Case IV (D) Adherent Controlled Release Pesticide

This invention relates to methods and compositions for the controlled release of bioactive agents and, more particularly, to the controlled release of pesticides, such as insecticides.

The utilization of bioactive agents such as pesticides, e.g., insecticides, herbicides and fungicides has become an important fact of life. However, these materials are generally effective only as long as they persist on the substrate to which they are applied.

The basic motivation underlying the modern development of controlled release pesticidal materials has been to extend the duration between applications and thus increase the efficiency and hence economy of control. Controlled release of pesticides permits extended time intervals between treatments and reduction of the dosage, thus reducing environmental impact. Thus, from an ecological standpoint, controlled release of pesticides enhances the lifetime of a non-persistent agent at the site of treatment while maintaining the preferred property of rapid detoxification in the environment surrounding the controlled release pesticide.

The desired controlled release of pesticides has previously been achieved by their incorporation within a polymeric matrix, e.g., encapsulation wherein a pest control agent is surrounded by an enveloping polymeric wall that permits loss through diffusion, permeation or degradation; dispersion of the pesticide in an elastomer or a plastic wherein the pesticide is released through leaching or diffusion; and the chemical combination of the pesticide with a polymer in such a manner that the appended pesticide slowly breaks off the polymeric backbone upon exposure to the pest infected environment. However, the prior art approaches fall short of the desired goal in that there is not adequate provision for the adhesion of the pesticide within the polymeric matrix to the substrate. This permits the removal or transfer of the material from the substrate as a result of physical contact, wind, rain or other atmospheric conditions.

One object of the present invention is to provide a process for the controlled release of bioactive agents such as pesticides.

Another object of the present invention is to improve the adhesion of such an agent of suitable substrates and thus to increase its effective lifetime.

Another object of the present invention is to provide stable compositions which after application to a suitable substrate and exposure to the atmosphere, undergo in situ chemical reaction resulting in adherent insecticides with controlled release characteristics.

A further object of the present invention is to provide novel compositions containing reactive polysiloxanes, adhesion promoting, crosslinking reactive silanes and insecticides.

These and other objects of the present invention are achieved by using a mixture consisting of (a) an organopolysiloxane containing hydroxyl groups or functional groups which are hydrolyzable to hydroxyl groups, (b) a hydrolyzable silane selected from the group consisting of (1) a hydrocarbon substituted hydrolyzable silane, (2) an organopolysiloxane containing hydrolyzable silane groups, and (3) a partial hydrolyzate of (1) and/or (2), and (c) an insecticide.

The organopolysiloxanes suitable for use in the practice of the present invention are well known in the art and contain the structural unit ##STR1## wherein X is a hydroxyl radical or a hydrolyzable radical such as alkoxy, acyloxy, hydrogen, halogen and the like and R and R' are oxygen (i.e., the group --O--) or non-hydrolyzable hydrocarbon, substituted hydrocarbon or heterocyclic radicals and are the same or different. When R and R' are hydrocarbon radicals, they may be acyclic or cyclic, saturated or unsaturated and include aliphatic radicals such as methyl, ethyl, vinyl, propyl, allyl, butyl, crotyl, hexyl, decyl, dodecyl, hexadecyl, octadecyl, octadecenyl radicals and the like as well as halogenated or other substituted aliphatic radicals, aromatic radicals such as phenyl, biphenyl, phenoxyphenyl and naphthyl radicals as well as halogenated and other substituted aromatic radicals, aralkyl radicals such as benzyl and phenylethyl radicals, alkylaryl radicals such as tolyl and xylyl radicals, cycloaliphatic radicals such as cyclopropyl, cyclopentyl, cyclopentenyl, cyclohexyl and cyclohexenyl radicals and heterocyclic radicals such as furfuryl radicals.

The organopolysiloxanes may be linear, branched or both linear and branched and the X radicals may be terminal end groups or may be situated at other sites in the polysiloxane chain. The number of X radicals may range from one radical per polysiloxane molecule up to 30 weight percent of the total organopolysiloxane molecular weight.

The polysiloxane may be predominantly a monoorganopolysiloxane, a diorganopolysiloxane, a copolymer containing monoorganosiloxane units and diorganosiloxane units, a copolymer containing triorganosiloxane units and SiO.sub.2 units and the like. Notwithstanding the predominant structure, the organopolysiloxane may contain varying amounts of the other structural units in addition to hydroxyl radicals or radicals hydrolyzable thereto.

The polysiloxanes suitable for use in the practice of the present invention are well known in the art and may be prepared by various procedures including controlled hydrolysis of appropriate precursors as well as ring opening polymerization of cyclic organopolysiloxanes.

The controlled hydrolysis and cohydrolysis of RSiX.sub.3, R.sub.2 SiX.sub.2, R.sub.3 SiX and SiX.sub.4, where X is a hydrolyzable radical as previously defined, yields organopolysiloxanes containing monoorganosiloxane, diorganosiloxane, triorganosiloxane and SiO.sub.2 units, respectively. The relative proportions of said units in the organopolysiloxane are determined by employing the appropriate ratios of hydrolyzable precursors. In order to be useful in the practice of the present invention, the resultant organopolysiloxane must be readily soluble or dispersible in organic solvents and contain residual hydroxyl or hydrolyzable radicals.

The polymerization of cyclic organopolysiloxanes provides another route to the preparation of organopolysiloxanes containing hydroxyl or hydrolyzable radicals which may be employed in the practice of the present invention. These and other methods of preparation are set forth in K. A. Andrianov, "Metalorganic Polymers", Interscience Publishers, New York, 1965, Chapter III, pages 109-275, the disclosures of which are incorporated herein by reference.

Polysiloxanes which are at an intermediate stage of polymerization in that they contain hydroxyl radicals which, upon application of heat, may undergo condensation to a more advanced stage of polymerization or in that they contain hydrolyzable groups which upon further hydrolysis may proceed to a more advanced stage of polymerization are suitable for use in the practice of the present invention if they have not been rendered insoluble in organic solvents.

The organopolysiloxanes may be fluids of low or high viscosity or even solids. The physical appearance of the polysiloxane is dependent upon the nature of the R and R' radicals, the presence of linear or branched structures as well as the molecular weight. Notwithstanding the physical appearance of the polysiloxane, the important requirement for utility in the practice of the present invention is the presence of hydroxyl radicals or radicals hydrolyzable thereto. Mixtures of such polysiloxanes are suitable for use in the present invention.

The hydrolyzable silanes suitable for use in the practice of the present invention have the formula:

where R is a monovalent hydrocarbon radical, X is a hydrolyzable group such as halogen, alkoxy, acyloxy, hydrogen and the like, and n is an integer from 0 to 2, inclusive. When X is an alkoxy group, OR', or an acyloxy group, OCOR', R' may be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, 2-ethylhexyl or other aliphatic hydrocarbon radical of less than 10 carbon atoms. Preferably R' is a lower alkyl radical of no more than 4 carbon atoms. All of the X's may be the same or they may be different. The hydrocarbon radical R may be cyclic or acyclic, saturated or unsaturated, aliphatic or aromatic and include the alkyl, aryl, alkenyl, aralkenyl, cycloalkyl, cycloalkenyl and heterocyclic radicals such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, amyl, hexyl, vinyl, allyl, chloroallyl, methallyl, crotyl, butadienyl, phenyl, dichlorophenyl, pentachlorophenyl, xylyl, benzyl, styryl, cinnamyl, furfuryl, cyclohexyl, cyclopentadienyl, cyclopentenyl, pyridyl, etc. radicals. The hydrocarbon R may also be a substituted alkyl R"(CH.sub.2).sub.x where x is an integer from 1 to 20 inclusive and R" is a polar and/or reactive functionality such as acryloxy, methacryloxy, glycidoxy, epoxycyclohexyl, mercapto, amino, ureido, halo, etc. radicals. There are numerous commercial materials of this type which are commonly known as organofunctional silane coupling agents or adhesion promoters.

The monomeric hydrolyzable silanes may be subjected to partial hydrolysis to promote the formation of condensation products which are still hydrolyzable silanes and are suitable for use in the practice of the present invention.

The organopolysiloxanes containing pendant or terminal hydrolyzable silane radicals, suitable for use in the practice of the present invention, have the formula:

where P is an organopolysiloxane as hereinafter defined, X is a hydrolyzable group such as halogen, alkoxy, acyloxy, hydrogen, and the like, n is an integer from 2 to 3 and m is an integer from 1 to 20. When X is an alkoxy group OR' or an acyloxy group OCOR', R' may be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, 2-ethylhexyl or other aliphatic hydrocarbon radical of less than 10 carbon atoms. Preferably, R' is a lower alkyl radical of no more than 4 carbon atoms. All the X's may be the same or they may be different.

The organopolysiloxanes are well known in the art and contain the structural unit: ##STR2## where R'" and R"" are oxygen (i.e., the group --O--) or non-hydrolyzable hydrocarbon, substituted hydrocarbon or heterocyclic radicals and are the same or different. When R'" and R"" are hydrocarbon radicals, they may be acyclic or cyclic, saturated or unsaturated and include aliphatic radicals such as methyl, ethyl, vinyl, propyl, allyl, butyl, crotyl, hexyl, decyl, dodecyl, hexadecyl, octadecyl, octadecenyl radicals and the like as well as halogenated or other substituted aliphatic radicals, aromatic radicals such as phenyl, biphenyl, phenoxyphenyl and naphthyl radicals as well as halogenated and other substituted aromatic radicals, aralkyl radicals such as benzyl and phenylethyl radicals, alkylaryl radicals such as tolyl and xylyl radicals, cycloaliphatic radicals such as cyclopropyl, cyclopentyl, cyclopentenyl, cyclohexyl and cyclohexenyl radicals and heterocyclic radicals such as furfuryl radicals.

The organopolysiloxanes may be linear, branched or both linear and branched. The polysiloxane may be predominantly a monoorganopolysiloxane, a diorganopolysiloxane, a copolymer containing monoorganosiloxane units and diorganosiloxane units, a copolymer containing triorganosiloxane units and SiO.sub.2 units and the like. Notwithstanding the predominant structure, the organopolysiloxane may contain varying amounts of other structural units, in addition to hydrolyzable silane radicals.

The polysiloxanes containing hydrolyzable silane radicals, suitable for use in the practice of the present invention, may be prepared from organopolysiloxanes which are well known in the art. The latter may be prepared by various procedures including controlled hydrolysis of appropriate precursors as well as ring opening polymerization of cyclic organopolysiloxanes.

The controlled hydrolysis and cohydrolysis of RSiX.sub.3, R.sub.2 SiX.sub.2, R.sub.3 SiX and SiX.sub.4, where X is a hydrolyzable radical as previously defined, yields organopolysiloxanes containing monoorganosiloxane, diorganosiloxane, triorganosiloxane and SiO.sub.2 units, respectively. The relative proportions of said units in the organopolysiloxane are determined by employing the appropriate proportions of hydrolyzable precursors. In order to be useful in the preparation of polysiloxanes containing hydrolyzable silane radicals, the precursor organopolysiloxanes must be readily soluble or dispersible in organic solvents and contain residual reactive radicals such as hydroxyl, alkoxyl, acyloxyl, halogen, hydrogen, vinyl, allyl and the like.

The polymerization of cyclic organopolysiloxanes provides another route to the preparation of organopolysiloxanes containing reactive radicals which may be employed in the preparation of the organopolysiloxanes containing hydrolyzable silane radicals which are suitable for use in the practice of the present invention. These and other methods of preparation are set forth in K. A. Andrianov, "Metalorganic Polymers", Interscience Publishers, New York, 1965, Chapter III, pages 109-275, the disclosures of which are incorporated herein by reference.

Polysiloxanes which are at an intermediate stage of polymerization in that they contain hydroxyl radicals which, upon application of heat, may undergo condensation to a more advanced stage of polymerization or in that they contain hydrolyzable groups which upon further hydrolysis may proceed to a more advanced stage of polymerization, if they have not been rendered insoluble in organic solvents, are suitable precursors for the preparation of the organopolysiloxanes containing hydrolyzable silanes which may be used in the practice of the present invention.

The organopolysiloxanes containing hydrolyzable silanes may be prepared by reactions well known in the art. Thus, reaction of an organopolysiloxane containing hydroxyl groups with excess silicon tetraacetate yields the triacetoxysilane as shown by the following reaction: ##STR3## wherein P is as previously defined. Similarly, reaction with an alkyl or aryltriacetoxysilane yields the corresponding diacetoxysilane as disclosed in U.S. Pat. No. 3,035,016, the disclosure of which is incorporated herein by reference. This reaction is shown below: ##STR4## wherein P and R'" are the same as previously defined.

The reaction of an organopolysiloxane containing SiH units, e.g., as prepared by hydrolysis and cohydrolysis of a dichlorosilane with an unsaturated trialkoxysilane or triacyloxysilane in the presence of chloroplatinic acid, yields an organopolysiloxane containing hydrolyzable radicals, suitable for use in the practice of the present invention as shown by the following reaction: ##STR5## wherein P and R'" are the same as previously defined.

Organopolysiloxanes containing vinyl unsaturation, e.g., as prepared by cohydrolysis of mixtures of various chlorosilanes including vinylalkylchlorosilanes, may be reacted with trialkoxysilane to yield organopolysiloxanes containing hydrolyzable silane radicals suitable for use in the present invention as shown by the following equation:

wherein P and R'" are the same as previously described.

Alternative methods of preparing organopolysiloxanes suitable for use in the practice of the present invention will be obvious to those skilled in the art. Notwithstanding the method of preparation, the presence of SiX.sub.2-3 radicals as pendant or terminal units in an organopolysiloxane renders it suitable for use in the present invention.

The organopolysiloxanes containing hydrolyzable silane radicals may be fluids of low or high viscosity or even solids. The physical appearance of the polysiloxane is dependent upon the nature of the R'" and R"" radicals, the presence of linear or branched structures as well as the molecular weight. Notwithstanding the physical appearance of the polysiloxane, the important requirement for utility in the practice of the present invention is the presence of hydrolyzable silane radicals. Mixtures of such polysiloxanes are suitable for use in the present invention.

The preferred compositions of the present invention contain organopolysiloxanes containing hydroxyl groups and hydrolyzable silanes in weight ratios from 10/90 to 95/5.

While hydrolyzability is a general characteristic of the silanes which may be used in the practice of the present invention, the rate of hydrolysis is a function of the nature of the hydrocarbon substituent in the hydrolyzable group. Thus, the presence of methyl radicals results in rapid hydrolysis while higher alkyl radicals result in slower hydrolysis. In the latter case, it is possible to use water as a diluent or dispersing medium during the preparation and handling of the active compositions, and as the hydrolyzing reaction as the composition is applied or after it is applied to the substrate.

Insecticides which may be used in the practice of this invention include any of the compounds well known in the art for use as insecticides such as those set forth in Chemical Week, June 21, 1972, pages 39-64; Chemical Week, July 16, 1972, pages 19-41; and Commercial and Experimental Organic Insecticides (1974 Revision), Entomological Society of America, Special Publication 74-1, October 1974. Some common insecticides which may be used include the following:

1-naphthyl methylcarbamate (SEVIN)--pyrethrins

malathion--parathoin

methylparathion--phorate

toxaphene--chlordane

Dursban--Baygon

Ddt--diazinon

The insecticides which may be used in the practice of this invention also include bacterial insecticides such as Bacillus popilliae and Bacillus thuringiensis and viral insecticides such as the Heliothis virus. These have been described in Chemical & Engineering News, 35, No. 30, 18 (July 28, 1975), the disclosures of which are incorporated herein by reference.

The insecticide is included in the composition in an amount sufficient to exert an insecticidal action on the immediate environment surrounding the substrate. The amount of insecticide will be dependent upon several factors such as the composition and thickness of the cured polymeric matrix, the nature of the insecticide, i.e., liquid or solid, the presence of active hydrogen functionality, the duration of insecticidal action desired, etc. The optimum amount of insecticide to be included may readily be determined by those skilled in the art. Generally, from about 1 part by weight of insecticide to 0.5 to 1000 parts of the combined weight of polysiloxane and silane is satisfactory.

The compositions of this invention may include volatile diluents such as aliphatic or aromatic hydrocarbons, e.g., Stoddard Solvent, mineral spirits, B&P naphtha, cyclohexane, petroleum ether, benzene, toluene, xylene, etc., chlorinated hydrocarbons such as perchloroethylene or volatile fluid polysiloxanes such as dimethylpolysiloxane fluids. The compositions may be prepared by merely admixing the various components. Before admixing, the components may be dispersed or dissolved in a diluent such as previously described. The compositions may also be prepared in aqueous media when slowly hydrolyzing and/or stable components are present.

The compositions of this invention may be applied to a large number of substrates. The substrate should be one which contains active hydrogen atoms which provide sites for coupling with the polysiloxane-silane system, e.g., hydroxyl groups, amino groups, etc. Thus, various plants such as ornamental bushes, trees, flowers, greenhouse plants, lawns, crops, (e.g., wheat, corn, soy beans, barley, oats, cotton, jute, sisle), fruits, vegetables, berry bushes, nut trees, olive trees, fig trees, grape vines; various animals such as household pets (e.g., cats, dogs), farm animals such as dairy cattle, beef cattle, horses, sheep, chickens, turkeys, swine, goats, zoo animals, etc. Non-plant and animal uses include spraying surfaces of structures such as buildings and various rooms in buildings, such as kitchens, bathrooms, closets including wood or plaster board walls and floor tile to protect against roaches, termites, flying insects, rug insects, ants, etc. Various containers such as bags and cardboard or wooden boxes may also serve as substrates in accordance with the practice of this invention.

The compositions of this invention may be applied to the substrate by brushing, spraying, dipping or any other known technique for applying a fluid composition to a solid substrate. It may be applied in the form of an aerosol mist or fog, propelled by conventional pressurized volatile halohydrocarbon, hydrocarbon or compressed gas propellants, an air propelled mist blower, a fog generator, or other suitable means.

Although this invention should not be limited thereby, it is believed that upon application of the compositions of this invention to a suitable substrate in an ambient atmosphere, evaporation of the volatile diluent, if any is present, and exposure to atmospheric moisture results in the hydrolysis of the hydrolyzable silane, followed by condensation of the Si(OH).sub.x groups generated thereby with the SiOH groups present or generated by hydrolysis on the organopolysiloxane to form a crosslinked polysiloxane matrix containing entrapped or occluded insecticide. Simultaneously, the Si(OH).sub.x groups promote the adhesion of the polymeric matrix and the insecticide entrapped or occluded therein to the substrate. Adhesion to the substrate is due at least in part to the fact that the polysiloxane matrix is coupled to the substrate by reaction through active hydrogen atoms on the substrate. In this manner, the insecticide is held on the substrate to such an extent that it cannot be physically brushed off, blown off or washed off by rain. Further, as a result of its entrapped condition the rapid evaporation, sublimation or extraction of the insecticide is retarded. However, due to the permeability of the polysiloxane to organic compounds, said evaporation or sublimation is not completely inhibited, resulting in controlled release of the insecticide.

When water is present in the compositions of this invention, said water is generally added shortly before application of the composition to a suitable substrate, and hydrolysis of the silane may begin before or during application to said substrate. However, hydrolysis continues after said application and is followed by condensation of the SiOH groups generated thereby with the SiOH groups present or generated by hydrolysis on the organopolysiloxane.

The rate of crosslinking of the hydrolyzable silane, after moisture induced hydrolysis, may be increased by the use of catalysts, such as tin soaps including stannous octoate and dibutyl tin dilaurate. Thus, the volatility of a low viscosity, low molecular weight alkoxysilane such as methyl triethoxysilane or tetraethyl orthosilicate, may result in loss by evaporation before sufficient hydrolysis followed by condensation can increase the viscosity and retard evaporation. The rate of condensation is increased in the presence of a catalyst, resulting in a rapid viscosity increase and decreased volatility.

The rate of release may be controlled by adjusting the extent of crosslinking, e.g., by adjusting the polysiloxane/silane ratio, the thickness of the polysiloxane coating, e.g., by modifying the composition and concentration of reactive components in the solution thereof, or by adding a non-volatile, non-reactive extender for the crosslinked polysiloxane. The latter acts in a manner analogous to the behavior of the hydrocarbon oil in a vulcanized oil-extended hydrocarbon rubber. The extender may be a compatible non-siloxane compound, e.g., a hydrocarbon oil, or may be an alkyl or arylpolysiloxane fluid having a viscosity ranging from 5 to 100,000 centistokes at 25.degree. C.

In addition to or in lieu of the solvents which function to reduce the viscosity of the compositions of this invention as well as control the thickness of the polysiloxane coating, volatile alcohols such as ethanol, isopropanol, butanol and the like may be included in the composition to prevent premature hydrolysis of the hydrolyzable crosslinking agent with resultant gelation and precipitation.

Other additives which may be incorporated into the compositions of this invention include stabilizers against environmental degradation, such as antioxidants and ultraviolet stabilizers, odor masking compounds and perfumes, dyes, pigments, fillers, etc.

The following examples illustrate the best modes for carrying out this invention. Examples I to III illustrate the improved adhesion of the compositions of this invention to a substrate. In the tables in these examples, the numbers refer to the amount of materials in parts by weight.

Solutions cntaining 50 weight-% of one or more of the following components were prepared in anhydrous isooctane: (a) methyltriethoxysilane designated as A-162 by Union Carbide Corporation, (b) a linear dimethylpolysiloxane fluid containing 3 weight-% hydroxyl groups and having a viscosity of 80 centistokes at 25.degree. C., designated as F1-3563 by the Dow Corning Corp., and (c) a dimethylpolysiloxane fluid, designated as a DC-200 fluid by the Dow Corning Corp., having a viscosity of 1000 centistokes at 25.degree. C. (DC-200/1000).

The 50% solutions of alkoxysilane, silanol and/or polysiloxane fluid in isooctane were mixed with a pyrethroid composition as follows:

0.1 g. pyrethroids

0.5 g. piperonyl butoxide

0.4 g. petroleum distillate

5.0 g. 50% solution of A-162, F1-3563 and/or DC-200/1000 in isooctane

The 50% pyrethroid-containing solutions were diluted to 10 weight-% with isooctane and 10-20 drops were placed on a weighed glass slide. A glass rod was rolled over the solution to spread the material uniformly over the lower four fifths of the slide. The coated slide was air dried for 4 hours and then placed in a 50% relative humidity chamber for 18 hours. The slide was then weighed to determine the weight of the coating which ranged from 2-5 mg. covering an area of 15 sq. cm. The coated slide was inserted into a slit rubber stopper and mounted over the center of a Waring Blender. The coated slide faced the moving water which completely covered the coating. The blender was operated at its highest speed for 5 minutes. The slide was air dried overnight and then weighed to determine the amount of coating retained on the slide after the treatment in the Blender. The average results of duplicate tests are summarized in Table 1, where the amount of pyrethroids indicated actually represents the sum of the pyrethroids and piperonyl butoxide.

In the absence of the moisture curable alkoxysilane, the silanol and/or polysiloxane fluid compositions containing the pyrethroids had little or no retention. However, when the alkoxysilane was present, the retention was greatly improved.

Solutions containing 50 weight-% of one or more of the following components were prepared in anhydrous isooctane: (a) tetraethyl orthosilicate (ES-100), (b) a linear dimethylpolysiloxane fluid containing 3 weight-% hydroxyl groups (F1-3563), and (c) a dimethylpolysiloxane fluid having a viscosity of 1000 centistokes at 25.degree. C. (DC-200/1000).

The solutions were diluted, coated on glass slides, dried, moisture cured at 50% relative humidity for 18 hours and subjected to treatment with water in the Waring Blender as described in Example I. The results are summarized in Table 2.

The volatility and slow hydrolysis of the tetraethyl orthosilicate results in poor crosslinking and low retention (No. 8) unless a catalyst is present (No. 12). The presence of the viscous polysiloxane fluid (No. 10) retards volatilization. The polysiloxane generated by the silicate-silanol reaction has almost complete retention due to the excellent adhesion resulting from the interaction of the hydrolyzed alkoxysilane, i.e., silicate, units with the glass surface, accompanying the reaction with the silanol.

When the compositions of Table 2 were mixed with a pyrethroids solution, as in Example I, the relative adhesion, i.e., retention, results were in the same order as those obtained in the absence of the pesticide.

Solutions containing 50 weight-% of one or more of the following components were prepared in anhydrous isooctane: (a) tetraethyl orthosilicate (ES-100), (b) a methylmethoxypolysiloxane fluid copolymer containing 30 weight-% methoxy groups and having a viscosity of 40 centistokes at 25.degree. C., designated as F4-3597 by the Dow Corning Corp., and (c) a DC-200 fluid having a viscosity of 1000 centistokes at 25.degree. C. (DC-200/1000).

The solutions were diluted, coated on glass slides, dried, moisture cured at 50% relative humidity for 18 hours and subjected to treatment with water in the Waring Blender, as described in Example I. The results are summarized in Table 3.

The highest retention is obtained as a result of the interaction of the hydrolyzed tetraethyl orthosilicate and the hydrolyzed methoxysilane. Similar results are obtained when pyrethroids are present.

A 250 ml. 3-necked flask equipped with a stirrer, thermometer, dropping funnel, condenser and nitrogen inlet was charged under nitrogen with 160 g. (0.07 mole) of a methylhydrogenpolysiloxane, containing 35 methylhydrogensiloxy units and 2 trimethylsiloxy terminal units, and 0.27 g. chloroplatinic acid. A total of 53.9 g. (0.28 mole) of vinyltriethoxysilane was added over a period of 1 hour to the reaction mixture which had been heated to 80.degree. C. The temperature rose and was maintained at 110.degree. C. for an additional hour. The reaction mixture was cooled to 25.degree. C. and filtered under nitrogen to remove the black catalyst particles. The filtrate was kept at 25.degree. C. at 0.1 mm. pressure for 20 hours to remove residual vinyltriethoxysilane. The product was obtained in a yield of 92% and was analyzed for ethoxy content by acetylation and hydrolysis, in accordance with the procedure of A. L. Smith, "Analysis of Silicones", Wiley-Interscience, 1974, p. 154. The triethoxysilylethylated methylhydrogenpolysiloxane had an ethoxy content of 14.3 weight-%.

A solution containing 50 weight-% non-volatiles was prepared as follows:

10 g. triethoxysilylethylated methylhydrogenpolysiloxane (14 wt-% OC.sub.2 H.sub.5) of Example IV (TESEPS)

40 g. dimethylpolysiloxane F1-3563 (3 wt-% OH)

50 g. perchloroethylene

The polysiloxanylalkoxysilane-dimethylpolysiloxane solution was mixed with a pyrethroid composition to yield an insecticide-containing solution which was compared with an additive-free pyrethroid composition for insecticidal behavior. The components of the test compositions were as follows:

A disposable plastic syringe was used to place the test solution on a 4.times.4 inch glas panel. The solution was uniformly spread over the panel with the tip of the syringe. The treated panels were conditioned for 24 hours in a chamber at 78.degree. F. and 48% relative humidity. Ten adult male German cockroaches, Blattella germanica (Linnaeus), were exposed to the 1 day residue for 24 hours under a 100.times.15 mm. petri dish. The test was conducted in duplicate. The same treated panels were reexposed to cockroaches after 3, 7 and 10 days.

The percent mortality of cockroaches exposed to the treated glass panels is summarized below:

The residue from the control insecticide solution VB was ineffective after 7 days while the residue from insecticide solution VA, containing the polysiloxanylalkoxysilane-dimethylpolysiloxane composition, killed 95% of the exposed cockroaches after 7 days and 65% after 10 days.

On the 11th day the panel containing the residue from solution VA was subjected to treatment with water in a Waring Blender for 5 min., as described in Example I, and then reexposed to cockroaches after a total residue age of 15 days. Despite the vigorous water treatment, the residue still killed 5% of the exposed cockroaches.

The following solutions containing 50 weight-% of active components were prepared in anhydrous icooctane: (a) dimethylpolysiloxane fluid DC-200/1000, and (b) methyltriethyloxysilane (A-162), methylmethoxypolysiloxane copolymer containing 30 weight-% methoxy groups (F4-3597), DC-200/1000 dimethyl polysiloxane fluid and stannous octoate in 10/10/80/0.05 weight ratio.

The 50% solutions were mixed with a pyrethroid composition as follows:

0.1 g. pyrethroids

0.5 g. piperonyl butoxide

0.4 g. petroleum distillate

5.0 g. 50% solution of DC-200/1000 or A-162-F4-3597-DC-200/1000-stannous octoate in isooctane

The solutions were diluted, coated on glass slides, dried, moisture cured at 50% relative humidity for 18 hours and subjected to treatment with water in the Waring Blender, as described in Example I. The averaged results of duplicate tests are summarized in Table 4, where the amount of pyrethroids indicated actually represents the sum of the pyrethroids and piperonyl butoxide.

The adhesion promoting effect of the hydrolyzed alkoxysilane-alkoxypolysiloxane reaction is apparent.

A solution containing a 50 weight-% non-volatiles was prepared as follows:

5 g. methyltriethoxysilane (A-162)

5 g. methylmethoxypolysiloxane F4-3597 (30 wt-% OCH.sub.3)

0.0125 g. stannous octoate

40 g. DC-200/1000 dimethylpolysiloxane fluid

50 g. perchloroethylene

The alkoxysilane-alkoxypolysiloxane-dimethylpolysiloxane solution was mixed with a pyrethroid composition to yield an insecticide-containing solution which was compared with an additive-free pyrethroid composition for insecticidal behavior. The components of the test compositions were as follows:

The insecticidal properties of solutions VIIA and VIIB were evaluated using adult cockroaches as the test species and glass as the test surface, as described in Example V. The treated glass panels were exposed, in duplicate, to cockroaches after 1, 3, 7 and 10 days.

The percent mortality of cockroaches exposed to the treated glass panels is summarized below:

The residue from the control insecticide solution VIIB was ineffective after 7 days while the residue from insecticide solution VIIA, containing the alkoxysilane-alkoxypolysiloxane-dimethylpolysiloxane composition, killed 75% of the exposed cockroaches after 7 days and 50% after 10 days.

On the 11th day the panel containing the residue from solution VIIA was subjected to treatment with water in a Waring Blender for 5 min., as described in Example I, and then reexposed to cockroaches after a total residue age of 15 days. On the 16th day the panel was again subjected to treatment with water and then reexposed to cockroaches after a total residue age of 18 days.

The percent mortality of cockroaches exposed to the treated glass panels is summarized below:

The residue from insecticide solution VIIA killed 60% of the exposed cockroaches after 15 days, despite a vigorous water treatment after 11 days. The residue still killed 20% of the exposed cockroaches after 18 days, despite another water treatment after 16 days.

A solution containing 50 weight-% non-volatiles was prepared as follows:

10 g. tetraethyl orthosilicate (ES-100)

40 g. dimethylpolysiloxane F1-3563 (3 wt-% OH)

0.025 g. stannous octoate

50 g. perchloroethylene

The silicate-polysiloxane solution was mixed with a pyrethroid composition to yield an insecticide-containing solution which was compared with an additive-free pyrethroid composition for insecticidal behavior. The components of the test compositions were as follows:

The insecticidal properties of solutions VIIIA and VIIIB were evaluated using adult cockroaches as the test species and glass as the test surface, as described in Example V. The treated glass panels were exposed, in duplicate, to cockroaches after 1, 3, 7 and 10 days.

The percent mortality of cockroaches exposed to the treated glass panels is summarized below:

The residue from the control insecticide solution VIIIB was ineffective after 7 days while the residue from insecticide solution VIIIA, containing the siicate-polysiloxane composition, killed 95% of the exposed cockroaches after 7 days and 65% after 10 days.

On the 11th day the panel containing the residue from solution VIIIA was subjected to treatment with water in a Waring Blender for 5 min., as described in Example I, and then reexposed to cockroaches after a total residue age of 15 days. On the 16th day the panel was again subjected to treatment with water and then reexposed to cockroaches after a total residue age of 18 days.

The percent mortality of cockroaches exposed to the treated glass panels is summarized below:

The residue from insecticide solutin VIIIA killed 40% of the exposed cockroaches after 15 days, despite a vigorous water treatment after 11 days. The residue still killed 10% of the exposed cockroaches after 18 days, despite another water treatment after 16 days.

The tetraethyl orthosilicate (ES-100)--dimethylpolysiloxane Fl-3563--stannous octoate solution of Example VIII was mixed with a pyrethroid composition to yield the following test compositions:

The insecticidal properties of solutions IXA and IXB were evaluated using adult cockroaches as the test species and glass as the test surface, as described in Example V. The treated glass panels were exposed, in duplicate, to cockroaches after 1, 3, 7 and 10 days. On the 11th day the panel containing the residue from solution IXA was subjected to treatment with water in a Waring Blender for 5 min., as described in Example I and then reexposed to cockroaches after a total residue age of 14 days.

The percent mortality of cockroaches exposed to the treated glass panels is summarized below.

The residue from the control insecticide solution IXB was ineffective on the 7th day while the residue from insecticide solution IXA, containing the silicate-polysiloxane composition, killed 75% of the exposed cockroaches after 7 days and 75% after 10 days. Even after a vigorous water treatment on the 11th day, the residue from solution IXA still killed cockroaches after 14 days.

A solution containing 50 weight-% non-volatiles was prepared as follows:

10 g. methyltriethoxysilane (A-162)

20 g. dimethylpolysiloxane Fl-3563 (3 wt-% OH)

30 g. perchloroethylene

The alkoxysilane-polysiloxane solution was mixed with a pyrethroid composition to yield an insecticide-containing solution which was compared with an additive-free pyrethroid composition for insecticidal behavior. The components of the test compositions were as follows:

The insecticidal properties of solutions XA and XB were evaluated using adult cockroaches as the test species and glass as the test surface, as described in Example V. The treated glass panels were exposed, in duplicate, to cockroaches after 1, 3, 7, 10 and 13 days.

The percent mortality of cockroaches exposed to the treated glass panels is summarized below:

The residue from control insecticide solution XB was ineffective on the 7th day while the residue from insecticide solution XA, containing the alkoxysxilane-dimethylpolysiloxane composition, killed 75% of the exposed cockroaches after 7 days, 70% after 10 days and still had some insecticidal activity after 13 days.

A solution containing 50 weight-% non-volatiles was prepared as follows:

10 g. tetraethyl orthosilicate (ES-100)

10 g. dimethylpolysiloxane Fl-3563 (3 wt-% OH)

10 g. DC-200/1000 dimethylpolysiloxane fluid

30 g. perchloroethylene

The silicate-hydroxyl containing polysiloxane-polysiloxane fluid solution was mixed with a pyrethroid composition to yield an insecticide-containing solution which was compared with an additive-free pyrethroid composition for insecticidal behavoir. The components of the test compositions were as follows:

The insecticidal properties of solutions XIA and XIB were evaluated using adult cockroaches as the test species and glass as the test surface, as described in Example V. The treated glass panels were exposed, in duplicate, to cockroaches after 1, 3, 7, 10 and 21 days.

The percent mortality of cockroaches exposed to the treated glass panels is summarized below:

The residue from the control insecticide solution XIB was ineffective on the 7th day while the residue from insecticide solution XIA, containing the silicate-hydroxyl containing polysiloxane-dimethylpolysiloxane fluid composition, killed 55% of the exposed cockroaches after 7 days, 50% after 10 days and 20% after 21 days.