In situ preparation of cyclohexanone formaldehyde resin/layered silicate nanocomposites

In this study, in situ modified cyclohexanone formaldehyde resin (CFR) was prepared from clay (montmorillonite) and polydimethylsiloxane with diamine chain ends [α,ω‐diamine poly(dimethyl siloxane) (DA.PDMS)] in the presence of a base catalyst. Different clay contents (from 0.5 to 3 wt %) were used to produce clay‐modified nanocomposite ketonic resins [layered clay (LC)–CFR] and clay‐ and DA.PDMS‐modified nanocomposite ketonic resins (DA.PDMS–LC–CFR). The polymeric nanocomposite material prepared by this method was directly synthesized in one step. These nanocomposites were confirmed from X‐ray diffraction to have a layered structure with a folded or penetrated CFR, and they were further characterized via Fourier transform infrared spectroscopy–attenuated total reflectance and NMR spectroscopy. The thermal properties of all of the resins were studied with differential scanning calorimetry and thermogravimetric analysis. All of the resins showed higher thermal stability than their precursor CFR resin. The obtained samples were also characterized morphologically by scanning electron microscopy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39918.     

In situ preparation and property investigation of polypropylene/fumed silica nanocomposites

We present the preparation of polypropylene (PP)/fumed silica (FS) nanocomposites via in situ polymerization in this article. The approach includes preparation and utilization of a bisupported Ziegler–Natta catalytic system in which magnesium ethoxide and FS are used as conjugate supports of the catalyst. Catalyst preparation and polymerization processes are carried out in the slurry phase and under argon atmosphere. Scanning electron microscopy images show a good dispersion of the FS throughout the PP matrix. Results from differential scanning calorimetry reveal that the crystallization temperature of prepared nanocomposites increases by increasing FS loading. Also, crystal content of nanocomposites increases as the FS concentration increases up to 3.48 wt%. Nanocomposites containing <3.14 wt% of nanoparticles do not show considerable change in their melting point where with more increment in filler concentration, melting temperature slightly increases. Thermogravimetric analysis shows a considerable improvement in the thermal stability of PP/FS nanocomposites compared to pure PP. Rheological studies indicate that the incorporation of FS into PP matrix results in increment in storage modulus, loss modulus, and complex viscosity of polymeric matrix, particularly in low frequency region. By increasing FS loading, the PP/FS nanocomposites show a transition from liquid‐like to solid‐like viscoelasticity behavior depicting microstructural changes in their structures. POLYM. COMPOS., 35:37–44, 2014. © 2013 Society of Plastics Engineers     

In Situ preparation of resol/clay nanocomposites

In this study, in situ modified phenol formaldehyde resins were prepared from hydroxyl terminated polydimethyl siloxane (DH.PDMS), clay (montmorillonite) in the presence of base catalyst. Different clay contents (0.5, 1, 3, 5 wt %) were used to produce DH.PDMS modified resol/clay nanocomposite resins (DH.PDMS‐LC‐PFRs). DH.PDMS‐LC‐PFRs were partially cured by heat, and the effects of the curing process and the clay content in the resol resin were determined on the spectroscopic, thermal, mechanical and microscopic properties of the final products. Furthermore, the effects of the reaction time on the polymerization and on the morphology of the materials were investigated. The structures of the specimens were characterized by means of Fourier Transform Infrared (FTIR‐ATR) spectroscopy. Thermal properties of the samples were determined with Differential Scanning Calorimeter (DSC) and Thermogravimetric Analyzer (TGA). Mechanical properties of the specimens were determined by Dynamic Mechanical Analyzer (DMA). The obtained samples were also characterized morphologically by Scanning Electron Microscope (SEM). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

One-pot in situ ball milling preparation of polymer/graphene nanocomposites

A one-pot method which involves peeling graphite nanosheets (GNs) off into graphenes in polymer solution and in situ forming polymer/graphene sheets nanocomposites by using ball milling is presented. Via this approach, nanocomposites based on maleic anhydride grafted poly (ethylene-co-vinyl acetate) (EVA-g-MAH) and graphene sheets comprising one to five layers were accomplished. The resulted EVA-g-MAH/graphene nanocomposites displayed a percolation threshold around 5.0 wt %, much lower than that of the EVA-g-MAH/GNs nanocomposites prepared by direct solution blending (∼ 13.0 wt %). The nanocomposite containing 10 wt % of graphene sheets exhibited a higher maximum decomposition temperature by ∼ 10°C when compared with the virgin polymer and the corresponding nanocomposite loaded with 10 wt % of GNs. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

In situ processing of electrically conducting graphene/SiC nanocomposites

The outstanding electronic and physico-chemical properties of graphene make it an ideal filler in the fabrication of conducting and robust ceramic composites. In this study, a novel single-step approach for processing electrically conducting and well dispersed graphene/SiC nanocomposites is shown. These materials were processed by growing epitaxial graphene with either α- or β-phase SiC ceramics during their densification via spark plasma sintering (SPS). About 4 vol.% of few-layer graphene domains were generated in situ during the SPS process, leading to a conducting graphene network that significantly enhanced the electrical performance of SiC. The in situ graphene SPS growth mechanism arose from the combined action of the electric current, high temperature and partial vacuum. This approach offers unprecedented opportunities for the fast manufacturing of graphene/SiC nanocomposites with superior electrical and mechanical properties, precluding the handling of potentially hazardous nanostructures. This method widens their possible applications, including micro-electromechanical systems, brakes, micro-turbines or micro-rotors.     

In situ synthesis and properties of PMR PI/SiO2 nanocomposites

Phenylethynyl-terminated polymerization of monomer reactant thermosetting polyimide (PI) was synthesized, and the PI/SiO₂ nanocomposite films were prepared via in situ polymerization of monomer with the nano-SiO₂ particles. Analysis indicated that the surfaces of the nano-SiO₂ slightly react to the PI, and nano-SiO₂ was homogeneously dispersed in the PI at low filling content while agglomerate was a presence of high filling content. Thermogravimetric analysis showed that the decomposition temperatures of the PI/SiO₂ nanocomposites were increasing as the increasing of filler contents when the nano-SiO₂ content was below 9 wt %, but it showed a decreased tendency when it was above 9 wt %. Tribological studies showed that the nano-SiO₂ contributed to the significant decreasing of the friction coefficient and wear rates of the PI at dry sliding condition of low filler content, and the PI/SiO₂ nanocomposites could be promising material used as tribomaterial in dry sliding condition against GCr15 steel. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

In situ fabrication of CuO/UHMWPE nanocomposites and their tribological performance

Polymer nanocomposites present remarkably enhanced mechanical and tribological properties with respect to their matrices even at a low loading of nanofillers. Here, cupric oxide (CuO) nanoparticles (nano-CuO) were in situ filled into ultra-high-molecular-weight polyethylene (UHMWPE) to inhibit a possible agglomeration encountered in the preparation by mechanical mixing. The filled CuO nanoparticles were highly dispersed in UHMWPE with a reliable interface combination. The CuO nanoparticles in the matrix play a role for heterogeneous nucleation, resulting in an enhancement in degree of crystallinity of UHMWPE. The elastic modulus and the elongation at break of the nanocomposites also presented an improvement, indicating a good compatibility between the nano-CuO and the matrix. The average sliding friction coefficient of UHMWPE against 45^# steel was reduced by up to 34% after the in situ filling of CuO nanoparticles, and the wear mechanism was found to transform from adhesive to fatigue wear after the introduction of nano-CuO. It is concluded that the in situ filling can improve the dispersion of CuO nanoparticles in UHMWPE, and markedly promote the mechanical properties and tribological performance of UHMWPE. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47925.     

Microwave‐assisted preparation of polylactide/organomontmorillonite nanocomposites via in situ polymerization

Microwave technology was introduced to assist the synthesis of polylactide (PLA)/organomontmorillonite (OMMT) nanocomposites in bulk by the in situ ring‐opening polymerization of D,L ‐lactide. Factors that influenced the polymerizing effects, such as the microwave power, irradiation time, and dosages of the catalyst and OMMT, were studied in terms of tensile strength. The polymerization time was decreased dramatically to 10 min under 90 W of microwave irradiation, and the mechanical and thermal properties of the PLA/OMMT nanocomposites were significantly improved. The composite with the highest mechanical properties was obtained when the dosages of the OMMT and the catalyst were 1.0 and 0.6 wt % of the lactide, respectively. The initial decomposition temperature of the PLA/OMMT(1.0 wt % OMMT) nanocomposite was heightened 11.5°C compared with that of pure PLA. The results of scanning electron microscopy confirmed an improvement in the toughness with the addition of OMMT. The transmission electron microscopy and X‐ray diffraction results indicate that an exfoliated and intercalated nanocomposite was successfully prepared. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Facile in-situ preparation of polyaniline/graphene nanocomposites using methanesulfonic acid

Polyaniline (PANI)/graphene composites were prepared by the in-situ polymerization of aniline in a 1 M aqueous solution of methanesulfonic acid (MSA) containing graphene, which was prepared separately from graphite powders by simple sonication in MSA. Graphite powders spontaneously exfoliated to form graphene (GPM), which was then quenched with excess water, filtered, and dried to produce powders. The dried graphene powders produced were re-dispersed well in a 1 M MSA aqueous solution, in which the in-situ polymerization of aniline was performed. The resulting PANI/GPM composite had a conducting emeraldine salt (ES) form, and showed good electrical and thermal properties, compared to pure PANI prepared using a 1 M HCl solution. The PANI/GPM composite could be dissolved in a MSA solution and spin-coated in a conducting ES form of PANI. In contrast, the ES form produced from a HCl solution was insoluble in organic solvents and needed to be reduced to convert it to the emeraldine base form to produce a PANI solution. Therefore, the in-situ preparation of PANI/graphene composites using MSA provides a facile means of improving the thermal and electrical properties of PANI and its processability.     

In situ synthesis of bone‐like hydroxyapatite/polyamide 6 nanocomposites

BACKGROUND: Polymer/hydroxyapatite (HA) nanocomposites have emerged in recent years as a new class of biomaterials that can be used as artificial bone. Compared to pure HA or HA‐based bioceramics, and metallic implants, they exhibit good plasticity, improved toughness and good mechanical compatibility with natural bone. Compared to their microcomposite counterparts and the pristine polymer matrix, they show increased tensile strength and modulus, and enhanced bioactivity. RESULTS: In this study, polyamide 6 (PA6)/nanoscale HA (n‐HA) nanocomposites were prepared via in situ hydrolytic ring‐opening polymerization of ε‐caprolactam in the presence of newly synthesized n‐HA aqueous slurry. The synthesized n‐HA, which is similar to bone apatite in chemical composition, microscopic morphology and phase composition, dispersed uniformly in the composites even if its loading was up to 60 wt%. The PA6/n‐HA composites show a similarity to natural bone in chemical composition to a certain extent. Mechanical tests show that the composites are reinforced considerably by the incorporation of needle‐like n‐HA, and the composites have mechanical properties near to those of natural bone. CONCLUSION: The PA6/n‐HA nanocomposite with high n‐HA content shows a similarity to natural bone in terms of chemistry and mechanical properties. This makes it a possible candidate for biomaterials suitable for bone repair or fixation. Copyright © 2008 Society of Chemical Industry     

In situ solvothermal synthesis and characterization of transparent epoxy/TiO2 nanocomposites

A solvothermal process was developed to in situ prepare epoxy (EP)/TiO₂ hybrid precursors. The chemical structure of samples was confirmed by X-ray and Fourier transformed infrared spectroscopy. Field emission scanning electron microscope micrographs of cured EP/TiO₂ hybrid composites showed that well-dispersed TiO₂ nanoparticles were successfully in situ formed in epoxy matrix through the solvothermal process. The thermogravimetic analysis, DSC, and gel content measurements showed that EP/TiO₂ hybrid precursors were fully cured with the glass transition temperature decreasing gradually. The effect of TiO₂ contents on optical and surface properties was investigated in detail. The results indicated that epoxy/TiO₂ nanocomposites exhibited excellent UV shielding effect and high visible light transparency. The contact angle of EP/TiO₂ nanocomposites, when the content of silane-coupling agent (KH560) was 5 g and the content of tetrabutyl titanate (TBT) was 3 g, can reach as high as 101°, which was 36° higher than that of pure EP, representing for the increase of hydrophobicity. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

CdS／PAA纳米复合材料的合成及光学性质研究

以氯化镉、硫化钠、偶氮二异丁氰（AIBN）和丙烯酸（AA）等为原料,原位一步法合成CdS／PAA纳米复合材料。产物通过红外光谱（IR）、紫外-可见吸收光谱（UV—Vis）、荧光光谱（PL）、扫描电子显微镜（SEM）及X-射线衍射花样（XRD）进行表征。根据实验结果给出可能的机理：金属离子首先与聚合物的羧基络合,生成硫化物纳米微粒后,聚合物又包覆在纳米微粒的表面形成保护层。     

In situ growth of well-dispersed CdS nanocrystals in semiconducting polymers

A straight synthetic route to fabricate hybrid nanocomposite films of well-dispersed CdS nanocrystals (NCs) in poly[2-methoxy-5-(2''-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) is reported. A soluble cadmium complex [Cd(SBz)₂]₂·MI, obtained by incorporating a Lewis base (1-methylimidazole, MI) on the cadmium bis(benzyl)thiol, is used as starting reagent in an in situ thermolytic process. CdS NCs with spherical shape nucleate and grow well below 200°C in a relatively short time (30 min). Photoluminescence spectroscopy measurements performed on CdS/MEH-PPV nanocomposites show that CdS photoluminescence peaks are totally quenched inside MEH-PPV, if compared to CdS/PMMA nanocomposites, as expected due to overlapping of the polymer absorption and CdS emission spectra. The CdS NCs are well-dispersed in size and homogeneously distributed within MEH-PPV matrix as proved by transmission electron microscopy. Nanocomposites with different precursor/polymer weight ratios were prepared in the range from 1:4 to 4:1. Highly dense materials, without NCs clustering, were obtained for a weight/weight ratio of 2:3 between precursor and polymer, making these nanocomposites particularly suitable for optoelectronic and solar energy conversion applications.     

In situ fabrication of polyaniline‐silver nanocomposites using soft template of sodium alginate

Polyaniline (PANI)‐Ag nanocomposites were synthesized by in situ chemical polymerization approach using ammonium persulfate and silver nitrate as oxidant. Characterizations of nanocomposites were done by ultraviolet–visible ( UV–vis), Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM). UV–vis, XRD and FTIR analysis established the formation of PANI/Ag nanocomposites and face‐centered‐cubic phase of silver. PANInanofibers were of average diameter ～ 30 nm and several micrometers in length. Morphological analysis showed that the spherical‐shaped silver nanoparticles decorate the surface of PANI nanofibers. Silver nanoparticles of average diameter ～ 5–10 nm were observed on the TEM images for the PANI‐Ag nanocomposites. Such type of PANI‐Ag nanocomposites can be used as bistable switches as well as memory devices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

In situ dynamic vulcanization process in preparation of electrically conductive PP/EPDM thermoplastic vulcanizate/expanded graphite nanocomposites: Effects of state of cure

In situ melt dynamic vulcanization process has been employed to prepare electrically conductive polypropylene (PP)/ethylene–propylene–diene rubber (EPDM) (40/60 wt %) thermoplastic vulcanizates (TPVs) incorporated by expanded graphite (EG) as a conductive filler. Maleic anhydride grafted PP (PP‐g‐MAH) was used as compatibilizer and a sulfur curing system was designed and incorporated to vulcanize the EPDM phase during mixing process. Developed microstructures were characterized using scanning electron microscopy (SEM), melt rheomechanical spectroscopy (RMS), X‐ray diffraction (XRD), and transmission electron microscopy (TEM) and were correlated with electrical conductivity behavior. For comparison, another class of TPV/EG nanocomposites was fabricated using a commercially available PP/EPDM‐based TPV via both direct and masterbatch melt mixing process. Conductivity of the nanocomposites prepared by in situ showed no significant change during dynamic vulcanization till the mixing torque reached to the stationary level where micro‐morphology of the cured rubber droplets was fully developed, and conductivity abrupt was observed. In situ cured nanocomposites showed higher insulator to conductor transition threshold (3.15 vol % EG) than those based on commercially available TPV. All electrically conductive in situ prepared TPV nanocomposites exhibited reinforced melt elasticity with pseudosolid‐like behavior within low frequency region in dynamic melt rheometry indicating formation of physical networks by both EG nanolayers and crosslinked EPDM droplets. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

In situ synthesis of polyamide 6/MWNTs nanocomposites by anionic ring opening polymerization

In situ anionic ring opening polymerization is used to prepare monomer casting polyamide 6 (MCPA6)/carbon nanotubes (CNTs) nanocomposites, whereby water is used as auxiliary dispersing agent of hydroxyl functionalized multiwalled carbon nanotubes (MWNTs‐OH) and ε‐caprolactam (CL) monomer. The MWNTs‐OH were dispersed homogenously in MCPA6 matrix when being observed through transmission electron microcopy. The well dispersed MWNTs‐OH existed at the center of many radial texture phases in MCPA6 matrix. Polarizing microscope analysis showed that these radial texture phases were MCPA6 spherulitic crystallities. Differential scanning calorimetry analysis revealed that the crystallization temperature of the MCPA6/MWNTs‐OH nanocomposites had been improved by adding only 0.2 wt % MWNTs‐OH when compared with pure MCPA6. The influence of MWNTs‐OH on the thermal stability of MCPA6 under nitrogen and air environments was also investigated by thermal gravimetric analysis (TGA). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

In situ polymerization of bio‐based thermosetting polyurethane/graphene oxide nanocomposites

Novel bio‐based polyurethane/graphene oxide (GO) nanocomposites have been successfully synthesized from biorenewable epoxidized soybean‐castor oil fatty acid‐based polyols with considerable improvement in mechanical and thermal properties. The GO was synthesized via a modified pressurized oxidation method, and was investigated using Raman spectra, AFM and XPS, respectively. The toughening mechanism of GO in the bio‐based polyurethane matrix was explored. The elongation at break and toughness of polyurethane were increased by 1.3 and 0.8 times with incorporation of 0.4 wt % GO, respectively. However, insignificant changes in both mechanical strength and modulus were observed by adding GO. The results from thermal analysis indicated that the GO acts as new secondary soft segments in the polyurethane which lead to a considerable decrease in the glass transition temperature and crosslink density. The SEM morphology of the fracture surface after tensile testing showed a considerable aggregation of graphene oxide at concentrations above 0.4 wt %. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41751.