Poly(styrene‐b‐tetrahydrofuran)/clay nanocomposites by mechanistic transformation

Synthesis of poly(styrene‐block‐tetrahydrofuran) (PSt‐b‐PTHF) block copolymer on the surfaces of intercalated and exfoliated silicate (clay) layers by mechanistic transformation was described. First, the polystyrene/montmorillonite (PSt/MMT) nanocomposite was synthesized by in situ atom transfer radical polymerization (ATRP) from initiator moieties immobilized within the silicate galleries of the clay particles. Transmission electron microscopy (TEM) analysis showed the existence of both intercalated and exfoliated structures in the nanocomposite. Then, the PSt‐b‐PTHF/MMT nanocomposite was prepared by mechanistic transformation from ATRP to cationic ring opening polymerization (CROP). The TGA thermogram of the PSt‐b‐PTHF/MMT nanocomposite has two decomposition stages corresponding to PTHF and PSt segments. All nanocomposites exhibit enhanced thermal stabilities compared with the virgin polymer segments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2190–2197, 2009     

Synthesis of polybenzoxazine/clay nanocomposites by in situ thermal ring‐opening polymerization using intercalated monomer

A new class of polybenzoxazine/montmorillonite (PBz/MMT) nanocomposites has been prepared by the in situ polymerization of the typical fluid benzoxazine monomer, 3‐pentyl‐5‐ol‐3,4‐dihydro‐1,3‐benzoxazine, with intercalated benzoxazine MMT clay. A pyridine‐substituted benzoxazine was first synthesized and quaternized by 11‐bromo‐1‐undecanol and then used for ion exchange reaction with sodium ions in MMT to obtain intercalated benzoxazine clay. Finally, this organomodified clay was dispersed in the fluid benzoxazine monomers at different loading degrees to conduct the in situ thermal ring‐opening polymerization. Polymerization through the interlayer galleries of the clay led to the PBz/MMT nanocomposite formation. The morphologies of the nanocomposites were investigated by both X‐ray diffraction and transmission electron microscopic techniques, which suggested the partially exfoliated/intercalated structures in the PBz matrix. Results of thermogravimetric analysis confirmed that the thermal stability and char yield of PBz nanocomposites increased with the increase of clay content. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Encapsulated clay particles in polystyrene by RAFT mediated miniemulsion polymerization

RAFT grafted montmorillonite (MMT) clays [i.e., N,N‐dimethyl‐N‐(4‐(((phenylcarbonothioyl)thio)methyl)benzyl)ethanammonium‐MMT (PCDBAB‐MMT) and N‐(4‐((((dodecylthio)carbonothioyl)thio)methyl)benzyl)‐N,N‐dimethylethanammo‐nium‐MMT (DCTBAB‐MMT)] of various loadings were dispersed in styrene (S) monomer and the resultant mixtures emulsified and sonicated in the presence of a hydrophobe (hexadecane) into miniemulsions. The stable miniemulsions thus obtained were polymerized to yield encapsulated polystyrene‐clay nanocomposites (PS‐CNs). The molar mass and polydispersity index (PDI) of the PS‐CNs depended on the amount of RAFT agent in the system, in accordance with the features of the RAFT process. The morphology of the PS‐CNs ranged from partially exfoliated to an intercalated morphology, depending on the percentage clay loading. The thermomechanical properties of the PS‐CNs were better than those of the neat PS polymer, and were dependent on the molar mass, PS‐CN morphology and clay loading. The similarities and differences of the PS‐CNs prepared here by miniemulsion polymerization were compared to those prepared using the same RAFT agents and polymer system by bulk polymerization (as reported by us in a previous article). © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7114–7126, 2008     

Synthesis of poly(methyl methacrylate) nanocomposites via emulsion polymerization using a zwitterionic surfactant

The synthesis of nanocomposites via emulsion polymerization was investigated using methyl methacrylate (MMA) monomer, 10 wt % montmorillonite (MMT) clay, and a zwitterionic surfactant octadecyl dimethyl betaine (C18DMB). The particle size of the diluted polymer emulsion was about 550 nm, as determined by light scattering, while the sample without clay had a diameter of about 350 nm. The increase in the droplet size suggests that clay was present in the emulsion droplets. X-ray diffraction indicated no peak in the nanocomposites. Transmission electron microscopy showed that emulsion polymerization of MMA in the presence of C18DMB and MMT formed partially exfoliated nanocomposites. Differential scanning calorimetry showed an increase of 18 degrees C in the glass transition temperature (Tg) of the nanocomposites. A dynamic mechanical thermal analyzer also verified a similar Tg increase, 16 degrees C, for the partially exfoliated nanocomposites over poly(methyl methacrylate) (PMMA). Thermogravimetric analysis indicated a 37 degrees C increase in the decomposition temperature for a 20 wt % loss. A PMMA nanocomposite with 10 wt % C18DMB-MMT was also synthesized via in situ polymerization. This nanocomposite was intercalated and had a Tg 10 degrees lower than the emulsion nanocomposite. The storage modulus of the partially exfoliated emulsion nanocomposite was superior to the intercalated structure at higher temperatures and to the pure polymer. The rubbery plateau modulus was over 30 times higher for the emulsion product versus pure PMMA. The emulsion technique produced nanocomposites of the highest molecular weight with a bimodal distribution. This reinstates that exfoliated structures have enhanced thermal and mechanical properties over intercalated hybrids.     

蒙脱土负载型引发剂的制备及在苯乙烯乳液聚合中的应用

通过正离子交换将引发剂AIBA负载在蒙脱土上制得负载型引发剂V50-MMT.进而采用原位乳液聚合方法引发苯乙烯聚合制备PS/MMT纳米复合材料.采用XRD、TGA、DSC、TEM和抽提等方法对负载型引发剂和纳米复合材料进行了表征.结果表明,负载过程中引发剂AIBA进入了MMT的片层之间;聚合过程中介于片层间的引发剂因发生分解一方面产生自由基引发St聚合,另一方面MMT发生了剥离分散;由此法制备的PS/MMT纳米复合材料,MMT片层无规、均匀地分散于PS基体中,片层厚度在几个纳米至十几个纳米之间,长度为几十至几百个纳米不等;大量的PS链段以化学键接枝在MMT的片层上,接枝在MMT片层上的PS的分子量及其分布与游离的PS不同.     

Impact of the clay organic modifier on the morphology of polymer–clay nanocomposites prepared by in situ free‐radical polymerization in emulsion

Poly(styrene‐co‐butyl acrylate) copolymers were prepared by free‐radical random copolymerization of styrene and butyl acrylate in emulsion in the presence of 10% of surface‐modified sodium montmorillonite (Na‐MMT). The objective of this work was to evaluate the impact of the clay organic modifier in terms of its chemical structure, its degree of interaction within the clay galleries surface, and its ability to copolymerize with monomers, on the morphology and properties of the final nanocomposite prepared. Na‐MMT was modified using different organic modifiers, namely: sodium 1‐allyloxy‐2‐hydroxypropyl (Cops), 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS), N‐isopropylacrylamide (NIPA), and sodium 11‐methacryloyloxy‐undecan‐1‐yl sulfate (MET), respectively. The morphology and properties of the nanocomposites obtained were found to be dependant on the clay organic modifier. X‐ray diffraction (XRD) and transmission electron microscopy indicated that, nanocomposites at 10% clay loading with Cops‐, NIPA‐, and MET‐modified clays, yielded intercalated to partially exfoliated structures, whereas AMPS‐modified clay gave a nanocomposite with a fully exfoliated structure. All polymer–clay nanocomposites were found to be more thermally stable than neat poly(S‐co‐BA) as were determined by TGA. However, nanocomposites with intercalated structures exhibited greater thermal stability relative to fully exfoliated ones. Furthermore, nanocomposites with exfoliated structures exhibited higher storage moduli (G^I) than partially exfoliated once, whereas intercalated structure showed the lowest G^I values. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3619–3628, 2008     

Thermal properties of polystyrene nanocomposites formed from rigid intercalation agent‐treated montmorillonite

Polystyrene (PS)/clay nanocomposites were prepared with two different new intercalation organophilic clays, the phosphonium salt (APP) and the ammonium 4‐(4‐adamantylphenoxy)‐1‐butanamine (APB) salts, by emulsion polymerization technique. X‐ray diffraction and transmission electron microscopy were performed to characterize the layered structures of APB‐ and APP‐treated polymer–clay nanocomposites, and both resulted in exfoliated structures. Molecular weights of PS obtained from these nanocomposites are slightly lower than the virgin PS formed under similar polymerization conditions. Coefficient of thermal expansion showed approximately a 44–55% decrease for APB‐ and APP‐intercalated clay nanocomposites relative to the pure PS. Both T_g and thermal decomposition temperature of the PS component in the nanocomposite are higher than the virgin PS, implying that the presence of clay is able to enhance thermal stabilities of the PS. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1781–1787, 2007     

Preparation of thermosetting polyurethane nanocomposites by montmorillonite modified with a novel intercalation agent

A novel thermosetting polyurethane (TSPU)/organic montmorillonite (OMMT) nanocomposite has been synthesized. N‐diamino octadecyl trimethyl ammonium chloride (DODTMAC) was used as an intercalation agent to treat Na⁺‐montmorillonite (MMT) and form a novel kind of OMMT. Fourier transform infrared spectroscopy (FT‐IR), wide angle X‐ray diffraction (WAXD), and thermogravimetric analysis (TGA) data indicated that the MMT was successfully intercalated by this intercalation agent, as evidenced by the fact that the basal spacing of MMT galleries was expanded from 1.5 to 3.2 nm. This OMMT was used to prepare the TSPU nanocomposites. Both the reinforcing and compatibilizing performance of the filler were investigated. Tensile tests showed that the tensile strength of TSPU/OMMT‐4 was the highest, and was about 3.62 times higher than that of the pure TSPU, and also the elongation at break showed an enhancement. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) measurements illustrated that the glass transition temperature of the TSPU/OMMT‐4 nanocomposite was improved from 0.5 to 6.5 °C, which corresponded to the restriction of the soft segments of TSPU. The highest initial and center temperatures of TSPU/OMMT‐4 obtained from TGA were due to the highest retard effect of the TSPU molecular chains. WAXD studies showed that the formation of the nanocomposites in all the cases with the almost disappearance of the peaks corresponding to the basal spacing of MMT. SEM and TEM were used to investigate the morphologies of the TSPU/OMMT‐4 nanocomposite, and demonstrated that the nanocomposite was comprised of a well dispersion of a mixture of intercalated and exfoliated silicate layers throughout the matrix. It was proposed that the nano‐reinforcing effect caused by the well‐dispersed silicate layers might reduce the amount and size of voids and increase the length of the crack‐spreading path during tensile drawing. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 519–531, 2007.     

Synthesis and characterization of polymer/clay nanocomposites by intercalated chain transfer agent

In situ synthesis of poly(methyl methacrylate) (PMMA) and polystyrene (PS) nanocomposites by free radical polymerization using intercalated chain transfer agent (I-CTA) in the layers of montmorillonite (MMT) clay is reported. MMT clay was ion-exchanged with diethyl octyl ammonium ethylmercaptan bromide, which acts both as suitable intercalant and as chain transfer agent. These modified clays were then dispersed in methyl methacrylate (MMA) or styrene (St) monomers in different loading degrees to carry out the in situ free radical polymerization. The intercalation ability of the chain transfer agent and exfoliated nanocomposite structure were evidenced by both X-ray diffraction spectroscopy (XRD) and transmission electron microscopy (TEM). Thermal properties and morphologies of the resultant nanocomposites were also studied.     

乳液聚合法制备剥离型PS/MMT纳米复合材料

以阳离子表面活性剂十八烷基三甲基氯化铵(OTAC)和烯丙基十八烷基二甲基氯化铵(ATAC)为插层处理剂改性蒙脱土(MMT),原位乳液聚合分别制备了PS/C18MMT和PS/AC18MMT两种纳米复合材料.XRD和TEM分析表明,MMT均被剥离成单个或几个片层无规的分散在PS基体中,TGA分析表明,MMT的加入提高了材料的耐热性能,当PS基体与有机化处理的MMT片层发生一定的化学连接后,PS/AC18MMT纳米复合材料表现出更好的耐热性能.动态力学分析表明,MMT的加入提高了PS的玻璃态储能模量,降低了材料的动态损耗;PS/AC18MMT纳米复合材料的玻璃化温度较PS有所提高,而PS/C18MMT的玻璃化温度与PS相比略有降低.     

Synthesis and characterization of organosoluble,thermoplastic elastomer/clay nanocomposites

We synthesized organosoluble, thermoplastic elastomer/clay nanocomposites by making a jelly like solution of ethylene vinyl acetate containing 28% vinyl acetate (EVA‐28) and blending it with organomodified montmorillonite. Sodium montmorillonite (Na⁺‐MMT) was made organophilic by the intercalation of dodecyl ammonium ions. X‐ray diffraction patterns of Na⁺‐MMT and its corresponding organomodified dodecyl ammonium ion intercalated montmorillonite (12Me‐MMT) showed an increase in the interlayer spacing from 11.94 to 15.78 Å. However, X‐ray diffraction patterns of the thermoplastic elastomer and its hybrids with organomodified clay contents up to 6 wt % exhibited the disappearance of basal reflection peaks within an angle range of 3–10°, supporting the formation of a delaminated configuration. A hybrid containing 8 wt % 12Me‐MMT revealed a small hump within an angle range of 5–6° because of the aggregation of silicate layers in the EVA‐28 matrix. A transmission electron microscopy image of the same hybrid showed 3–5‐nm 12Me‐MMT particles dispersed in the thermoplastic elastomer matrix; that is, it led to the formation of nanocomposites or molecular‐level composites with a delaminated configuration. The formation of nanocomposites was reflected through the unexpected improvement of thermal and mechanical properties; for example, the tensile strength of a nanocomposite containing only 4 wt % organophilic clay was doubled in comparison with that of pure EVA‐28, and the thermal stability of the same nanocomposite was higher by about 34 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2065–2072, 2002     

Pendant cyclic carbonate‐polymer/Na‐smectite nanocomposites via in situ intercalative polymerization and solution intercalation

Nanocomposites of sodium smectite with polyether‐ and polystyrene‐containing pendant cyclic carbonates offer a novel approach to improving hydraulic barrier properties of Na‐smectite liners to saline leachates. The cyclic carbonate polyethers were prepared by cationic ring opening polymerization of a cyclic carbonate‐containing epoxide, whilst polystyrene polymers having pendant cyclic carbonate groups were obtained from radical photopolymerization of styrene. Na‐smectite nanocomposites of these polymers were formed via clay in situ polymerization and solution intercalation methods. X‐ray diffraction (XRD) and FT‐IR analysis confirmed that the polyether can be intercalated within the layers of smectite via in situ as well as solution intercalation of the pre‐formed polymer. The cyclic carbonate polyether nanocomposite was more resistant to leaching in 3M aqueous sodium chloride than its respective cyclic carbonate. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2421–2429     

In situ intercalative polymerization of conducting polypyrrole/montmorillonite nanocomposites

Conducting polypyrrole (PPy)‐montmorillonite (MMT) clay nanocomposites have been synthesized by the in situ intercalative polymerization method. The PPy‐MMT nanocomposites are characterized by field‐emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), ultraviolet–visible (UV–vis) spectroscopy, thermogravimetric analysis (TGA), and Fourier‐transform infrared (FTIR) spectroscopy. XRD patterns show that after polymerization by the in situ intercalative method with ammonium persulfate and 1 M HCl, an increase in the basal spacing from 1.2 to 1.9 nm was observed, signifying that PPy is synthesized between the interlayer spaces of MMT. TEM and SEM micrographs suggest that the coexistence of intercalated MMT layers with the PPy macromolecules. FTIR reveals that there might be possible interfacial interactions present between the MMT clay and PPy matrix. The study also shows that the introduction of MMT clay results in thermal stability improvement of the PPy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2279–2285, 2008     

The influence of multiple modified MMT on the thermal and fire behavior of poly (lactic acid) nanocomposites

This work reported the preparation and physical properties of biodegradable nanocomposites fabricated using polylactic acid (PLA) and multiple organic modified montmorillonite (MMT). In order to improve the chemical compatibility between PLA and Na‐MMT, the surface of Na‐MMT was first organically modified by cetyl trimethyl ammonium bromide (CTAB) and resorcinol bis(diphenyl phosphate) (RDP) using ion‐exchange and adsorption technique. Both Fourier transform infrared and X‐ray diffraction (XRD) results indicated that CTAB and RDP molecules were intercalated into the galleries of MMT sheets to enlarge the interlayer spacing. Then, the PLA/MMT nanocomposites were prepared by a simple melt‐blending method. The XRD and TEM results of the nanocomposites indicated that the PLA polymer chains inserted into the galleries of co‐modified MMT (C‐MMT) and contained disorderedly intercalated layered silicate layers within a PLA matrix. The C‐MMT nanolayers were homogenously dispersed in PLA matrix, resulting in various property enhancement. The fabricated PLA/C‐MMT nanocomposites with 5.0 wt% addition showed significant enhancements (176%) in the storage modulus compared to that of neat PLA. The thermal stability and fire resistance were also remarkably improved. These improvements are probably because of both the physical barrier effect of the MMT nanosheets and charring effect of the C‐MMT. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis of exfoliated polystyrene/montmorillonite nanocomposite by emulsion polymerization using a zwitterion as the clay modifier

Montmorillonite (MMT) was modified with zwitterion aminoundecanoic acid (AUA). First AUA was protonized to facilitate molecules to get into the galleries of the montmorillonite to accomplish ion exchange, and the carboxyl groups were then ionized in the alkaline aqueous media to enable exfoliation of the clay. It was demonstrated by rheological measurements and atomic force microscopic studies that exfoliation of the clay driven by the electrostatic repulsion took place in an alkaline medium. Polystyrene/montmorillonite (PS/MMT) nanocomposite was synthesized via emulsion polymerization in the presence of the modified MMT. The exfoliated microstructure of the composites was studied by the X-ray diffraction and transmission electron microscopy. The exfoliated PS/MMT nanocomposite showed a greatly improved modulus, a higher glass transition temperature and a better thermal stability compared to the neat polystyrene and the intercalated PS/MMT composites.     

Effects of organoclays on morphology and thermal and rheological properties of polystyrene and poly(methyl methacrylate) blends

Morphology, thermal and rheological properties of polymer‐organoclay composites prepared by melt‐blending of polystyrene (PS), poly(methyl methacrylate) (PMMA), and PS/PMMA blends with Cloisite® organoclays were examined by transmission electron microscopy, small‐angle X‐ray scattering, secondary ion mass spectroscopy, differential scanning calorimetry, and rheological techniques. Organoclay particles were finely dispersed and predominantly delaminated in PMMA‐clay composites, whereas organoclays formed micrometer‐sized aggregates in PS‐clay composites. In PS/PMMA blends, the majority of clay particles was concentrated in the PMMA phase and in the interfacial region between PS and PMMA. Although incompatible PS/PMMA blends remained phase‐separated after being melt‐blended with organoclays, the addition of organoclays resulted in a drastic reduction in the average microdomain sizes (from 1–1.5 μm to ca. 300–500 nm), indicating that organoclays partially compatibilized the immiscible PS/PMMA blends. The effect of surfactant (di‐methyl di‐octadecyl‐ammonia chloride), used in the preparation of organoclays, on the PS/PMMA miscibility was also investigated. The free surfactant was more compatible with PMMA than with PS; the surfactant was concentrated in PMMA and in the interfacial region of the blends. The microdomain size reduction resulting from the addition of organoclays was definitely more significant than that caused by adding the same amount of free surfactant without clay. The effect of organoclays on the rheological properties was insignificant in all tested systems, suggesting weak interactions between the clay particles and the polymer matrix. In the PS system, PMMA, and organoclay the extent of clay exfoliation and the resultant properties are controlled by the compatibility between the polymer matrix and the surfactant rather than by interactions between the polymer and the clay surface. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 44–54, 2003     

Exploitation of introducing of catalytic centers into layer galleries of layered silicates and related epoxy nanocomposites. I. Epoxy nanocomposites derived from montmorillonite modified with catalytic surfactant‐bearing carboxyl groups

Montmorillonite (MMT) was modified with the acidified cocamidopropyl betaine (CAB) and the resulting organo‐montmorillonite (O‐MMT) was dispersed in an epoxy/methyl tetrahydrophthalic anhydride system to form epoxy nanocomposites. The intercalation and exfoliation behavior of the epoxy nanocomposites were examined by X‐ray diffraction and transmission electron microscopy. The curing behavior and thermal property were investigated by in situ Fourier transform infrared spectroscopy and DSC, respectively. The results showed that MMT could be highly intercalated by acidified CAB, and O‐MMT could be easily dispersed in epoxy resin to form intercalated/exfoliated epoxy nanocomposites. When the O‐MMT loading was lower than 8 phr (relative to 100 phr resin), exfoliated nanocomposites were achieved. The glass‐transition temperatures (T_g's) of the exfoliated nanocomposite were 20 °C higher than that of the neat resin. At higher O‐MMT loading, partial exfoliation was achieved, and those samples possessed moderately higher T_g's as compared with the neat resin. O‐MMT showed an obviously catalytic nature toward the curing of epoxy resin. The curing rate of the epoxy compound increased with O‐MMT loading. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1192–1198, 2004     

Studies on the conducting nanocomposite prepared by in situ polymerization of aniline monomers in a neat (aqueous) synthetic mica clay

The in situ polymerization of the anilinium‐intercalated synthetic mica clay can easily result in an intercalated polyaniline (PANI)/clay nanocomposite. The FT‐IR spectra demonstrated a significant shift for ν_{(C? N)} at 1292 cm^?1 of the templated polymerized and intercalated PANI molecules. A red shift of λ_max for PANI was found from UV–vis spectra. The intercalated PANI also expanded the clay basal spacing seen from WAXD patterns. The degradation rate and temperature of the nanocomposites were found to alleviate and increase compared to neat PANI, respectively. The microscopic examinations including TEM, SEM, and AFM pictures of the nanocomposite demonstrated an entirely different and more compatible morphology. Conductivity of nanocomposite gradually increased with PANI and apparent increase was found when intercalated PANI content reached 40.6 wt %, the possible percolation threshold. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1800–1809, 2008     

Swelling behavior of organoclays in styrene and exfoliation in nanocomposites

Organoclays were prepared by cationic exchange of montmorillonite (MMT) with three commercial surfactants: octadecylamine (ODA), hexadecyltrimethylammonium bromide (HTAB), benzalkonium chloride (BAC), and an in-house synthesized surfactant, vinylbenzylalkyldimethylammonium chloride (VDAC). The swelling behaviors of organoclays in styrene were compared by wettability and rheology measurements. VDAC-MMT had the slowest capillary rise rate in styrene. The Washburn equation was found not suitable for the swellable organoclay powders. All organoclay-styrene and organoclay-toluene mixtures demonstrated yield stress. However, VDAC-MMT-styrene and VDAC-MMT-toluene mixtures showed significant higher yield stresses than the other organoclay mixtures. The wettability and rheology measurements indicate that VDAC-MMT bearing a styryl functional group has the strongest interaction with styrene monomer and toluene. In order to further evaluate the extent of swelling and the microstructure, polystyrene (PS)-clay nanocomposites were prepared by in situ polymerization. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicate that ODA and HTAB-MMT led to intercalated PS-clay nanocomposites, while VDAC-MMT formed exfoliated PS-clay nanocomposites.     

Amine‐cured epoxy/clay nanocomposites. I. Processing and chemical characterization

The processing of nanocomposite materials composed of amine‐cured diglycidyl ether of bisphenol A (DGEBA) reinforced with organomontmorillonite clay is reported. A novel sample preparation scheme was used to process the modified clay in the glassy epoxy network, resulting in nanocomposites where the clay was both exfoliated and intercalated by the epoxy network. The processing scheme involves sonication of the constituent materials in a solvent, followed by solvent extraction to generate a composite with homogeneous dispersions of the nanoclay. Fourier transform infrared spectroscopy (FTIR) and Fourier transform (FT‐)Raman spectroscopy confirmed that the chemical structure of the epoxy network was not affected by the use of solvents in this processing scheme. The glass‐transition temperature, T_g, linearly increased with an increased weight ratio of the nanoclay. The microstructure of clay nanoplatelets in the composites was observed with transmission electron microscopy (TEM), wide‐angle X‐ray scattering (WAXS), and small‐angle X‐ray scattering (SAXS). It was found that the clay nanoplatelets were well‐dispersed, and were intercalated as well as exfoliated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4384–4390, 2004