Poly(methyl methacrylate)/clay nanocomposites by photoinitiated free radical polymerization using intercalated monomer

A series of poly(methyl methacrylate)/montmorillonite (PMMA/MMT) nanocomposite were prepared by successfully dispersing the inorganic nanolayers of MMT clay in an organic PMMA matrix via in situ photoinitiated free radical polymerization. Methyl methacrylate monomer was first intercalated into the interlayer regions of organophilic clay hosts by “click” chemistry followed by a typical photoinitiated free radical polymerization. The intercalated monomer was characterized by FT-IR spectroscopy, elemental analysis and thermogravimetric analysis methods. The intercalation ability of the modified monomer and exfoliated nanocomposite structure were confirmed by X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Thermal stability of PMMA/MMT nanocomposites was also studied by both differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).     

Effect of both silane‐grafted and ion‐exchanged organophilic clay in structural,thermal, and mechanical properties of unsaturated polyester nanocomposites

Unsaturated polyester (UPE) resin including styrene monomer was mixed with organophilic montmorillonite (MMT) clay and its crosslinking polymerization reaction was done in the presence of free‐radical initiator. MMT clay was modified with cetyl trimethly ammonium bromide and trimethoxy vinyl silane. The nanocomposites were characterized by X‐ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), thermogravimetric and dynamic mechanical analyses (TGA and DMA). The exfoliated nanocomposite structure was obtained when the MMT clay was modified in the presence of both modifiers, whereas individual modifications all resulted in intercalated structures. The exfoliated UPE nanocomposite exhibited better thermal and dynamic mechanical properties when compared with pure UPE and other composites, even with 3 wt% clay loading. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Preparation and properties of PET/PA6 copolymer/montmorillonite hybrid nanocomposite

From in situ polycondensation, a poly(ethylene terephthalate)/Polyamide 6 copolymer/montmorillonite nanocomposite was prepared, after the treatment of montmorillonite (MMT) with a water soluble polymer. The resulting nanocomposites were characterized by X‐ray diffraction (XRD), differential scanning calorimeter (DSC), nuclear magnetic resonance (NMR), dynamic mechanical analysis (DMA), and transmission electron microscopy (TEM). The results of DSC, ¹H NMR, and DMA proved that the nanocomposite synthesized was PET/PA6 copolymer/MMT nanocomposite, not the PET/PA6 blend/MMT nanocomposite. The results of XRD and TEM proved that the dispersion of MMT was improved observably after the introduction of PA6 molecular chain into PET. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2512–2517, 2006     

Microwave-assisted preparation of poly(2-EHA-co-ST) copolymer and poly(2-EHA-co-ST)/MMT nanocomposite

Copolymerization of 2-ethylhexylacrylate and styrene was performed in presence of benzoyl peroxide as initiator at varying concentrations of the comonomers in a microwave oven. Montmorillonite (MMT) clay was added with a view to prepare nanocomposites, which actually enhanced the water absorption capacity and pressure sensitive adhesive properties. The copolymer and its nanocomposite were characterized by Fourier Transform Infrared, ¹H- and ¹³C-NMR, thermogravimetric-differential thermal analysis (TG-DTA), differential scanning calorimeter, scanning electron microscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The MMT layers were partially exfoliated/intercalated during the polymerization process as evident from the XRD and TEM observations. Their adhesive properties, water absorbancy, and biodegradability in different conditions were studied for their future applications. The monomer reactivity ratios were determined using Finemann–Ross and Kelen–Tüdos method. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

New Role of Layered Silicates as Phase Transfer Catalyst for In Situ Polymerization of Poly(ethylenetetrasulfide) Nanocomposite

In this study, polyethylenetetrasulfide/montmorillonite nanocomposite (PETS/nanoclay) is synthesized from ethylene dichloride and sodium tetrasulfide monomers by in situ polymerization method. The effect of phase-transfer catalyst (PTC) on polymerization kinetics in addition to the structure of resulting PETS containing nanoclay is investigated. The results show that surface-modified montmorillonites by methyl tallow bis-2-hydroxyethyl quaternary ammonium chloride could properly act as PTC. Therefore, it is demonstrated that the addition of nanoclay as PTC reduces the reaction time and increases the polymerization rate during the production of final nanocomposite. The samples were characterized using Fourier transform infrared and Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), nuclear magnetic resonance spectroscopy besides energy-dispersive X-ray spectroscopy (EDS) combined with SEM (SEM–EDX). In addition, thermal behavior of nanocomposite was perused by differential scanning calorimetry and thermogravimetric analysis. XRD and AFM results show proper dispersion of clay in PETS matrix and SEM–EDX results demonstrate suitable distribution of clay in polymer matrix. PETS/nanoclay nanocomposite show a better thermal stability, and also higher glass transition and melt temperature compared to pure polysulfide polymer. The solubility of nanocomposite is also studied and results show that the solubility depends on solvent concentration in addition to reinforcement (nanoclay) deals.     

Synthesis and characterization of montmorillonite/polypyrrole nanocomposite

A novel montmorillonite (MMT)/polypyrrole (PPy) nanocomposite (MPN) with high electrical conductivity and thermal stability has been synthesized via in‐situ polymerization. The surface morphology, characterization, thermal stability, and electrical conductivity have been tested by scanning electron microscopy (SEM), Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and four‐probe methods, respectively. SEM results show that the antenna‐like PPy deposits on the layer surface of MMT. FTIR and XRD analyses show that there is interaction between MMT and PPy. The nanocomposite has high electrical conductivity (4 S/cm), eight orders of magnitude higher than that of pristine MMT. The thermal stability of MPN is higher than the pure PPy as well as the mixture of MMT and PPy (MMP). POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Synthesis of effective poly(4‐vinylpyridine) nanocomposites: in situ polymerization from edges/surfaces and interlayer galleries of clay

Poly(4‐vinylpyridine) (P4VP) nanocomposites have been prepared by using an in situ polymerization method in the presence of organically modified montmorillonite (MMT) clays with a quarternary salt of cocoamine containing a vinyl group, as well as trimethoxy vinyl silane. The nanocomposites were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The desired exfoliated nanocomposite structure was achieved when the MMT modification was conducted in the presence of both modifiers, whereas individual modifications all resulted in intercalated structures. This resultant exfoliated nanocomposite was found to have better thermal stability and dynamic mechanical performance when compared to the other nanocomposites, even with 2 % clay loading. Copyright © 2005 Society of Chemical Industry     

Characterization of PVAc/TiO2 hybrid nanofibers: From fibrous morphologies to molecular structures

Polyvinyl acetate (PVAc)/titanium dioxide (TiO₂) hybrid nanofibers were fabricated by combining sol–gel process with electrospinning technology, which consisted of PVAc as organic segment and TiO₂ as inorganic part. The surface structures of the PVAc/TiO₂ hybrid nanofibrous mats were examined using scanning electron microscopy (SEM). The surface morphology and bulk structures of single nanofiber were investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FTIR) was employed to analyze the chemical structures of the PVAc/TiO₂ hybrid nanofibers. SEM scanning revealed that the fibrous structure was formed. AFM observations presented a significant difference in the morphology of the nanofibers before and after hybridization. It was observed from TEM images that some black streaks with various lengths distributed in a nanofiber. The FTIR analysis indicated the newly formed associated hydrogen bond because of the hybrid effect between PVAc and TiO₂ sol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

原位插层聚合制备PVC/蒙脱土纳米复合材料

采用氯乙烯单体直接插层到蒙脱土中进行原位插层聚合，制备纳米复合材料，并用小角X射线衍射（XRD）、扫描电子显微镜（SEM）和电子探针技术对复合材料进行了结构表征。实验结果表明：采用原位插层聚合法制得的PVC／蒙脱土（MMT）复合材料为剥离型纳米复合材料。     

Preparation and characterization of exfoliated poly(vinyl acetate-co-methyl methacrylate)/Cloisite 30B nanocomposite

Poly(vinyl acetate-co-methyl methacrylate)/Cloisite 30B, P(VAc-co-MMA)/C30B nanocomposite have been prepared via emulsion polymerization method. In the nanocomposite latex preparation sodium lauryl sulfate, ammonium persulfate, and poly(vinyl alcohol) were as anionic emulsifier, conventional anionic initiator, and stabilizer, respectively. The resulting P(VAc-co-MMA)/C30B nanocomposites with various filler contents were characterized using elemental analysis, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), and atomic force microscopy. The effects of various C30B contents on the polymerization rate and monomer conversion of P(VAc-co-MMA)/C30B were studied. Thermal properties of the nanocomposite were studied by dynamic mechanical thermal analysis. The XRD and TEM results demonstrated that the synthesized polymer chains were aggregated into the C30B interlayer regions and consequently complete exfoliation was produced.     

Spinning and properties of poly(ethylene terephthalate)/organomontmorillonite nanocomposite fibers

By in situ polycondensation, a intercalated poly(ethylene terephthalate)/organomontmorillonite nanocomposite was prepared after montmorillonite (MMT) had been treated with a water‐soluble polymer. This nanocomposite was produced to fibers through melt spinning. The resulting nanocomposite fibers were characterized by X‐ray diffraction (XRD), differential scanning calorimeter (DSC), and transmission electron microscopy (TEM). The interlayer distance of MMT dispersed in the nanocomposite fibers was further enlarged because of strong shear stress during processing of melt spinning. This was confirmed by XRD test and TEM images. DSC test results showed that incorporation of MMT accelerated the crystallization of poly(ethylene terephthalate) (PET), but the crystallinity of the drawn fibers just had a little increasing compared with that of neat PET drawn fibers. Also compared with pure PET drawn fibers, tensile strength at 5% elongation and thermal stability of the nanocomposite fibers were improved. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1443–1447, 2005     

Synthesis,electrorheology, and creep behaviors of in situ intercalated polyindole/organo‐montmorillonite conducting nanocomposite

In this study, first polyindole (PIN) was synthesized using FeCl₃ as an oxidizing agent. Then, an organo‐montmorillonite (O‐MMT) was prepared from virgin montmorillonite (MMT) by cetyltrimethylammonium bromide (CTAB) quaternary ammonium salt. Further, PIN/O‐MMT conducting nanocomposite was prepared with 18% O‐MMT content. The samples of PIN, MMT, O‐MMT, and PIN/O‐MMT nanocomposite were characterized by FTIR spectroscopy, thermogravimetric analysis (TGA), X‐ray diffraction (XRD), elemental analysis, conductivity, magnetic susceptibility, density, particle size measurements, and scanning electron microscopy (SEM) method. Characterization results showed a successfully prepared PIN/O‐MMT nanocomposite having both intercalated and exfoliated structures. A series of concentrations (5–25%, m/m) were prepared from those above‐mentioned materials in silicone oil (SO) and their sedimentation stabilities were determined. The suspensions were subjected to an external electric field strength and electrorheological (ER) activity was observed. The effects of dispersed particle concentration, shear rate, external electric field strength, frequency, and temperature onto ER activities of these suspensions were investigated. Creep tests were applied to all the four suspensions and recoverable viscoelastic deformations observed. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

PLA/HTCC-MMT插层复合材料的绿色合成、表征及热降解动力学分析

以乳酸锌为绿色催化剂,采用丙交酯开环聚合法制备了聚乳酸/壳聚糖季铵盐改性蒙脱土(PLA/MMT HTCC)纳米复合材料。通过红外光谱、X射线衍射(XRD)、热重分析、扫描电子显微镜和透射电子显微镜进行了表征,采用Kissinger法和Ozawa法进行热降解动力学分析,得到材料的表观活化能。结果表明,PLA/MMT HTCC为插层型纳米复合材料, PLA/MMT HTCC的热分解峰值温度(Tp)比PLA最多高35.18 ℃,通过MMT HTCC插层的实现,材料的热分解活化能得到了提高,从而提高了其热稳定性。     

Effect of Layered Silicates on the Crystallinity and Mechanical Properties of HDPE/MMT Nanocomposite Blown Films

Summary The highdensitypolyethylene (HDPE)/montmorillonite (MMT) nanocomposites were prepared by melt blending using twin screw extruder with two step process. The master batches were manufactured by melt compounding with maleic anhydride grafted HDPE (HDPE-g-MAH) and MMT. The HPDE/MMT master batches were subsequently mixed with HDPE. The blown nanocomposite films were obtained by a single screw extruder attached film blowing and take-off unit. The MMT dispersion in the nanocomposite films was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The influence of MMT on the crystallinity, thermal properties and mechanical properties as a function of compatibilizer was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and universal testing machine, respectively. X-ray and TEM images showed the partially exfoliated nanocomposites which have the 5:1 – 20:1 ratios of HPDE-g-MAH and MMT. The thermal and mechanical properties of nanocomposites were enhanced by increasing the contents of MMT and in the presence of compatibilizer.     

Development of a gelatin-g-poly(acrylic acid-co-acrylamide)–montmorillonite superabsorbent hydrogels for in vitro controlled release of vitamin B12

Gelatin (Ge)-g-poly(acrylic acid-co-acrylamide) and montmorillonite (MMT)-clay-based nanocomposite hydrogels were fabricated to study the controlled release of vitamin B₁₂. Polymeric hydrogels were characterized with Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). FTIR spectroscopy confirmed the grafting of partially neutralized acrylic acid on a Ge backbone. The incorporation of MMT fillers inside the nanocomposite hydrogels and their increased crystallinity were established by XRD analysis. The rough surface morphologies of the composite hydrogels shown by SEM resulted from the assimilation of MMT inside the same. TEM confirmed the formation of nanosized composites. The average length and width of the MMT platelets were found to be 184.37 and 20.48 nm, respectively. The maximum swelling of the hydrogel was 375 g/g, and the results were established with Design-Expert software. The biodegradability of the nanocomposite increased in comparison to that of the copolymer hydrogel. Biocompatibility and cytotoxicity studies were also performed. During different time intervals, the controlled release of vitamin B₁₂ in artificial gastric fluid (AGF) and artificial intestinal fluid (AIF) was evaluated with a UV–visible spectrophotometer; this resulted in different controlled release curves. The release in AGF was 42%, and in AIF, the cumulative release was 80% over 6 h. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47596.     

Novel high-strength montmorillonite/polyvinyl alcohol composite film enhanced by chitin nanowhiskers

Nanomaterials can be used as reinforcement phase to improve the performance of polymers. A simple method to prepare a composite film with super high tensile strength was used in this study. The properties of montmorillonite (MMT)/polyvinyl alcohol (PVA) films reinforced by chitin nanowhisker (CNW) have been evaluated. The structures and properties of films were analyzed by atomic force microscope (AFM), Fourier transforms infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile testing. The results of FTIR and XRD showed that no chemical interaction occurred among MMT, PVA, and CNW. The SEM and AFM images suggested that the obtained composite films with the three substances had a relatively uniform layered structure and relatively smooth. The temperature at the onset of decomposition of the composite films was increased from 262.0 to 282.3°C by the addition of CNW. The tensile strength of the MMT/PVA/CNW film was reached 263.5 MPa, which was increased approximately 382% compared with the MMT/PVA film. According to these results, the composite film could be potentially used in packaging materials.     

Harmless hydrogels based on PVA/Na+‐MMT nanocomposites for biomedical applications: Fabrication and characterization

A series of nanocomposite hydrogels were prepared by a freeze‐thaw process, using polyvinyl alcohol (PVA) as polymer matrix and 0–10 wt% of hydrophilic natural Na‐montmorillonite (Na⁺‐MMT), free from any modification, as composite aggregates. The effect of nanoclay content and the sonication process on the nanocomposite microstructure and morphology as well as its properties (physical, mechanical, and thermal) were investigated. The microstructure and morphology were investigated by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and X‐ray diffraction technique. The thermal stability and mechanical properties of nanocomposite hydrogels were examined using thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis; moreover hardness and water vapor transmission rate measurements. It was concluded that the microstructure, morphology, physical (thermal) and mechanical properties of nanocomposite hydrogels have been modified followed by addition of nanoclay aggregates. The results showed that Na⁺‐MMT may act as a co‐crosslinker. Based on the results obtained, the nanocomposite hydrogel PVA/Na⁺‐MMT synthesized by a freeze‐thaw process, appeared to be a good candidate for biomedical applications. POLYM. COMPOS., 38:1135–1143, 2017. © 2015 Society of Plastics Engineers     

Synthesis and characterization of partially hydrolyzed polyacrylamide nanocomposite weak gels with high molecular weights

High‐molecular‐weight partially hydrolyzed polyacrylamide nanocomposite (HPAMNC) weak gels were synthesized and evaluated for their flooding behaviors in oil‐recovery applications. The structure, morphology, and properties of the obtained HPAMNC samples and their weak gels were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). XRD patterns clearly proved the exfoliation of the montmorillonite (MMT) layers in the polymer matrix; this was consistent with TEM analysis. The morphology of the HPAMNC was proven to be in a cross‐wire aggregated form by SEM analysis. The viscosity‐average molecular mass of the obtained HPAMNC was approximately 8.51 × 10⁶ under the optimized MMT load at 1.0 wt %. The flooding experiments showed that the oil‐recovery rates in sand pack tubes with low and high permeability were enhanced by approximately 35.1 and 46.2%, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42626.     

Effect of montmorillonite on the swelling behavior and drug‐release behavior of nanocomposite hydrogels

A series of nanocomposite hydrogels were prepared from various ratios of N‐isopropylacrylamide (NIPAAm) and organic montmorillonite (MMT). The influence of the extent of MMT in the NIPAAm/MMT nanocomposite hydrogels on the physical properties and drug‐release behavior was the main purpose of this study. The microstructure and morphology were identified by X‐ray diffraction (XRD) and scanning electronic microscopy (SEM). The results showed that the swelling ratios for these nanocomposite hydrogels decreased with increase in the content of MMT. The gel strength and Young's modulus of the gels also increased with increase in the content of MMT. XRD results indicated that the exfoliation of MMT was achieved in the swollen state. Finally, the drug‐release behavior for the gels was also assessed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3652–3660, 2003     

High strength poly(acrylamide)-clay hydrogels

A series of polyacrylamide nanocomposite hydrogels were synthesized by in situ free radical polymerization of acrylamide (AAm) with ethylene glycol dimethacrylate (EGDMA) as a crosslinker in the presence of sodium montmorillonite (NaMMT) and organically modified montmorillonite (OrgMMT) clays. Modification of MMT was carried out with a quaternary salt of coco amine as intercalant having a styryl group whose contribution to both polymerization and crosslinking reactions via its reactive double bond was confirmed by solid state NMR. Exfoliation success was checked with X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques whereas mechanical performance was followed with uniaxial compression experiment. It has been found that exfoliated PAAm nanocomposites having 0.5% OrgMMT had both the maximum equilibrium swelling in water and compression strength as well as improved thermal stability due to the special and beneficial morphology observed via scanning electron microscopy (SEM).