Use of acrylic based surfmers for the preparation of exfoliated polystyrene–clay nanocomposites

Two polymerizable cationic surfactants, (11-acryloyloxyundecyl)dimethyl(2-hydroxyethyl)ammonium bromide (hydroxyethyl surfmer) and (11-acryloyloxyundecyl)dimethylethylammonium bromide (ethyl surfmer), were used for the modification of montmorillonite (MMT) clay. The modification of MMT dispersions was carried out by ion exchange of the sodium ions in Na⁺-MMT by surfactants in aqueous media. Modified MMT clays were then dispersed in styrene and subsequently polymerized in bulk by a free-radical polymerization reaction to yield polystyrene–clay nanocomposites. An exfoliated structure was obtained using the ethyl surfmer-modified clay, whereas a mixed exfoliated/intercalated structure was obtained using the hydroxyethyl surfmer-modified clay. Nanocomposite structures were confirmed by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The nanocomposites exhibited enhanced thermal stability and an increase in glass transition temperature, relative to neat polystyrene. The nanocomposites also exhibited enhanced mechanical properties, which were dependent on the clay loading. Intercalated polystyrene–clay nanocomposites were obtained using the non-polymerizable surfactant-modified clay (cetyltrimethylammonium bromide). Nanocomposites made from mixtures of surfmer-modified and CTAB-modified clays were also prepared, showing intermediate properties. However, when the nanocomposites were prepared in solution only intercalated morphologies were obtained. This was attributed to the competition between the solvent molecules and monomer in penetrating into clay galleries. These nanocomposites also exhibited enhanced thermal stability relative to the virgin polystyrene prepared by the same method. Similar temperatures of degradation (at 50% decomposition) were found for these nanocomposites relative to those prepared by bulk polymerization.     

Photopolymerization kinetics of poly(acrylate)-clay composites using polymerizable surfactants

Photopolymerization kinetics of polymer-clay nanocomposite systems utilizing polymerizable quaternary ammonium surfactants as dispersants were systematically investigated to determine the effects of surfactant type and clay morphology on polymerization behavior. For these studies, either polymerizable surfactants were mixed into a clay-monomer system or the surfactants were ionically anchored to clay surfaces and added to the monomer for in situ photopolymerization. Higher photopolymerization rates are observed with increasing polymerizable surfactant concentration, while no significant change or decreases in polymerization rate occur with incorporation of non-polymerizable surfactants. The higher rates observed for polymerizable surfactant systems are due to lower apparent termination rate parameters stemming from immobilization of the surfactants. For clay that is modified with ionically bonded quaternary ammonium surfactants, polymerization rates decrease in both polymerizable and non-polymerizable organoclay systems with increasing concentration, but this decrease is much smaller when polymerizable organoclays are utilized. For the same organoclay concentration, higher polymerization rates and double bond conversions result with increasing polymerizable surfactant concentration via cation exchange. Significant increases in polymerization rate also occur with increasing degree of clay exfoliation.     

Preparation and characterization of polystyrene–clay nanocomposites by free‐radical polymerization

The polymerizable cationic surfactant, vinylbenzyldimethylethanolammouium chloride (VBDEAC), was synthesized to functionalize montmorillonite (MMT) clay and used to prepare exfoliated polystyrene–clay nanocomposites. The organophilic MMT was prepared by Na⁺ exchanged montmorillonite and ammonium cations of the VBDEAC in an aqueous medium. Polystyrene–clay nanocomposites were prepared by free‐radical polymerization of the styrene containing intercalated organophilic MMT. Dispersion of the intercalated montmorillonite in the polystyrene matrix determined by X‐ray diffraction reveals that the basal spacing is higher than 17.6 nm. These nanocomposites were characterized by differential scanning calorimetry (DSC), transmission electron micrograph (TEM), thermal gravimetric analysis (TGA), and mechanical properties. The exfoliated nanocomposites have higher thermal stability and better mechanical properties than the pure polystyrene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1370–1377, 2002     

The effect of surface chemistry and nanoclay loading on the microcellular structure of porous poly(d,l lactic acid) nanocomposites

Three series of polymer nanocomposites, based on poly(d,l lactic acid) (PDLLA) and organically modified montmorillonite, were prepared by the melt and the solution intercalation technique. The first series was prepared by extrusion using different clay loadings. The second series of nanohybrids was obtained using montmorillonite modified with different types of alkylammonium surfactants in terms of carbon-chain lengths (i.e., 4, 8, 12, 16 and 18). In the third series of nanocomposites, the organic cation concentration of the surfactant was varying. Microcellular porous materials were, afterwards, fabricated from these three series of nanocomposites. The porous structures of pure and nanocomposite PDLLA were prepared by isothermal pressure quench using supercritical CO₂ as foaming agent. The morphology of the produced porous materials was investigated by scanning electron microscopy (SEM). Image processing of the samples revealed that the final cellular structure is strongly related to clay loading and, both, the type and the organic cation concentration of the alkylammonium used for the modification of the clay. The results suggest that the size of the pores decreases and the cell density and bulk foam density increase with the increase of clay loading or the surfactant's carbon chain length or the cation concentration in clay. Clay dispersion seems to be enhanced by the supercritical treatment upon foaming.     

Novel Maleate Surfmer for Stabilization High-solid Content of Methyl Methacrylate/Butyl Acrylate Copolymer Emulsion System

A novel polymerizable surfactant (surfmer) based on nonyl phenol ethoxylate backbone and maleic anhydride was synthesized. The chemical structure of the surfmer was characterized by ¹³C, ¹H nuclear magnetic resonance, and surface tension analyses. The surfmer was used in emulsion system of methyl methacrylate/butyl acrylate copolymer at different concentrations to explore its stabilization efficiency using seed emulsion polymerization technique. The result of thermogravimetric analysis showed that the incorporation of the surfmer retarded the decomposing of the polymer chain. The stability of the emulsion was enhanced by adding the surfmer, but the glass transition of the film was decreased dramatically.     

Improving Gas Sequestration by Surfactant‐Alternating‐Gas Injection: A Comparative Evaluation of the Surfactant Type and Concentration

Gas injection into porous subsurface geological formations for geological storage is currently considered the most preferable and practicable means of reducing greenhouse gases due to the huge capacity of deep saline aquifers. Residual trapping of gas plays an important role in immobilization of injected gas into an aquifer. Surfactant‐alternating‐gas (SAG) injection can be used as a mobility control method in gas sequestration and several simulation studies explained different aspects of residual‐gas trapping. However, research in this field is inconclusive and needs more attention to develop a better understanding. In this work, we used 3 different surfactants from different classes at various concentrations to assess gas‐sequestration efficiency using SAG methods in carbonate and sandstone rocks. This work is the first of its kind on the comparative performance of different surfactants for gas sequestration in different rocks. The surfactants were hydrocarbon zwitterionic, fluorinated zwitterionic, and nonionic. It was found that residual‐gas saturation increases by increasing the surfactant concentration. The increase in residual trapping with surfactant concentration also depends on the type of surfactant and rock. In both rock types considered, the best performance was achieved using fluorinated zwitterionic surfactants followed by hydrocarbon zwitterionic surfactants. In addition, a synergetic effect between hydrocarbon and fluorinated surfactants further improves the residual‐gas saturation. The residual‐gas trapping was higher in the tight sample compared to highly permeable samples. This will help in developing an understanding of surfactant optimization and selection for gas sequestration using the SAG method.     

The application research of environment-friendly reactive surfactants in acrylate emulsion pressure sensitive adhesives

In this article acrylate pressure sensitive adhesive (PSA) latexes were synthesized via a pre-emulsion seeded semi-batch emulsion polymerization process with a conventional nonreactive surfactant (CO-436) and two polymerizable surfactants (traditional surfmer SE-10N and environment-friendly surfmer SR-10). The effects of surfactant contents on the particle size, zeta potential, electrolyte stability of the latexes and gel content, sol molecular weight (M_w, M_n), water absorption of the PSA copolymers were investigated. In addition, X-ray photoelectron spectroscopy (XPS) and contact angle measurements were used to characterize the latex films. The results showed that the particle sizes of latexes prepared with surfmers were smaller than their CO-436 containing counterparts. And the latexes prepared with surfmers had a lower storage stability than the one prepared with CO-436. However, surfmers can improve the electrolyte stability of the latex. Furthermore, the water resistances of the latexes prepared with surfmers were better than that of the latex with CO-436, which can be confirmed by water absorption, contact angle and XPS analysis. The results also indicated that the PSA prepared with SR-10 exhibited the highest gel content among the three surfactants. Finally, the effects of surfactants on the adhesive properties of the PSAs were also evaluated.     

Synthesis of unsaturated polyester‐clay nanocomposites using reactive organoclays

Two polymerizable cationic surfactants, vinylbenzyl n‐alkyldimethyl (n = 12 or 18) ammonium chlorides, were used for functionalization of montmorillonite (MMT) and preparation of unsaturated polyester (UP)‐clay nanocomposites. Polymerizable organophilic clays were prepared by exchanging the sodium ions of MMT with vinylbenzyldodecyldimethyl ammonium chloride (VDAC) or vinylbenzyloctadecyldimethyl ammonium chloride (VOAC) in an aqueous medium. The dispersion of organoclays in UP led to gel formation. UP/VDAC‐MMT resulted in intercalated nanocomposites while UP/VOAC‐MMT formed partially exfoliated nanocomposites. The nanocomposites exhibited higher dynamic modulus than pristine UP.     

Synthesis of a novel polymerizable surfactant and its application in the emulsion polymerization of vinyl acetate,butyl acrylate,Veova 10, and hexafluorobutyl methacrylate

A novel anionic, polymerizable fumaric surfactant (surfmer) was synthesized. The chemical structure of the surfactant was confirmed with ¹H‐NMR, IR, and mass spectrometry. The surfmer was then used with constant addition profiles in the semicontinuous polymerization of vinyl acetate, butyl acrylate, Veova 10, and hexafluorobutyl methacrylate. The particle size, amount of coagulum, and stability against electrolytes and freezing/thawing were evaluated. Films were cast from latices; then, photographs were taken of the films after immersion in water for days, and the water adsorption was assessed. As a reference, an unreactive surfactant (sodium dodecyl sulfate) was also used for the polymerization. Compared with sodium dodecyl sulfate, the surfmer behaved much better with respect to the stability of the latices and the water sensitivity of the films. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structural Effects of Nonionic Surfactants on Their Ability to Reduce the Dissolution Pressures of Heavy Hydrocarbons in Supercritical CO2

The effects of selected nonionic surfactants on dissolution pressures of the octacosane and hydrocarbon mixtures in supercritical CO₂ (scCO₂) were investigated at 318–343 K to study relationships between the structures of the surfactants and their ability to improve solubility. Dissolution pressures of the solutes were experimentally observed to be decreased by at most 11.10% and at least 0.44% in the presence of the surfactants. However, this solubility‐improving performance was diminished with an increase in the molecular chain length of the surfactant. Linear surfactants gave better solubility‐improving performances in the octacosane/scCO₂ systems, while branched compounds were better in the hydrocarbon mixture/scCO₂ systems, which are attributed to the similarity of the chain length between the surfactant and the solute. X‐ray computed tomography tests provided evidence for direct material exchange between the hydrocarbon mixture and scCO₂.     

一种富马酸类可聚合乳化剂的合成及其乳液性能研究

马来酸酐和十四醇在80℃酯化反应1 h得马来酸单十四酯;然后和PCl3在60℃反应2 h得单十四酯马来酰氯;最后与N-甲基牛磺酸钠在70℃反应1 h得白色粉末状固体,用w(CH3CH2OH)=95%的乙醇重结晶,得到一种富马酸类磺酸盐阴离子可聚合乳化剂——N-甲基-N-十四醇单酯马来酰基-牛磺酸钠。用质谱和1HNMR鉴定了目标化合物,结构正确。将所合成的可聚合乳化剂用于醋酸乙烯酯-丙烯酸丁酯-叔碳酸乙烯酯-甲基丙烯酸六氟丁酯乳液聚合,单体转化率97.75%,凝胶率0.02%,乳液固体份质量分数43.52%,乳液多分散性系数(PDI)0.02,呈单分散性。作为对比,非可聚合阴离子乳化剂十二烷基硫酸钠(SDS)同样应用到该乳液聚合体系中,结果发现:由可聚合乳化剂制得的乳液,在耐电解质性能和贮存稳定性方面有所提高,在成膜耐水性方面,可聚合乳化剂制得的乳胶膜浸入水中30 d后,吸水率为13.70%,SDS的吸水率是103.09%,是前者的7.52倍,可聚合乳化剂很好地提高了乳液成膜后的耐水性。     

Polycarbonate nanocomposites: Part 2. Degradation and color formation

Polycarbonate nanocomposites were prepared using two different twin screw extruders from a series of organoclays based on sodium montmorillonite, with somewhat high iron content, exchanged with various amine surfactants. It seems that a longer residence time and/or broader residence time distribution are more effective for dispersing the organoclay. The effects of organoclay structure on color formation during melt processing were quantified using colorimeter and UV-Vis spectroscopy techniques. Color formation in the PC nanocomposites depends on the type of organoclay and the type of pristine clay employed. Double bonds in the hydrocarbon tail of the surfactants lead to more darkly colored materials than saturated surfactants. The most severe color was observed when using a surfactant containing hydroxy-ethyl groups and a hydrocarbon tail derived from tallow. Molecular weight degradation of the PC matrix during melt processing produces phenolic end groups which were tracked by UV-Vis spectroscopy. Greater dispersion of the clay generally led to higher reduction in molecular weight due to the increased surface area of clay exposed; however, for color, the situation is far more complex. Hydroxy-ethyl groups and tallow unit on the surfactant lead to more degradation. A selected series of organoclays based on synthetic clay Laponite^® and calcium montmorillonite from Texas (TX-MMT) were also prepared to explore the effects of the clay structure. Laponite^® and TX-MMT produce less color formation in PC nanocomposites than montmorillonite probably due to lower content of iron. Dynamic rheological properties support the trends of molecular weight degradation and dispersion of clay.     

The role of polymerizable organophilic clay during preparing polyethylene nanocomposite via filling polymerization

Effect of polymerizable montmorillonites (P‐MMTs) on the morphology of polyethylene/montmorillonites (PE/MMTs) nanocomposites during filling polymerization was studied. The microstructure analysis showed that the P‐MMTs were more exfoliatable than nonpolymerizable MMTs in the preparation of PE/MMTs nanocomposites. By examining the influence of the polymerization condition on the microstructure of the resultant nanocomposites, it was confirmed that the shear force formed by the mechanical stirring was the driving force of the exfoliation dispersion of MMT sheets during the filling polymerization. Comparatively, the shear force on MMT sheets might be increased due to strong interaction between PE chains linked to the surface of P‐MMTs and the solvents molecules, which is the reason that polymerizable clay is more exfoliatable than nonpolymerizable clay. The copolymerization between polymerizable modifier and ethylene was confirmed by NMR measurements. Furthermore, the morphology of the resultant nanocomposites was influenced by the concentration of the dispersed P‐MMTs. The degree of exfoliation of the resultant nanocomposites at a relatively low concentration was higher than that at a high concentration. This is because of the multiscale organization of the organoclay dispersed in the organic medium. High exfoliation degree of MMTs and improved interaction between PE matrix and P‐MMTs in PE/P‐MMTs nanocomposites led to significant improvements in mechanical properties and barrier properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A study of the effect of surfactants on the properties of polystyrene‐montmorillonite nanocomposites

Polystyrene‐Organo Montmorillonite (PS‐MMT) nanocomposites were prepared by suspension free radical polymerization of styrene in the dispersed organophilic montmorillonite. The results of X‐ray diffraction (XRD) and Transmission Electron Microscopy (TEM) indicated that exfoliated nanocomposites were achieved. The effect of organic modifiers (surfactants) on the properties of the synthesized nanocomposites was studied. It is found that polystyrene‐MMT nanocomposite with 5.0 wt% of organo‐MMT gave the greatest improvement in thermal stability, and polystyrene‐MMT nanocomposites with 7.5 wt% of organo‐MMT showed the greatest improvement in mechanical properties, compared with that of pure polystyrene (PS) in our experimental conditions. The alkyl chain length of surfactant used in fabricating organo‐MMT affects the synthesized PS nanocomposites: the longer the alkyl chain length that the surfactant possesses, the higher the glass transition temperature of the PS nanocomposite, However, the organoclay in the nanocomposites seems to play a dual role: (a) as nanofiller leading to the increase of storage modulus and (b) as plasticizer leading to the decrease of storage modulus. This results in a lower storage modulus of PS‐TMOMMT and PS‐TMTMMT nanocomposites than that of PS‐TMDMMT and PS‐TMCMMT nanocomposites. Further study is needed to confirm the above hypothesis.     

An Analytically Defined Fire‐Suppressing Foam Formulation for Evaluation of Fluorosurfactant Replacement

A 4‐component, analytically defined, reference fluorosurfactant formulation (Ref‐aqueous film forming foam [AFFF]) composed of 0.3% fluorocarbon‐surfactant concentrate (Capstone 1157), 0.2% hydrocarbon‐surfactant concentrate (Glucopon 215 UP), and 0.5% diethylene glycol mono butyl ether by volume in distilled water was found to have rapid fire extinction comparable to a commercial AFFF in tests conducted on a bench scale and a large scale (28 ft², part of US Military Specification, MIL‐F‐24385F). The Ref‐AFFF was analytically characterized to provide the identity and quantity of the chemical structures of the surfactant molecules that were lacking for commercial AFFF formulations. To arrive at an acceptable Ref‐AFFF formulation, 3 candidate formulations containing different hydrocarbon surfactants in varying amounts were evaluated and ranked relative to a commercial AFFF using a bench‐scale fire‐extinction apparatus; varying the hydrocarbon surfactant was found to affect the fire‐extinction time. The ranking was confirmed by the large‐scale tests suggesting that the bench‐scale apparatus is a reasonable research tool for identifying surfactants likely to succeed in the large‐scale test. In the future, replacing the fluorocarbon surfactant with an alternative surfactant in the Ref‐AFFF enables a direct comparison of fire extinction and environmental impact to identify an acceptable fluorine‐free formulation.     

Phosphonium‐based layered silicate—Poly(ethylene terephthalate) nanocomposites: Stability,thermal and mechanical properties

PET‐clay nanocomposites were prepared using alkyl quaternary ammonium and phosphonium modified clays by melt‐mixing at 280°C using a micro twin screw extruder. The latter clays were prepared by synthesizing phosphonium surfactants using a simple one‐step method followed by a cation exchange reaction. The onset temperature of decomposition (T_onset) for phosphonium clays (>300°C) was found to be significantly higher than that of ammonium clays (around 240°C). The clay modified with a lower concentration (0.8 meq) of phosphonium surfactant showed a higher T_onset as compared to the clay modified with a higher concentration (1.5 meq) of surfactants. Nanocomposites prepared with octadecyltriphenyl phosphonium (C18P) modified clay showed a higher extent of polymer intercalation as compared with benzyltriphenylphosphonium (BTP) and dodecyltriphenylphosphonium (C12P) modified clays. The nanocomposites prepared with ammonium clays showed a significant decrease in the molecular weight of PET during processing due to thermal degradation of ammonium surfactants. This resulted in a substantial decrease in the mechanical properties. The molecular weight of PET was not considerably reduced during processing upon addition of phosphonium clay. The nanocomposites prepared using phosphonium clays showed an improvement in thermal properties as compared with ammonium clay‐based nanocomposites. T_onset increased significantly in the phosphonium clay‐based nanocomposites and was higher for nanocomposites which contained clay modified with lower amount of surfactant. The tensile strength decreased slightly; however, the modulus showed a significant improvement upon addition of phosphonium clays, as compared with PET. Elongation at break decreased sharply with clay. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Adsorptive polyHIPE composites based on biosorbent immobilized nanoclay: Effects of immobilization techniques

Styrene/divinyl benzene‐based macroporous polyHIPE composites were prepared from water‐in‐oil (w/o) high internal phase emulsion (HIPE) templates by using both organo‐modified montmorillonite (MMT) and a nonionic surfactant. For this purpose, Spirulina (Sp) microalgae was immobilized onto Na‐MMT clay by using two different modification techniques. They are based on conventional adsorption in solution (SOL) and novel cryoscopic expansion (C‐XP) assisted adsorption. Highly porous nanocomposites were prepared by using different percentages of modified nanoclays (SpSOLM/SpXPM) with a constant internal phase volume of 80%. The emulsion stability, morphology, and dye adsorption capacities were discussed by paying attention to nanoclay immobilization techniques, clay loading degree and surfactant concentration. The critical amount of nonionic surfactant for formation of the stable neat HIPE template was found to be only 5 vol% with respect to volume of organic phase. However, this amount was further reduced to much less value (2 vol%) with Sp immobilized nanoclays via help of cooperative interactions of Sp and MMT nanoclay. The C‐XP assisted modification of clay led to nanocomposites with 580% higher adsorption capacity for cationic dye. This remarkable benefit was obtained with even 0.5% clay loading and only 2% surfactant concentration. POLYM. ENG. SCI., 58:1229–1240, 2018. © 2017 Society of Plastics Engineers     

Radiation-induced admicellar polymerization of isoprene on silica: Effects of surfactant's chain length

This research compared radiation-induced admicellar polymerization with the traditional thermal process and studied the influence of the hydrocarbon chain length of different surfactants on film formation. Three types of surfactants were used in this study: dodecyl trimethyl ammonium bromide (DTAB), tetradecyl trimethyl ammonium bromide (TTAB) and cetyl trimethyl ammonium bromide (CTAB). Isoprene was used as a monomer for the formation of thin film inside the surfactant bilayers, called admicelle, adsorbed on silica surface. The results showed that an optimum dose can lead to a better film formation on silica, compared with the thermal method. However, when the dose was over the optimum value, the formation of polyisoprene film was diminished. The formation of polyisoprene film was found to depend not only on the hydrocarbon chain length of the surfactant, but also on the density of adsorbed surfactant on silica surface.     

特种表面活性剂和功能性表面活性剂(ⅩⅩ)——含氟双子表面活性剂的合成

按照结构特点对阳离子型、阴离子型、两性离子型和非离子型含氟双子表面活性剂的合成方法和合成路线进行了归纳。含氟双子表面活性剂是一种特殊表面活性剂,氟原子取代了表面活性剂碳氢链中的氢原子,而使其具有更高的表面活性。展望了含氟双子表面活性剂的发展前景。     

Fluorinated acrylic polymers: Surface properties and XPS investigations

A series of polymers based on methylmethacrylate, butylacrylate, and ω‐perfluorooctylalkylacrylate were prepared by radical polymerization. By changing both the length of the hydrocarbon spacer, between the fluorinated chain and the ester function of the fluorinated monomer, and its concentration, the surface properties of the resulting terpolymers were greatly influenced. Polymers containing small amounts of fluorinated comonomer units had considerably reduced surface energies compared to the copolymer poly (methylmethacrylate‐co‐butylacrylate) taken as reference. The outermost surface composition has been investigated by the XPS technique, confirming the strong fluorine enrichment. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 821–827, 2006