Silicone Surfactants Research Articles

GDCh-Intensive Course Surfactants: Detergents, Cosmetics, Technical Applications

For many years the training programme of the German Chemical Society GDCh did not contain a training course on surfactants although both production and use of surfactants play a major role in Germany and interest was there from diverse sides. The sector group “Detergents” (Fachgruppe Waschmittelchemie) of GDCh was recently asked to provide such a course. After setting up a one-day course in Idstein under guidance of Professor Dr. Thomas Knepper and with contributions from experts from the Fachgruppe Waschmittelchemie in 2009 and 2010, the high interest in this event allowed the GDCh to establish a more intense two day course which covers the full spectrum of surfactant technologies including the Personal Care area. This was realised in September 2010 in Essen in the premises of Evonik Goldschmidt GmbH with a broad participation of leading scientists from surfactant research and specialists from the organising company. The participation in this course was again excellent. The participants from Germany and Switzerland came from diverse companies who produce or use surfactants. On day 1, after the welcoming words of Dr. Stefan Silber, Head of the Innovation Management and R & D of Evonik’s Business Unit Consumer Specialties and Dr. Felix M ller, Evonik Goldschmidt GmbH as the organizer of the training course, Professor Dr. Heinz Rehage from Technical University Dortmund started with the general introduction on surfactants and adressed phenomena like micells, CMC and did progress very quickly into the details of modern rheology and the options to study surfactant behaviour in detail making vesicles and liposomes visible and understandable. He went into video-enhanced contrast microscopy, NMR-spectroscopy and isothermal titration calometry as means to visualize surfactant properties. Prof. Dr. Cosima Stubenrauch from Stuttgart University continued with a detailed introduction into the secrets of emulsions and microemulsions, their applications and analytics. She addressed stability issues of emulsions as well as modern technologies like PIT emulsions and went thoroughly through the unique world of microemulsions and their special features. The stability of microemulsions was explained and their special phase diagrams. The third presentation was given by Dr. Peter Schmiedel from Henkel KGaA, who described in depth the current composition of the diverse laundry detergent products on the market, from European powder liquid systems to fabric softeners and special detergents for wool, black fabrics etc. He detailed the mechanisms of bleaching and dye transfer inhibition. He explained as well the actions and synergisms of various ingredients and gave an outlook for the further development of the laundry detergents in different parts of the world. Professor Dr. Thomas Knepper from Fresenius University in Idstein gave his insights into the special problems of surfactant analytics and explained the special environmental background of the fate of surfactants that will be usually intentionally released into wastewater and explained with examples from the Philippines what consequences the use of nonbiodegradable surfactants has for ground water pollution. He focussed as well especially on fluorinated surfactants and the approaches to avoid the bioaccumulation of these materials. Dr. Bernd Glassl from Industrieverband Kosmetik und Waschmittel (IKW, German industry group cosmetics and detergents) in Frankfurt gave finally on the first day an introduction into the special legal situation of surfactants in laundry and cosmetics, a field where European and German law contributes to a lot of details to observe when formulating products. He explained the different biodegradation test protocols and their respective use in different directives. The discussion of the contributions added value for the participants as fairly detailed questions and problems were well solved and addressed by the presenters. On the second day, it was Dr. Joachim Venzmer of Evonik Goldschmidt GmbH, Essen, who started with a presentation on silicone surfactants. He addressed properties and technical applications of this interesting surfactant class far beyond what is found in text books and explained state of art superspreading technology for agricultural applications as well as wetting and release coating, paint wetting and spreading of cosmetic oil explained some of the unique features of silicone surfactants. Dr. Sascha Herrwerth of Evonik Goldschmidt GmbH continued with a presentation on Rinse-Off cosmetic for hairand body cleansing, detailing formulas and explaining effects and properties which are under demand by consumers like foaming, mildness, conditioning and the demands which arise from new ingredients in Personal Care formulations. A special focus was on conditioning agents for shampoos as well as conditioning rinses to be used after washing the hair. The proper viscosity control was addressed as well and how to avoid the problems for rinse-off products at elevated temperatures (the sport-bag-effect). CONFERENCE AND MEETING REPORT

Effect of surfactant and oil additions in the biodegradation of hexane and toluene vapours in batch tests

The biological treatment of gaseous emissions of hydrophobic volatile organic compounds (VOCs) results in low rates of elimination partially because of the low solubility of VOCs in water. Recently, the use of two‐phase partition bioreactors (TPPBs) was proposed to increase the bioavailability and consequently the elimination capacities of this kind of VOC. In the present study, TPPBs operating in a batch feed mode were tested for biodegradation of hexane and toluene vapours with a microbial consortium. The results obtained were compared with single‐phase systems (control experiments). The liquid phase used was silicone oil (organic phase) with the surfactant Pluronic F‐68. Experiments were named F1 and F2 for one and two phases, respectively, and F1S and F2S when the surfactant was included. The maximum specific rates (Srates) of hydrocarbon consumption for hexane and toluene were 539 and 773 mghydrocarbon/(gprotein·h), respectively. For both substrates, the systems that showed the highest Srates of hydrocarbon consumption were F2 and F2S. In experiment F1S the surfactant Pluronic F‐68 increased the solubility of hydrocarbons in the liquid phase, but did not increase the Srates. The maximum percentages of mineralization were 51% and 72% for hexane and toluene, respectively. The results showed that simultaneous addition of silicone oil and surfactant favours the mineralization, but not the rate of biodegradation, of toluene and hexane vapours.

Water-dispersible carbon nanotubes from a mixture of an ethoxy-modified trisiloxane and pluronic block copolymer F127

The ability of a mixture of an ethoxy-modified trisiloxane (a silicone surfactant, named Ag-64) and a block copolymer F127 to disperse carbon nanotubes (CNTs) was investigated by experimental investigation and molecular dynamics simulation. Dispersions with large amounts of individual CNTs were obtained. The quantity of dispersed CNTs was obviously larger than each quantity of the dispersions with individual surfactants at the same concentration, even exceeded the sum of them. The mechanism of dispersing CNTs was also discussed. It can be inferred that Ag-64 and few F127 could wrap onto the surface of CNTs to dispart clusters to individuals, and the other F127 interact with adsorbed Ag-64 and F127 to generate stronger steric stabilization. Thus, a synergistic effect on dispersing CNTs by the mixture of Ag-64 and F127 was observed.

Surface and Friction Behavior of a Silicone Surfactant Adsorbed on Model Textiles Substrates

This study reports on interactions of an amphiphilic block copolymer of polyalkylene oxide-modified poly(dimethylsiloxane) with thin films of polypropylene (PP), polyethylene terephthalate (PET), and nylon, as well as with reference hydrophilic silica surfaces. The dynamics of adsorption, adsorbed mass, and viscoelasticity of the adsorbed layer are quantified by using a quartz crystal microbalance, while boundary layer lubrication behaviors are studied by using lateral force microscopy. Driven by hydrophobic interactions, the silicone surfactant adsorbs following a Langmuir isotherm and forms strongly adsorbed layers on the polymer surfaces with an areal mass directly related to the hydrophobicity of the substrate. The self-assembled silicone surfactant molecules improve significantly wettability and lower friction. The results reported herein will broaden our understanding of lubrication phenomena in textile and fiber processing applications.

The Synthesis and Characterization of Polyether-Modified Polysiloxane Phosphate

In order to combine the properties of phosphate surfactants and silicone surfactants, the polyether-modified polysiloxane phosphate (PPSP) was prepared. Firstly, the intermediate was synthesized through the hydrosilylation of hydricpolysiloxane and alkyl polyether. Then the polyether-modified polysiloxane phosphate was prepared through the phosphorylation reaction of intermediate and P2O5. The optimum condition of the phosphorylation reaction was the reaction temperature was 80°C, reaction time was 3.5h and molar ratio of -OH: P2O5 was 3.0:1.0. The molecular structure of phosphate was characterized by FTIR and 31P-NMR. The components and their capabilities were also studied. The CMC of PPSP was 0.58g/L and the surface tension related was 25.78mN/m, but the foaming power of PPSP is relatively low.

The use of surfactants to enhance acaricide control of Phytonemus pallidus (Acari: Tarsonemidae) in strawberry

The tarsonemid mite, Phytonemus ( Tarsonemus) pallidus ssp. fragariae (Zimmerman), is a serious pest of strawberry throughout much of Europe and North America. Many of the plant protection products previously effective against the mite, which causes stunting and distorting of leaves and buds, reducing fruit yield and quality, are no longer available. Finding alternative acaricides for control is a priority. In two field trials, we tested 9 foliar applied plant protection products to determine the efficacy for control of Phytonemus pallidus, and to assess their effects on natural enemies. The products tested as foliar applications (dose ha −1) were; abamectin 18 g/l EC (250, 500, 750, 1250 ml), tebufenpyrad 20% WP (500 g), fenpyroximate 51.3 g/l SC (1.0 l), bifenazate > 90% WP (400 ml), spiromesifen 24 g/l SC (500 ml), acequinocyl 15.8% SC (1.0 l), spirodiclofen 240 g/l SC (400 ml), etoxazole 110 g/l SC, and the surfactant, Silwett L-77 (Heptamethyltrisiloxane 0.05% (50 ml)). Effective products were used in admixture with the surfactant to investigate potential increased efficiency against P. pallidus. In each experiment, two applications were applied to plants previously inoculated with P. pallidus. None of the products controlled the mite effectively when applied alone, but the addition of Silwett L-77 greatly improved control of the pest, particularly in combination with abamectin, etoxazole and tebufenpyrad. These treatments reduced P. pallidus mite numbers by 98, 85 and 80%, respectively. Many of the acaricidal products that are normally active against other species of Acari probably fail to control P. pallidus because of the inaccessibility of the mite within the fold of the young leaflets. In addition, the leaves of strawberry plants are more waxy and hairy than most other crops and are difficult to wet. Hence, significant improvement in efficacy of some products can be achieved if mixed with the silicone surfactant.

Effect of adjuvants on the rainfastness and performance of tribenuron‐methyl on broad‐leaved weeds

The influence of a non‐ionic surfactant (20% isodecyl alcohol ethoxylate plus 0.7% silicone surfactants), an anionic surfactant (25.5% alkylethersulfate sodium salt), and a vegetable oil (95% natural rapeseed oil with 5% compound emulsifiers) on the performance and rainfastness of a new commercial formulation of tribenuron‐methyl was assessed on four broad‐leaved weeds: wild mustard (Sinapis arvensis), scentless mayweed (Tripleurospermum inodorum), common poppy (Papaver rhoeas), and common lambsquarters (Chenopodium album). In one experiment, six doses of tribenuron‐methyl alone or in a mixture with each of the three adjuvants were applied to each weed species at two different leaf stages. In another experiment, the plants of T. inodorum were sprayed and subsequently subjected to 3 mm of rain at 1, 2, and 4 h after treatment (HAT). The activity of tribenuron‐methyl was significantly enhanced by all the adjuvants on all the weed species and only minor differences were observed among the tested adjuvants. The impact of the adjuvants varied among the weed species and growth stages. The highest response to the inclusion of adjuvants in the spray liquid was found at the late growth stage and on C. album, followed by P. rhoeas and T. inodorum, while S. arvensis was less responsive to the adjuvants. All the adjuvants significantly improved the rainfastness of tribenuron‐methyl on T. inodorum, with differences among the adjuvants being more pronounced when rain occurred shortly after herbicide application. The effect of the vegetable oil on tribenuron‐methyl's rainfastness was significantly lower than that of the surfactants with rain at 1 HAT, while no significant differences among the three adjuvants were observed when rain occurred at 2 and 4 HAT.

반경질 폴리우레탄 발포체의 물성에 대한 사슬 연장제와 무기 충전제의 영향

The physical properties of polymeric foams depend on the density of foams, physical properties of base polymers, the content of open cells, and cell structures including the size and its distribution, the shape of cell, and the thickness of skin layer. The foam density is affected by the chemistry of raw materials, the concentration of crosslinking agent and the blowing agent as well as the operating parameters during production process. In this study, the basic formulations of foams are composed of polyester polyol, MDI, amine catalyst, tin catalyst, silicone surfactant, and water. Cross-linking density of polyurethane was increased by using chain extenders. Also, the mechanical properties of polyurethane foam were improved by using the inorganic fillers (silica 1,2 and talc 1,2) having different contents and particle sizes. We investigated the properties of modulus, tensile strength, compressive strength and hardness of foams obtained by changing kind of inorganic filler and chain extender, and observed the distribution of inorganic filler as well as variation of cell size within the foams by electron microscopy.

Silicone foams stabilized by surfactants generated in situ from allyl-functionalized PEG

Silicone foams normally require the use of agents or chemical reactions that blow gases, and a surfactant for bubble stabilization. We have discovered that the presence of monoallyl-functionalized poly(ethylene glycol) (PEG) leads to large increases in the viscosity of silicone pre-elastomers such that stable foams form with bubbles mostly being generated by coalescence of dissolved gases during the normal degassing process. Although silicone elastomer cure may take up to 24 h for completion, the foams remain stable during this time when appropriate concentrations of allyl-PEG and curing catalyst are used. No traditional surfactant is required, but PEG-modified silicone surfactants are formed in situ by covalent grafting of the PEG to the silicone matrix, leading to the increase in viscosity. The presence of allyl-PEG decreases elastomer cure efficiency, but this is readily overcome, if necessary, to generate more rigid foams by the use of additional platinum catalyst, in which case foaming occurs both due to loss of dissolved gases and to hydrogen evolution. Foam stabilization with appropriate allyl-PEG compounds is a consequence of an initial viscosity increase.

Effects of adjuvant and conidial concentration on the efficacy of Beauveria bassiana for the control of the two spotted spider mite, Tetranychus urticae

Greenhouse experiments were conducted on various crops (cucumber, tomato, eggplant, green bean) to ascertain the effects of Break-thru (polyether-polymethylsiloxane-copolymer, a silicone surfactant) and an oil emulsion, on Beauveria bassiana (Balsamo) Vuillemin (Bb) applications for the control of the two spotted spider mite, Tetranychus urticae Koch. The objectives were to compare a) the efficacy of Bb control when applied in aqueous Break-thru or an oil emulsion; b) the effects of various concentrations of Bb conidia, as affected by each surfactant; and c) the effects of Break-thru on the activity of the fungus. Conidia were suspended either in an aqueous Break-thru or an emulsifiable formulation at different conidial concentrations (1.05 x 10(6), 2.1 x 10(6) and 4.2 x 10(6) conidia ml(-1)) and sprayed onto leaves 2 weeks after artificial pest inoculation. Two sprays were performed, with an interval of one week from one spray to another, and T. urticae population counts (both motile and egg stages) were made on plant leaves 7 days after each spray. Bb conidia in Break-thru((R)) were more efficacious than conidia in emulsifiable formulation. With the highest rate of conidia (4.2 x 10(6) conidia ml(-1)), mortality of adult mites ranged from 60 +/- 4.2 (mean +/- SE) to 85.7 +/- 4.3% in the Break-thru suspension and 39.4 +/- 7 to 61.3 +/- 6% in the oil emulsion. Leaf damage index was also substantially reduced from 70% in the unsprayed control to 40% by the application of Bb conidia at the highest rate with Break-thru. Break-thru can be combined with Bb in the integrated management of T. urticae and Isolate R444 is a promising candidate for the control of the pest.

Dispersing carbon nanotubes in aqueous solutions by a silicon surfactant: Experimental and molecular dynamics simulation study

The dispersion effect of carbon nanotubes (CNTs) in aqueous solutions by a silicon surfactant (ethoxy modified trisiloxane, named Ag-64) was investigated in detail using experimental method and molecular dynamics simulation. The Si–O–Si chain of silicon surfactant was flexible due to long Si–C bond and it could easily wrap onto the surface of CNTs through hydrophobic and other intermolecular interactions. The hydrophilic part of PEO provided the CNTs dispersed in the aqueous solution and prevented CNTs from aggregating in water through steric stabilization. It was found that Ag-64 could disperse CNTs with different diameters and it was an effective dispersing agent. The results of molecular dynamics simulation indicated that Ag-64 molecules could wrap onto the surface of CNTs leading to steric stabilization so that it could well disperse CNTs, and Van der Waals attraction was the dominating force of Ag-64 adsorbing onto CNTs. Our study may provide experimental and theoretical basis for using silicon surfactants to disperse CNTs, which can open the avenue of new applications for silicon surfactants.

Effect of the addition of wood flours on the properties of rigid polyurethane foam

AbstractThe objective of this study is to investigate an appropriate process to fabricate the wood‐polyurethane hybrid composites [wood‐polyurethane foam (PUF)]. Rigid PUFs that contain up to 20% wood flours were successfully fabricated from polymeric 4,4‐diphenylmethane diisocyanate, polyols, silicone surfactant, dibutin dilaurate/dimethylethanolamine catalysts, and distilled water (chemical blowing agent). The effects of hydroxyl value of polyols, wood flour particle size, wood flour content, isocyanate index, and water amount on the compressive property of foam were investigated. The morphology of the cell was observed with a scanning electron microscope. Wood‐PUF with different densities were prepared at different water contents in the wood flours. The relationship between the compressive property and density was established following the Power law. The incorporation of wood flour improved the compressive property of PUF, whereas its tensile and flexural properties were reduced. The thermal stability of the PUF was improved with the addition of wood flour. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Exfoliation of Clays in Poly(dimethylsiloxane) Rubber Using an Unexpected Couple: A Silicone Surfactant and Water

Poly(dimethylsiloxane) (PDMS)/montmorillonite (MMT) composites have been prepared using a newly synthesized omega-ammonium functionalized poly(dimethylsiloxane) compatibilizer coupled with a dispersion technique in water. The organoclay containing the new siloxane surfactant was characterized by TGA and XRD. For the first time, a nanoscopic dispersion of MMT nanoplatelets in the PDMS composite cured by hydrosilylation and a good compatibility between clay layers and matrix were obtained. The beneficial effect of both the surfactant and the water onto clay nanoplatelet dispersion was evaluated by different microscopy techniques and by measuring different properties such as the viscosity of the uncured PDMS/MMT nanodispersions, and the swelling rate and Young's modulus of the cured PDMS/MMT nanocomposites.

Effects of silicone surfactant on the cell size and thermal conductivity of rigid polyurethane foams by environmentally friendly blowing agents

Rigid polyurethane foams (PUF)s were synthesized with environmentally friendly blowing agents such as a cyclopentane/distilled water (10.0/1.0, pphp) mixture and distilled water only for four different silicone surfactants having different silicone/polyether ratios. An attempt was made to reduce the thermal conductivities of the PUF samples by varying the concentration and the silicone/polyether ratio of the various silicone surfactants. The scanning electron microscopy (SEM) results indicated an optimum concentration of the silicone surfactant of about 1.5 to 2.5 phpp for various surfactants to reduce the cell size and lower the thermal conductivity. The silicone surfactant having a higher silicone/polymer ratio showed a smaller cell size and, therefore, demonstrated the lower thermal conductivity of the PUF samples. From the relation between the thermal conductivity and the cell size of the PUF samples, the smaller cell size improved the thermal insulation property of the rigid PUF for both the PUF samples blown by the cyclopentane/distilled water (10.0/1.0, pphp) mixture and distilled water only. If the blowing agent is fixed, then the cell size is an important factor to decrease the thermal conductivity of the PUF samples. These results indicated that rigid PUF samples having lower thermal conductivity can be obtained by choosing a silicone surfactant containing a higher silicone/polyether ratio, as well as an optimum content of the surfactant.

Preparation of pressure-sensitive adhesives for the production of sticky foam at ambient temperature

In this paper, formulations for producing thermoplastic sticky foam, useful in preventing, delaying, or impeding access to protected materials or areas for military or law enforcement purpose, were investigated. Various formulations of pressure-sensitive adhesives (PSAs) using different amounts of thermoplastic elastomers (isoprene or Kraton D), tackifying agent (petroleum resin), chlorinated paraffin and silicone surfactant were prepared in toluene at ambient temperature. After vacuum stripping the solvent, the stability of the formulations and their tack properties (by tensile and hold tests) were determined. Combinations of the optimized formulations with different foaming agents were studied and compared concerning the expansion ratio and the stability of the foam (t1/2 life time). A thermoplastic sticky foam with a density of 20kg/m3 and a foam stability of 30min (t1/2) can be obtained by mixing two foaming agents (CHClF2 and CO2) with the optimized composition (comprising 60 parts of isoperene, 40 parts of petroleum resin, 50 parts of silicone surfactant and 250 parts of chlorinated paraffin (formulation no. 8)) in a pressurized vessel and releasing the contents to atmospheric pressure.

Development of Surfactants and Builders in Detergent Formulations

Surfactants and builders are the two most important ingredients in laundry, household and personal-care cleaning products. They play a key role in washing processes. The development of various surfactants ( e.g., anionic, nonionic, cationic, zwitterionic, and silicone surfactants) and builders (inorganic, organic and polymeric builders) used in the detergent compositions are reviewed and their detergency performance and biodegradability are discussed. In the future, the development of the surfactants and builders used in detergent compositions should be based on economic and environmental considerations. The use of the eco-friendly surfactants and builders derived from inexpensive renewable resources ( e.g., alkyl polyglucosides and bio-based polyesters) in detergent compositions is the developing trends in detergent industry.

Equilibrium partition of polycyclic aromatic hydrocarbons in cloud point extraction with a silicone surfactant

In the cloud point extraction (CPE) process with PEG/PPG-18/18 dimethicone, the flexible chain structure of the silicone surfactant efficiently decreased the water content remaining in the surfactant-rich phase, compared with conventional nonionic surfactants, represented by Triton X-114. Meanwhile, the phase volume ratio of surfactant-rich phase to aqueous phase obtained in the silicone surfactant CPE system was found to be maintained at a low value with increasing surfactant concentration; whereas a rapid increase tendency was commonly observed in that of other nonionic surfactants. Based on these advantages, the equilibrium partition of three polycyclic aromatic hydrocarbons (PAHs), anthracene, phenanthrene and pyrene, was studied in the CPE process with PEG/PPG-18/18 dimethicone. Equilibrium parameters, including preconcentration factor, distribution coefficient and recovery, were determined, and the performance was compared with that of another related CPE research, where Tergitol 15-S-7 was used. Due to the low surfactant-rich phase volume, higher concentrations of the three PAHs in the surfactant-rich phase, and the resulting higher preconcentration factors and distribution coefficients were able to be achieved at the same time. Moreover, the great performance was able to be maintained even at a high surfactant concentration or PAHs initial concentration.

Cloud Point Extraction of Polycyclic Aromatic Hydrocarbons in Aqueous Solution with Silicone Surfactants

Abstract Cloud point extraction (CPE) processes with two silicone surfactants, Dow Corning DC-190 and DC-193, were studied as preconcentration and treatment for the water polluted by three trace polycyclic aromatic hydrocarbons (PAHs): anthracene, phenanthrene and pyrene. For all cases, the volumes of surfactant-rich phase obtained by two silicone surfactants were very small, i.e. a lower water content in the surfactant-rich phase was obtained. For example, less than 3% of the initial solution was obtained in a 1% (by mass) surfactant solution, which was much smaller than that of TX-114 in the same surfactant concentration. And TX-114 is known as a high compact surfactant-rich phase among most nonionic surfactants, thus the comparison showed that an excellent enrichment was ensured in the analysis application by the CPE process with the silicone surfactants, and the lower water content obtained in the surfactant-rich phase is also important in the large scale water treatment. The influences of additives and phase separation methodology on the recovery of PAHs were discussed. Comparing with DC-193. DC-190 has a lower cloud point and a higher recovery (near 100%) of all the three PAHs in same surfactant concentration, which was required for application as a preconcentration process prior to HPLC system. However the DC-190 solution is hard to be phase separated only by heating, whereas DC-193 has a relative higher phase separating speed by heating, but a high cloud point (around 360K) limits its application. Due to the phase separation by heating is the only method of CPE suitable to the large scale water treatment, the mixtures of two silicone surfactants solutions were investigated in this study. A solution containing 1% of mixed DC-190 and DC-193 (in the ratio of 90:10) removed anthracene, phenanthrene and pyrene near 100% with a relative low cloud point and quick phase separating speed.

Influence of PEG‐12 Dimethicone addition on stability and formation of emulsions containing liquid crystal

Oil/water emulsions, containing liquid crystals, were developed employing Andiroba oil, PEG-12 Dimethicone and Crodafos CES. It was evaluated the influence of silicone surfactants on the emulsions stability and on the formation of liquid crystalline phases and therefore, physicochemical characteristics, such as rheology and zeta potential, were evaluated. Emulsions were prepared by the emulsions phase inversion method. All the formulations presented lamellar liquid crystalline phases. The PEG-12 Dimethicone addition did not change microscopically the liquid crystalline phases. The emulsions containing silicone demonstrated lower viscosity than those without the additive. This is an important feature, as the silicone did not change the rheological profile; however, the addition of silicone still can be used as a viscosity controller. The formulations had their viscosity increased 15 and 150 days after their preparation. This characteristic shows that the emulsions have their organization increased along the storing time. In the analysis of zeta potential, we could verify that all formulations presented negative values between -39.7 and -70.0 mV. Within this range of values, the emulsion physical stability is high (Fig. 10). It was concluded that the addition of PEG-12 Dimethicone kept the liquid crystalline phase of the emulsion obtained with Crodafos CES, influencing in a positive way in the system stability.

Efficacy of Glyphosate Plus Bentazon or Quizalofop on Glyphosate-Resistant Canola or Corn

Greenhouse experiments were conducted to determine the effect of glyphosate on efficacy of bentazon for glyphosate-resistant (GR) canola control and of quizalofop for GR corn control. Control also was evaluated for glyphosate plus bentazon on wild buckwheat and wheat and glyphosate plus quizalofop on velvetleaf. Glyphosate plus bentazon synergistically controlled GR canola and wild buckwheat but were antagonistic for wheat control. Glyphosate plus quizalofop were additive for control of GR corn and velvetleaf. Inert ingredients in glyphosate formulations, i.e., cationic surfactant, NH4, or K, contributed to glyphosate synergism of bentazon, but the major contribution came from glyphosate itself. Efficacy of glyphosate plus bentazon on GR canola was enhanced by ammonium nitrate (AMN), ammonium sulfate (AMS), nonionic surfactant (NIS), or silicone surfactant (SiS) but was slightly decreased by methylated seed oil (MSO) or petroleum oil concentrate. AMN, AMS, NIS, and SiS partially overcame the antagonism of bentazon to glyphosate for wheat control. NIS enhanced phytotoxicity of glyphosate plus quizalofop to GR corn and velvetleaf, but the enhancement was less than by SiS or MSO to GR corn and SiS or AMS to velvetleaf.