersed and long polypropylene chains grafted SiO2. These findings provide new insights to improve the foaming ability of iPP with incorporation of modified nanoparticles.

Rutile TiO2 is commonly used as UV shielding agent because of the absorption of UV light. In this research, we integrated the function of ruffle TiO2 nanoparticles and antioxidants (AO), and prepared a kind of multi-functionalTiO(2) nanoparticles with the capacity of both UV absorption and antioxidation. Firstly, ruffle TiO2 nanorods were prepared and encapsulated by SiO2 to decrease its photocatalytic activity. Then, antioxidant functionalized silica-coated TiO2 nanorods (AO-KH550-SiO2-TiO2) were successfully synthesized by using aminosilane coupling agent (KH550) as a bridge. By melt blending method, AO-KH550-SiO2-TiO2 were incorporated into PP matrix. The results indicated that AO-KH550-SiO2-TiO2 could improve both photo stability and thermal stability of PP. PP/AO-KH550-SiO2-TiO2 film broke after 220 h UV irradiation, and the broken time of PP/TiO2 film was only 80 h. And the oxidation induction time of PP/AO-KH550-SiO2-TiO2 sample was 4.7 min, while PP/TiO2 sample showed no antioxidation effect. In addition, AO-KH550-SiO2-TiO2 exhibited excellent anti-extraction property. This novel design of AO-KH550-SiO2-TiO2 may open up a new avenue for fabricating multi-functional nanoparticles and facilitating their practical application.

Titanium dioxide (TiO2) has been widely used as the white pigment in paintings and coatings. It is of significance to endow TiO2 powders with the high conductivity to extend its application. In this research, rutile TiO2 nanorods were prepared as the substrate material. Further the surface coating by antimony doped tin dioxide (Sb-SnO2) shell layers was achieved to obtain conductive TiO2 nanorods. The morphology and structure of TiO2@Sb-SnO2 nanorods was mainly focused on to obtain high conductivity by optimizing the calcination temperature. When the temperature was properly applied at nearly 500 degrees C, the calcination led to the fusion and attachment of Sb-SnO2 crystalline regions on the surface of TiO2 nanorods, forming a continuous intact coating layer and thus getting lower volume electrical resistivity of the composite nanopowder. However, after calcination at 600 degrees C or higher temperature, the integrity of Sb-SnO2 shell layers would be destroyed, resulting in the increased electrical resistivity. The conductive TiO2 nanorods obtained at the optimized reaction condition showed a very low resistivity of 52 +/- 1.6 Omega cm, in contrast to 10(5)Omega cm of the pure TiO2. The conductive TiO2 nanorods would be excellent candidate for antistatic or electromagnetic shielding applications in coatings.

聚合物/二氧化钛纳米杂化材料可综合不同组分材料的优势,实现性能优化,满足实际应用中对材料的需求.本文详细介绍了本课题组近几年来在聚合物/二氧化钛纳米杂化材料的设计与制备方面的研究进展,主要涉及聚合物负载光催化剂和聚合物光稳定与光降解两方面内容.

The growth kinetics of quantum dots (QDs) is of great importance to control and understand their particle size evolution. Water content is an important parameter for the growth of ZnO QDs during the sol-gel process, which has not been precisely studied until now. Herein, a modified sol-gel method was proposed to prepare uniform and mono-dispersed ZnO QDs. In this method, water content was precisely controlled, which facilitated the thorough investigation concerning the effects of water content on growth kinetics of ZnO QDs. When the water content was low (<= 90 mM), the precursor solution was stable and the generation of ZnO QDs could not be triggered. When the water content was too high (3 M), Zn-HDS was generated instead of ZnO. When the water content was in an appropriate range (360 mM-900 mM), the growth of ZnO QDs followed two stages: the oriented attachment (OA) and the Ostwald ripening (OR) stage. Based on our particle size calculation results by Sarma Model, which showed more distinct differentiation and better pertinence than EMA Model, it has been proved that the increase in the water content could not only promote the growth rate of OA stage, but also the OR stage. This results changed our previous thinking that water content has no influence to the OR stage.

Rutile TiO2 are widely used for applications of coatings, cosmetics, photoelectric devices and so on. However, effective control of well-defined morphology, size and composition of rutile TiO2 nanoparticles from agglomeration has always been a challenge. A new synthesis strategy was proposed to prepare rutile TiO2 with controllable morphology varied from flower-like structures to single-separated nanorods. The β-FeOOH nanoparticles were generated by the hydrolysis of FeCl3 solution and could prevent the aggregation of TiO2 nanocrystals at early stages of the reaction; thus, could control the morphology of rutile nanoparticles. The morphology of rutile TiO2 nanoparticles could be controllably regulated from flower-like structures to individually separated nanorods. Meanwhile, the preformed β-FeOOH also played a role of dopant. Fe ions were substitutionally doped into the bulk lattice of TiO2 nanocrystals and reduced the bandgap, which extended the solar radiation absorption range of rutile TiO2. The prepared TiO2 may be suitable for novel UV-blue light shielding agents and many other applications in photoelectric devices, photocatalysis, and so on due to its small size, unprecedented discrete rod-like structure and unique UV-vis light permeability.

Grafting polyolefin chains onto the surface of silica nanoparticles to form satisfactory polyolefin/silica nanocomposites still remains a challenge, even after the complicated functionalization of the polyolefin chains and surface modification of the silica. In this study, an efficient route for the preparation of polypropylene-grafted nanosilica (PP-g-SiO2) masterbatch was presented through the reactive melt blending of maleic-anhydride-grafted polypropylene (PP-MAH) and amino-functionalized silica (SN-NH2) synthesized by the co-condensation method. The amount of grafted PP chains could achieve to 80.8 wt%. And PP-g-SiO2 exhibited fine dispersion in PP matrix. The shear and extension rheology results of PP/PP-g-SiO2 nanocomposites showed that melt strength of PP could be enhanced remarkably by incorporation of PP-g-SiO2 masterbatch, which revealed the strong interactions between PP-g-SiO2 and PP matrix. These findings provide a facile way to prepare polyolefin-grafted nanosilica, while expanding the potential applications of nanosilica in polyolefin nanocomposites. (C) 2018 Elsevier Ltd. All rights reserved.

Antioxidants are used to improve the thermo-oxidative stability of polymers during processing and to prolong the service life of polymer materials. Immobilizing antioxidants onto nanoparticles is one of the approaches for reducing their physical losses. Research on the design, synthesis and application of nanoparticle-immobilized antioxidants is reviewed in this article. These kinds of nano-antioxidants' reveal good resistance against extraction and show good antioxidative efficiency during long-term thermal aging, and therefore will have great potential in practical use for improving the stability of polymer materials. (c) 2018 Society of Chemical Industry

ABSTRACTEncapsulation of expandable graphite (EG) particles by organic or inorganic shells has been proved to efficiently enhance the expandability of EG, and thus to improve the flame‐retardant efficiency of EG. In this study, magnesium hydroxide (MH) nanosheets were utilized to fabricate core–shell EG@MH flame‐retardant particles through a heterocoagulation method. It was observed that after the encapsulation by MH nanosheets, the edges of the char residue of the EG layer were sealed after combustion, which contributed to the enhancement of expandability. The expansion volume of EG@MH increased dramatically to 456 mL/g, in contrast to 338 mL/g for pure EG. By incorporating 11.5 wt % of flame‐retardant particles, polyurethane foam containing EG@MH (here PU‐EG@MH) displayed excellent flame retardancy. Compared with the physically mixed sample, PU‐EG+MH, the limiting oxygen index value for the PU‐EG@MH sample increased from 29.8% to 32.6%. Furthermore, the shell of MH nanosheets was beneficial for improving the interfacial adherence between EG and the rigid polyurethane foam (RPUF) matrix, due to the reaction between isocyanate functional groups and MH. The cell structure and storage modulus of PU‐EG@MH were improved. In other words, the shell of MH nanosheets successfully improved the flame‐retardant efficiency and enhanced the interface adhesion between EG and the matrix. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46749.

Physical loss of stabilizers by migration and extraction accelerates the degradation of polymer materials. In this work, amino-containing nanosilica with anti-aging properties was prepared simply by the co-condensation of tetraethoxysilane and N-(2-aminoethyl)-3-aminoproply-trimethoxysilane (AEAPS). AEAPS was used to introduce amino groups into silica nanoparticles and to act as a catalyst in this process. The co-condensed nanosilica (CCS) showed agglomerate structure similar to the typical fumed nanosilica (FS). The amino groups were distributed both on the surface and inside the nanoparticles. HDPE/CCS and HDPE/FS composites were prepared by melt blending. Thermogravimetric analysis and oxidative induction time showed that CCS has effectively improved the thermo-oxidative stability of HDPE. In the long-term accelerated thermo-oxidative aging and UV aging tests, HDPE/CCS composite showed superior stability to neat HDPE and HDPE/FS composite. The results of infrared spectroscopy and electron paramagnetic resonance suggested that the HDPE/CCS composite manifested a special degradation mechanism involving the nucleophilic addition of amino groups to carbonyl species as well as the oxidation of amino groups on CCS by peroxides. The amino groups on CCS consumed carbonyl species and peroxides, and generated hydroxylamines and nitroxide radicals which were able to eliminate free radicals, thus restrained the degradation of HDPE.

As a new member of carbon dots (CDs), Polymer dots (PDs) prepared by hydrothermal treatment of polymers, usually consist of the carbon core and the connected partially degraded polymer chains. This type of CDs might possess aqueous solubility, non-toxicity, excellent stability against photo-bleaching and high visible light activity. In this research, PDs were prepared by a moderate hydrothermal treatment of polyvinyl alcohol, and PDs grafted TiO2 (PDs-TiO2) nanohybrids with TiOC bonds were prepared by a facile in-situ hydrothermal treatment of PDs and Ti (SO4)2. Under visible light irradiation, the PDs-TiO2 demonstrate excellent photocatalytic activity for methyl orange degradation, and the photocatalytic rate constant of PDs-TiO2 is 3.6 and 9.5 times higher than that of pure TiO2 and commercial P25, respectively. In addition, the PDs-TiO2 exhibit good recycle stability under UV-Vis light irradiation. The interfacial TiOC bonds and the π-conjugated structures in PDs-TiO2 can act as the pathways to quickly transfer the excited electrons between PDs and TiO2, therefore contribute to the excellent photocatalytic activity.

Invisible fault identifying in loess area is a difficult problem in active fault study in northern China. Detailed stratigraphic division of loess area by the naked eye is very difficult due to the insignificant difference of the granularities and the colors, which would affect the identification of the obscured fault and paleo -seismic event. Spectral technique has been used for magnetic susceptibility estimation. Magnetic susceptibility (MS) has been considered to be a measure of the degree of pedogenic activity and excellent proxies for terrestrial climatic fluctuations. In this study,multiple linear regression was used to build MS estimation models based on the spectral features. A model was built and was applied to hyperspectral image. Test of datasets indicates that this model is very successful. The applying of this model to hyperspectral image shows that the intensity distribution of MS could be used for stratigraphic division.