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     

Styrene–butadiene–styrene/montmorillonite nanocomposites synthesized by anionic polymerization

We successfully synthesized an exfoliated styrene–butadiene–styrene triblock copolymer (SBS)/montmorillonite nanocomposite by anionic polymerization. Gel permeation chromatography showed that the introduction of organophilic montmorillonite (OMMT) resulted in a small high‐molecular‐weight fraction of SBS in the composites, leading to a slight increase in the weight‐average and number‐average molecular weights as well as the polydispersity index. The results from ¹H‐NMR revealed that the introduction of OMMT almost did not affect the microstructure of the copolymer when the OMMT concentration was lower than 4 wt %. Transmission electron microscopy and X‐ray diffraction showed a completely exfoliated nanocomposite, in which both polystyrene and polybutadiene blocks entered the OMMT galleries, leading to the dispersion of OMMT layers on a nanoscale. The exfoliated nanocomposite exhibited higher thermal stability, glass‐transition temperature, elongation at break, and storage modulus than pure SBS. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Antimicrobial N‐halamine coatings synthesized via vapor‐phase assisted polymerization

An N‐halamine monomer, 3‐allyl‐5,5‐dimethylhydantoin (ADMH), was synthesized by a Gabriel reaction of 5,5‐dimethylhydantoin and 3‐bromopropene. Antimicrobial coatings of poly[1‐(4,4‐dimethyl‐2,5‐dioxoimidazolidin‐1‐methyl)ethylene] were prepared on plasma‐treated PET fabrics via a vapor‐phase assisted polymerization (VAP) process using gasified ADMH as monomer. The coatings endow the PET fabrics with an antimicrobial efficiency greater than 80% for both Escherichia coli and Staphylococcus aureus after chlorination of the N‐halamine polymer with dilute bleach solution. The obtained antimicrobial effect has remarkable durability that can bear over 30 times of stringent laundering tests. Compared with other antimicrobial finishing methods, the VAP methodology offers great advantages in needless of organic solvents and small consumption of monomer. It has potential applications in a wide variety of fields such as hygienic clothing, underwear, socks, and medical textiles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41824.     

Properties of high‐impact polystyrene/organoclay nanocomposites synthesized via in situ polymerization

High‐impact polystyrene (HIPS)/organically modified montmorillonite (organoclay) nanocomposites were synthesized via in situ polymerization. The effects of the organoclay on the morphology and material properties of HIPS/organoclay nanocomposites were investigated. X‐ray diffraction and transmission electron microscopy experiments revealed that intercalation of polymer chains into silicate layers was achieved, and the addition of nanoclay led to an increase in the size of the rubber domain in the composites. In comparison with neat HIPS, the HIPS/organoclay nanocomposites exhibited improved thermal stability as well as an increase in both the complex viscosity and storage modulus. The presence of intercalated organoclay drastically enhanced the gas‐barrier properties because of the increase in the tortuosity of the diffusive path for a penetrating gas molecule. Some mechanical properties, including the tensile modulus, were superior to those of conventional HIPS. Finally, the preparation of the nanocomposites with a minimal loss of impact properties was proposed through changes in the synthetic procedure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Core/shell SiOx@PAM nanospheres from UV‐assisted surface‐initiated free radical polymerization

The core/shell SiO_x@polyacrylamide (SiO_x@PAM) nanospheres were successfully prepared by the in situ surface‐initiated free radical polymerization of acrylamide (AM) from the silica nanoparticles with self‐assembled monolayers (SAMs) of N‐methyl aniline (NMA) in presence of benzophonone via a precipitation polymerization method under the ultraviolet (UV) irradiation. The conversion of monomer (C%) and the percentage of encapsulating (PE%), calculated from the elemental analyses (EA) results, reached 20.9 and 51.0% after 150 min of UV‐irradiation, respectively. It is consistent with the analyses of TGA. Fourier transform infrared (FTIR) analyses also confirmed the formation of the core/shell SiO_x@PAM nanospheres. And it was investigated that the silica nanoparticles had been encapsulated with PAM from the X‐ray photoelectron spectrometer (XPS) analyses. The analysis results of transmission electron microscope (TEM) showed that the diameters of the SiO_x@PAM nanospheres were in the range of 50–200 nm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3433–3438, 2006     

Supercritical CO2‐assisted synthesis of polystyrene/clay nanocomposites via in situ intercalative polymerization

Cyclodextrins can form inclusion complexes with different molecules with the aid of their special chemical (molecular) structures. Physical and chemical properties of molecules can change after the formation of complex. This special feature enables the usage of dextrins in different industry areas. In this study, applicability of cylcodextrins in textile dyeing and washing processes was investigated. With this aim, β‐cyclodextrin was used in direct dyeing of cellulosic fabrics and in rinsing processes of direct dyed fabrics. Retarder/leveling effect of β‐cyclodextrin in dyeing process has been studied and the results were compared with that of a commercial product. In general, cyclodextrins were used in washing processes to remove the absorbed surfactants. It has been investigated whether this effect was the same for washing of dyed fabrics. Eight different direct dyes, for which the chemical structures are known, were used in dyeing and washing processes, and effect of β‐cyclodextrin on different chemical structures was investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 208–218, 2006     

Preparation of silica/polyurethane nanocomposites by UV‐induced polymerization from surfaces of silica

UV‐curable nanocomposites were prepared by the in situ photopolymerizaton with nanosilica obtained from sol–gel process. The photoinitiator 2‐hydroxy‐2‐methyl‐1‐phenylpropane‐1‐one (1173) was anchored onto the surface of the nanosilica with or without methacryloxypropyltrimethoxysilane (MAPS) modification. The photopolymerization kinetics was studied by real‐time Fourier transform IR (RTIR), and the microstructure and properties of the nanocomposite were investigated using transmission electron microscopy and UV–visible (UV–vis) transmistance spectra. RTIR analysis indicated that the nanocomposites without MAPS had higher curing rates and final conversion than those with MAPS. The nanocomposites with an uniformal dispersion of nanosilica had high UV–vis transmittance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of polystyrene/poly(vinyl acetate) nanocomposites with a core–shell structure via emulsifier‐free emulsion polymerization

Polystyrene/poly(vinyl acetate) latex nanoparticles with a core–shell morphology in an emulsifier‐free emulsion polymerization system were prepared with purified styrene and vinyl acetate (VAc) as monomers and 2,2′‐azo bis(2‐amino propane) dihydrochloride (ABA,2HCl) as the initiator and emulsifier. The optimized conditions of polymerization of VAc, on top of the already‐formed polystyrene as a core polymer, with a core–shell morphology were obtained using various parameters such as volume ratio of the first and second stages, type of process, and reaction time. The morphologic structure of the nanoparticles was studied by scanning electron microscopy and transmission electron microscopy. The latex nanoparticles and polymers were characterized by differential scanning calorimetry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2409–2414, 2006     

New clay‐supported Ziegler–Natta catalyst for preparation of PE/Clay nanocomposites via in situ polymerization

Polyethylene/clay (PE/Clay) nanocomposites were prepared by the in situ polymerization of ethylene using the new Clay/butyl octyl magnesium (BOM)/Chloroform/EtOH/TiCl₄/tri ethyl aluminum (TEA) catalyst system in heptane where BOM and TEA were the support for the clay modification and cocatalyst, respectively. The influence of the modified clay using BOM on the catalyst and polymerization was investigated. Also, the effect of temperature, pressure, hydrogen, and the molar ratios of TEA/Ti on the catalyst yield and ethylene consumption (polymerization rate) were studied. It was found that the above clay‐supported catalyst was an efficient Ziegler–Natta type catalyst due to its suitable yield for the polymerization of ethylene toward the production of the PE/Clay nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of polystyrene–clay nanocomposites via dispersion polymerization using oligomeric styrene‐montmorillonite as stabilizer

This study describes the preparation of polystyrene–clay nanocomposite (PS‐nanocomposite) colloidal particles via free‐radical polymerization in dispersion. Montmorillonite clay (MMT) was pre‐modified using different concentrations of cationic styrene oligomeric (‘PS‐cationic’), and the subsequent modified PS‐MMT was used as stabilizer in the dispersion polymerization of styrene. The main objective of this study was to use the clay platelets as fillers to improve the thermal and mechanical properties of the final PS‐nanocomposites and as steric stabilizers in dispersion polymerization after modification with PS‐cationic. The correlation between the degree of clay modification and the morphology of the colloidal PS particles was investigated. The clay platelets were found to be encapsulated inside PS latex only when the clay surface was rendered highly hydrophobic, and stable polymer latex was obtained. The morphology of PS‐nanocomposite material (after film formation) was found to range from partially exfoliated to intercalated structure depending on the percentage of PS‐MMT loading. The impact of the modified clay loading on the monomer conversion, the polymer molecular weight, the thermal stability and the thermomechanical properties of the final PS‐nanocomposites was determined. Copyright © 2012 Society of Chemical Industry     

Kinetic and thermomechanical analysis of hydrophobic–hydrophilic copolymer thermosets synthesized via free‐radical polymerization

The synthesis of a crosslinked copolymer of hydrophobic and hydrophilic monomers, diglycidyl ether of bisphenol A vinyl ester (VE), and 2‐acrylamido 2‐methyl 1‐propane sulfonic acid (AMPS) respectively, is discussed. A methodology for real‐time monitoring of the copolymerization reaction using transmission mode near infrared (NIR) spectroscopy was employed that resolves overlapping peaks associated with the reactive double bonds. The influence of solvent, monomer ratio, and initiator concentration on the kinetic behavior of the system was investigated. The method of Mayo and Lewis was used to provide a qualitative understanding of the microstructure being formed. At low conversions (<15%) and within the compositions of interest, greater VE homopolymerization as compared with AMPS homopolymerization was observed and the product of the reactivity ratios (r_AMPS.r_VE) was close to 0.5, suggesting the formation of a moderately random copolymer structure. Thermo‐mechanical analysis shows large concentrations of AMPS had a plasticizing effect on the network structure. Solvent removal using supercritical carbon dioxide and thermal drying were compared, and the drying technique were shown to have an effect on the glass transition temperature (T_g), with the lowest T_g being 146°C for supercritically dried samples and 121°C for thermally dried systems. Gel permeation chromatography shows that there is a significant fraction of an unbound mobile phase within the network structure that might be acting as a plasticizing agent for the copolymer structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polystyrene/attapulgite nanocomposites prepared via in situ suspension polymerization with redox initiation system

A series of polymer–clay nanocomposites consisting of polystyrene (PS) and attapuglite (ATP) were prepared successfully. First, silane coupling agent containing aromatic tertiary amine groups was synthesized to functionalize ATP (M‐ATP). Then, PS nanocomposites with varied clay loadings were prepared via in situ suspension polymerization process with a redox initiation system consisting of aromatic tertiary amine and benzoyl peroxide. The synthesis of silane coupling agent and functionalization of ATP were confirmed by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectra, and X‐ray photoelectron spectroscopy. Mechanical properties, morphology, thermal stability, and rheological behavior of nanocomposites were investigated to illuminate the effects of M‐ATP on the structure and properties of nanocomposites. Field‐emission scanning electron microscope images revealed an ideal dispersion of M‐ATP and an enhanced toughness of nanocomposites. The improved interface interaction between M‐ATP and PS matrix endowed the nanocomposites with outstanding mechanical properties and thermal stability. The formation of hybrid network in the nanocomposites containing 3 wt % M‐ATP resulted in higher complex viscosity (η*), storage modulus (G′), and lower loss factor (tanδ) compared with the pristine PS and PS/ATP nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41567.     

Effect of water‐assisted extrusion and solid‐state polymerization on the microstructure of PET/Clay nanocomposites

An melt‐mixing process has been used to prepare Poly(ethylene terephthalate) (PET)/clay nanocomposites with high degree of clay delamination. In this method, steam was fed into a twin‐screw extruder (TSE) to reduce the PET molecular weight and to facilitate their diffusion into the gallery spacing of organoclays. Subsequently, the molecular weight (M_W) reduction of the PET matrix due to hydrolysis by water was compensated by solid‐state polymerization (SSP). The effect of the thermodynamic compatibility of PET and organoclays on the exfoliated microstructure of the nanocomposites was also examined by using three different nanoclays. The dispersion of Cloisite 30B (C30B) in PET was found to be better than that of Nanomer I.28E (I28E) and Cloisite Na⁺. The effect of feeding rate and consequently residence time on the properties of PET nanocomposites was also investigated. The results reveal more delamination of organoclay platelets in PET‐C30B nanocomposites processed at low feeding rate compared to those processed at high feeding rate. Enhanced mechanical and barrier properties were observed in PET nanocomposites after SSP compared to the nanocomposites prepared by conventional melt‐mixing. POLYM. ENG. SCI., 54:1723–1736, 2014. © 2013 Society of Plastics Engineers     

Preparation and characterization of polyhydroxyurethane/silica nanocomposites via in situ surface‐initiated polymerization

The polyhydroxyurethane/silica nanocomposite (PHU/SN) was prepared by the in situ surface‐initiated polymerization of a five‐membered cyclic carbonate, 2,2‐bis[p‐(1,3‐dioxolan‐2‐one‐4‐yl‐methoxy)phenyl]propane (B5CC) and hexamethylene diamine, from the surfaces of the aminopropyl silica nanoparticles (APSN) for the first time. The percentage of grafting (PG%) and the grafting efficiency (GE%) of 27% and 19% were calculated from the results of thermogravimetric analysis (TGA), respectively, after the free polyhydroxyurethane was washed off. The chemical grafting of the polymer was also confirmed using Fourier transform infrared (FTIR) and the morphology of the silica nanoparticles in the nanocomposite was characterized by transmission electron microscope (TEM). POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

UV‐curing and mechanical properties of polyester–acrylate nanocomposites films with silane‐modified antimony doped tin oxide nanoparticles

Antimony doped tin oxide (ATO) nanoparticles were used as nanofillers to improve mechanical properties of UV‐cured polyester–acrylate films. To improve the dispersion of ATO nanoparticles in the polyester–acrylate resin matrix and to strengthen interfacial interactions between ATO nanoparticles and the resin matrix ATO nanoparticles were first organically modified with 3‐methacryloxypropyltrimethoxysilane (MPS). The modification of ATO nanoparticles with MPS was confirmed by FTIR spectroscopy and thermogravimetric analysis (TGA). UV‐curing behaviors of the nanocomposites films were investigated by FTIR spectroscopy. Compared with the film with neat ATO nanoparticles, the film with the same amount of MPS‐modified ATO nanoparticles showed slightly higher UV‐curing rate and final conversion. The mechanical properties of the nanocomposites films were measured by universal testing machine. The MPS‐modified ATO nanoparticles could improve considerably the mechanical properties of the UV‐cured polyester–acrylate nanocomposites films. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of CTAB‐intercalated graphene/polyaniline nanocomposites via in situ oxidative polymerization

Polyaniline/graphene (PANI/GN) nanocomposites were fabricated via in‐situ oxidative polymerization of aniline in the presence of cetyltrimethylammonium bromide (CTAB) modified graphene (CGN) in 1M hydrochloric acid (HCl) solution. The morphology and structure of PANI/GN samples were investigated by Fourier transform infrared spectrum, X‐ray diffraction, ultraviolet and visible spectrum, thermogravimetric analysis, field‐emission scanning microscope (FE‐SEM), and transmitting electron microscopy (TEM). The conductivities of the PANI/GN nanocomposites were measured using four‐probe electrical conductivity measurement. The results indicated that the GN sheets disperse into the form of monolayer or stack few layers in PANI matrix. The GN sheets serve as a support material for PANI particles and the structure of GN covered with PANI nanoparticles were confirmed by FE‐SEM and TEM. The electrical conductivities of the PANI/GN samples have been improved compared with pure PANI prepared in the similar condition. POLYM. COMPOS., 36:1767–1774, 2015. © 2014 Society of Plastics Engineers     

In situ polymerization of polyamide 66 nanocomposites utilizing interfacial polycondensation. III. Co‐synthesis of silica nanocomposites via sol–gel chemistry

In situ co‐synthesis of nylon 66 (PA66)‐silica nanocomposites can be accomplished through sol–gel chemistry conducted simultaneously with the nylon polymerization. Unfunctionalized silica nanocomposites and bonded silica nanocomposites wherein the inorganic silica phase chemically couples to the nylon polymer through a functionalized silane are generated via the simultaneous initiation of synthesis reactions in the inorganic and organic species. The effects of agitation and water‐to‐silane molar ratio on the courses of the inorganic and organic reactions and the generated silica morphology in the resulting nanocomposites are investigated using the tools of Brookfield Viscometer, Fourier transform infrared spectroscopy, and transmission electron microscopy. Dynamic mechanical analysis confirms the mechanical reinforcement of the various nanocomposites in relation to their silica content and network morphology. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Intercalation structure and toughening mechanism of graphene/urea‐formaldehyde nanocomposites prepared via in situ polymerization

Based on the industrialized graphene (GN) product, a series of graphene/urea‐formaldehyde nanocomposites were synthesized via in situ polymerization by incorporation of silicon coupling agent with terminal amino groups (SA) as the compatibilizer. The results showed that addition of SA coupling agent led to much more efficient grafting of UF molecules on the GN surface with high layer thickness by formation of hydrogen bonding, and thus complete exfoliation and uniform dispersion of GN were achieved for the composites. Compared with neat UF, the addition of 1.0 wt% GN resulted in a roughly 25% increase in tensile strength and 12% increase in impact strength; meanwhile the impact fracture surfaces of the composite showed obvious ductile fracture characteristics, indicating the reinforcing and toughening effect of GN on the UF matrix. With increasing GN content, the storage modulus, glass transition temperature and crosslinking density of UF increased, while the tan δ_max decreased, suggesting that a double crosslinking network structure with GN centered crosslinking point and chemical crosslinking point of UF molecular chains formed, leading to improvement in the stiffness of the composites. The present work showed promising potential for developing high performance UF resin on an industrial scale. © 2017 Society of Chemical Industry     

Phase behavior of a sodium dodecanol allyl sulfosuccinic diester/n‐pentanol/methyl acrylate/butyl acrylate/water microemulsion system and preparation of acrylate latexes by microemulsion polymerization

Pseudoternary phase diagrams of quaternary microemulsion systems composed of the reactive surfactant sodium dodecanol allyl sulfosuccinic diester, n‐pentanol, methyl acrylate/butyl acrylate, and water were made. The influence of the mass ratio of sodium dodecanol allyl sulfosuccinic diester to the cosurfactant (n‐pentanol) in the system and the influence of electrolyte sodium chloride on the microemulsion area were examined. The microstructure of the microemulsion was determined with a conductance technique. The results suggested that there were three structures in the microemulsion system: water in oil, oil in water, and a bicontinuous phase. Microemulsion polymerizations were carried with some point in the microemulsion region being chosen as the formulation. The structure and configuration of the polymer latexes were determined and analyzed with Fourier transform infrared, differential scanning calorimetry, and scanning electron microscopy. The results suggested that the reactive surfactant could participate in the polymerization with the monomers to some extent; the glass‐transition temperature of the latex was ?31.4°C. The polymer latex was transformed gradually from an open porous structure to a closed porous structure when its pregnant microemulsion was varied from a bicontinuous structure to an oil‐in‐water structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of poly(arylene disulfide)–vermiculite nanocomposites via in situ ring‐opening polymerization of macrocyclic oligomers

Exfoliated poly(4, 4′‐oxybis(benzene)disulfide)/vermiculite (POBDS/VMT) nanocomposites were successfully synthesized via in situ melt intercalation of cyclo(4, 4′‐oxybis(benzene)disulfide) oligomers (COBDS) into octadecylammonium‐exchanged VMT (organo‐VMT). The POBDS/VMT nanocomposites were melt fabricated in a two‐step process. First, the COBDS/VMT nanocomposite precursor was fabricated by melt delaminating organo‐VMT with COBDS at a temperature slightly higher than its melting point. Subsequently, exfoliated POBDS‐VMT nanocomposites can be prepared in situ via instant melt ring‐opening polymerization of the COBDS‐VMT nanocomposite precursor. The nanoscale dispersion of VMT layers within POBDS polymer was confirmed by X‐ray diffraction, scanning electron microscopy and transmission electron microscopy. High molecular weight POBDS polymer was formed in a few minutes at the same time as the nanocomposite formation. The results of dynamic mechanical analysis showed that the storage modulus and glass transition temperature of the nanocomposites are much higher than those of the POBDS matrix, even with a very small amount of VMT addition. This methodology provides a potential approach to synthesize high‐performance polymer/clay nanocomposites. Copyright © 2004 Society of Chemical Industry