Abstract:
An effective method for gelling certain organic liquids. The invention, in one embodiment, comprises forming a solution of the organic liquids and an amount of a triblock copolymer of relatively moderate molecular weight, having poly(4-vinylpyridene) end blocks and a small amount of a salt of a transition metal. In another embodiment, the invention comprises forming a solution of the organic liquids and an amount of a triblock copolymer of relatively moderate molecular weight, having poly(4-vinylpyridene) end blocks and a small amount of an acid. Such gelled liquids are useful as pipe line pigs, in automobile lacquers and in charcoal lighter fluids.

Description:
This application is a continuation in part of copending applications Ser. No. 043,385, filed Apr. 28, 1987, now abandoned and Ser. No. 043,386, filed Apr. 28, 1987 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to the gelation or viscosification of organic liquids. More specifically, this invention relates to the gelation of organic liquids using ABA triblock polymers. 
     There are quite diverse applications for thickened or gelled solutions of polymers in organic liquids, potential applications for this process and the products derived therefrom will be evident in the instant application. Of particular interest, are the applications of the gelled organic liquids as pipe line pigs, automotive lacquers, and charcoal lighter fluids. 
     There are a number of physical and chemical techniques for preparing such systems. A formation of such gels, however, has usually required difficult compounding conditions. The gelling of organic liquids is normally achieved by the addition of moderate amounts of high molecular weight polymers. The degree of gelation is dependent on the level of polymer additive as well as the polymer molecular weight. As a consequence, the achievement of high viscosity via this approach requires either very high levels of additive or extremely high molecular weights of the additive component. High levels of additive are often uneconomical and they undesirably increase the viscosity and substantially decrease the number of uses for the liquid; the use of very high molecular weight additives gives rise to shear degradation which means that viscosities obtained are often unstable. 
     Accordingly, an object of this invention is to provide improved gelled organic compositions, which do not have the process limitations of compositions containing high molecular weight additives. 
     A further object of this invention is to provide a method for economically producing gelled organic compositions from readily available materials. 
     Other aspects, objects, as well as the several advantages of this invention will be apparent to those skilled in art upon reading the specification and the appended claims. 
     SUMMARY OF THE INVENTION 
     These benefits and other advantages are achieved in accordance with the present invention. In one embodiment, the present invention takes the form of a method for the gelation of organic liquids comprising: (a) providing an organic liquid having a solubility parameter in the range of between about 7.5 to about 10.5; (b) contacting the organic liquid with one or more types of ABA block polymer of moderate molecular weight, wherein the A block is 4-vinylpyridine and B block comprises a polymer having a solubility parameter such that each ABA block polymer dissolves in the organic liquid; and (c) contacting the organic liquid with at least one gelation agent in an amount effective to cause visible gelation of the organic liquid, said gelation agent being a transition metal salt or an acid. 
     In another embodiment, the invention takes the form of a composition comprising a gelled organic liquid which comprises (a) an organic liquid having a solubility parameter in the range of between about 7.5 to about 10.5; (b) one or more types of ABA block polymer of moderate molecular weight, wherein the A block is 4-vinylpyridine and B block comprises a polymer having a solubility parameter such that each ABA block polymer dissolves in the organic liquid; and (c) at least one gelation agent in an amount sufficient to form a visible gel, said gelation agent being a transition metal salt or an acid. 
     DETAILED DESCRIPTION OF THE INVENTION 
     It has been found that, surprisingly, an organic liquid having a solubility parameter between about 7.5 to about 10.5 may be gelled by adding thereto at least one type of triblock polymer of moderate molecular weight and a minor portion of at least one gelation agent. The gelation agent is a metal cation salt or an acid. 
     The gelled composition of the present invention is made up by preparing a solution of one or more types of ABA block polymer in an organic liquid. A soluble salt of a transition metal is also added to the organic liquid in an amount sufficient to cause visible gelation of the liquid. The gel state can be distinguished from the state of a macromolecular solution with critical or supercritical concentration by the fact that the polymer coils no longer move as units and can no longer interchange their places. 
     Generally, organic liquids with solubility parameters in the range from about 7.5 up to about 10.5 can be gelled. &#34;Solubility parameter&#34; (s.p.) governs the heat of mixing of liquids and amorphous polymers. Methods of calculating solubility parameters of solvents from physical constants and of polymers from experimental determinations are well-known to those skilled in the art. A general description of methods suitable for obtaining solubility parameters for solvents and polymers, and a compilation of solubility parameters for selected solvents and polymers is is set forth in the Polymer Handbook, 2nd edition, (1975) p. IV-(337-359). 
     Of the suitable organic liquids, those which are most highly polar demonstrate superior gelation. For the purposes of this invention, organic liquids which can be gelled are hydrocarbons including aliphatic (e.g., nonane and the like) or aromatic (e.g., ethylbenzene and the like); chlorinated solvents (e.g., methylchloroform and o-dichlorobenzene and the like ); ketones (e.g., methyl i-butyl ketone and the like); esters (e.g., ethyl benzoate and the like); and ethers (e.g., glyme and tetrahydrofuran and the like). Because of their relatively high solubility parameters, ethyl benzoate and o-dichlorobenzene are particularly gellable. 
     According to the present invention, organic liquids can be gelled with relatively minor amounts of at least one type of ABA triblock polymer having relatively low molecular weight. The total amount of triblock polymer added to the organic liquid is generally from about 0.5 to about 5 weight percent, based on the resultant gelled solution. Preferably, the total amount of triblock polymer comprises about 1 to about 2 weight percent of the gelled solution. further, each triblock polymer employed should have a molecular weight of between about 200,000 to about 800,000. For the purpose of the present invention, &#34;molecular weight&#34; shall mean number average molecular weight (M n ). Methods for determining number-average molecular weight are well-known to those in the art. 
     The order in which each triblock polymer and gelation agent employed are added to the organic liquid to form solution is not, for the purposes of this invention, thermodynamically critical. However, for practical operation it is highly recommended that each ABA polymer be added to the organic liquid and dispersed therein before adding the gelation agent. Uniform distribution of each copolymer and gelation agent in the organic liquid occurs, due to the kinetics involved, in a reasonably short time when each ABA polymer is added to the organic liquid prior to the gelation agent. 
     Any convenient means of mixing the copolymeric component to achieve such as organic liquid-copolymer solution may be employed. Exemplary techniques include adding the copolymers in a solution miscible with the the polar organic liquid to be thickened. 
     The property characteristics of each triblock polymer will depend upon the combined effects of the nature of the center block; the degree of polymerization of the center block; and the mole ratio of the center block to the end blocks. 
     According to this invention, the polymeric end, or A, blocks must be poly(4-vinylpyridine). The solubility parameter of poly(4-vinylpyridine) is about 10.5. In general, suitable monomers are those which may be polymerized to form center, or B, block having a solubility parameter such that the ABA triblock polymer dissolves in the organic liquid. Consequently, the solubility parameter of the B block should be between about 7.5 to about 10.5. 
     The B block comprises a polymer having a solubility parameter such that each ABA block polymer dissolves in the organic liquid. 
     Exemplary monomers utilized to prepare the B blocks are any of the styrenics and the dienes. Specifically, the monomers may be selected from the group consisting of t-butylstyrene (s.p. 8.1), styrene (s.p. 9.3), α-methylstyrene (s.p. 8.5), vinyltoluene (s.p. 9.1), butadiene (s.p. 7.1), isoprene (s.p. 7.4) and the like. The particularly preferred monomer is t-butylstyrene. 
     Although not critical to the practice of this invention, good results are generally obtained when the center block of each triblock polymer has a moderate degree of polymerization (DP), which is the number of monomer units in an average polymer molecule in a given sample. To avoid processing problems such as shear degradation of the gelled liquid, the DP of each of the center blocks will preferably be from about 2,000 to about 15,000. Most preferably, the degree of polymerization of the center block will be from about 4,000 to about 6,000. 
     The copolymeric mole ratio will generally be between about 20 to about 100 moles of monomer in the center block per mole of monomer in the end blocks. Preferably, the mole ratio will be between about 30 and about 50 moles of monomer in the center block per mole of the end blocks. If the mole ratio is greater than about 100, it is believed that there may be too little 4-vinylpyridine in the solution to cause effective gelation; copolymers with a mole ratio less than about 20 are generally found to be rather insoluble in many organic liquids. 
     Each triblock polymer is prepared by anionic polymerization. Anionic polymerization is well-known in the art. The Kirk-Othmer Encyclopedia of Chemical Technology, 3rd edition, (1980), sets forth a general description of the method. Such polymerization may be carried out through the conventional solution polymerization procedures. 
     Each copolymer is generally made up from monomers in solution with a solvent that is suitable for anionic polymerization. To be suitable for anionic polymerization, the solvent has generally no active protons, carbonyl groups, or halogens. For example, suitable solvents include aliphatic hydrocarbons (e.g., hexane); aromatic hydrocarbons (e.g., benzene); cycloaliphatic (e.g., cyclohexane); and ethers (e.g., glyme and tetrahydrofuran). 
     The metal cations suitable for the purpose of this invention are commonly defined as members of the transition elements (See Chemical Text: &#34;Chemical Principles and Properties&#34; by M. J. Sienko and R. A. Plane, McGraw Hill Book Co., 1974, Page 19). Preferred transition metals include palladium, iron, cobalt, and copper, with palladium being the most preferred. 
     The quantity of the gelation agent employed has a pronounced influence on the thickening that is achieve, i.e., increase in gelation of the organic liquid-copolymer solution. By &#34;effective amount&#34; of gelation agent is meant that concentration of gelation agent is sufficient to achieve visible gelation of the solution. 
     When the gelation agent is a metal ion, the concentration of metal ion is based on the total number of metal cations relative to the total number of vinylpyridene moieties on the polymer chains in the organic liquid. Generally, the concentration of metal cations will be from between about 25 moles to about 75 moles of metal cation per 100 moles of 4-vinylpyridene moieties, preferably from between about 30 moles to about 60 moles of metal cation per 100 moles of 4-vinylpyridene moieties. A maximum thickening effect is accomplished when the concentration of metal cations is about 50 moles of metal cation per 100 moles of 4-vinylpyridene moieties. Above a ratio of about 75 moles of metal cation per 100 moles of 4-vinylpyridene moieties, the invention is still operative but the thickening effect is not substantially better than the maximum effect obtainable at the specified lower concentrations. The valence state of the metal may also be an important factor. 
     When the gelation agent is an acid, the concentration of acid is based on the total number of moles of acid relative to the total number of moles of vinylpyridene moieties in the polyer chains. Generally, the acid will be present in an amount from about 35 moles of acid to about 65 moles of acid per 100 moles of 4-vinylpyridene moieties. A maximum thickening effect is accomplished when the concentration of acid is about 50 moles of acid per 100 moles of 4-vinylpyridene moieties. Above about 65 moles of acid per 100 moles of 4-vinylpyridene moieties, the composition of this invention is still operative, but the thickening effect is not substantially better than the maximum effect obtainable at the specified lower concentrations. 
     As stated above, the gelation agent should be added to the organic liquid after the copolymers to hasten uniform gelation. The gelation agent may be added to the organic liquid directly, although, due to the kinetics involved, pronounced clumping occurs and uniform gelation is substantially slowed. Therefore, for practical operations the gelation agent is preferably taken up in solvent solution, and preferably the gelation agent solution added to the organic liquid-copolymer solution. 
     When the gelation agent is a transition metal ion, the transition metal ion should be made up, then, in solution in a solvent which will dissolve in the organic, liquid. Preferably, the gelation agent will be prepared in solution with a solvent which has a very high solubility parameter; i.e., about 10; and/or which is very polar. Exemplary of solvents with solubility parameters above 10 are amides (e.g., dimethyl formamide); alcohols (methyl alcohol, and ethylene glycol); amines (e.g., ethyl amine); ethers (e.g., 1,4-dioxane); and aromatic heterocycles (e.g., pyridine). Exemplary polar solvents include tetrahydrofuran and methylene chloride. The most preferred solvent is dimethyl formamide (DMF). 
     When the gelatin agent employed is an acid the solvent will preferably be polar. Moreover, the solvent used in preparing the acid should be substantially nonaqueous. Although not intended to be bound by theory, it is believed that any water which may be present in the system will compete with the acid for protonation sides on the vinylpyridine moieties. Exemplary of suitable polar solvents include, in anhydrous form, amides (e.g., dimethyl formamide); alcohols (methyl alcohol, and ethylene glycol); amines (e.g., ethyl amine), esters (e.g., 1,4-dioxane); and aromatic heterocycles (e.g., pyridine). The most preferred solvent is dimethyl formamide (DMF). 
     Beneficially, a characteristic of gelled solutions of this invention is that of having relatively stable viscosities. Generally, the viscosity will not be reduced over relatively long time periods. The behavior of the gelled solution relative to shear, i.e., whether the solution will be shearthickening or shear-thinning, will depend upon the specific organic liquid, the triblock polymers, and gelation agent employed. The viscosity of the gelled solution is not substantially affected when the temperature is varied from between about 25° C. and 70° C. In conventional concentrated organic liquid-copolymer solutions, the viscosity drops significantly with increasing temperature. 
    
    
     The present invention is further illustrated, but not limited, by the following examples. All parts and percentages are by weight. 
     EXAMPLES 
     EXAMPLE 1 
     An ABA copolymer solution, having A blocks of 4-vinylpyridene (4-VP) and a B block of t-butylstyrene (t-BS) is prepared. The degree of polymerization of each of the center blocks is about 2280. The mole ratio of tBS/VP is 96.5. 
     The triblock polymer solution is added to o-dichlorobenzene, an organic liquid with a solubility parameter of 10.04, in such a quantity to prepare an organic liquid-copolymer solution having about 1 percent copolymer based on the volume of the liquid. Enough solution by volume is weighed into small vials to provide 1.5-gram portions of said solution. 
     Solutions each containing about one percent of a transition metal, with the exception of technetium (Tc), based on the volume of the liquid are prepared in DMF. In each of a series of tests three drops of the metal salt solution is added to a polymer solution. The copolymer solution in each case is warmed in a steam bath to assure complete dissolution of the salt and uniform distribution of the gel. 
     The solutions are allowed to cool and checked for the extent of gelation. 
     Results of the Example 1 are summarized in Table 1. 
     
                                           TABLE 1__________________________________________________________________________Extent of gelation of o-diClBz with Various 1% (w/v) ABATriblock Polymer-Transition Metal Salt Combinations__________________________________________________________________________Metal Ion  ScCl.sub.3.6H.sub.2 O           TiCl.sub.3                 VCl.sub.3                      CrCl.sub.3.6H.sub.2 O                              MnCl.sub.2.4H.sub.2 OGel State  NE       FLW   sFLW NE      sFLWMetal Ion  Y(NO.sub.3).sub.2.6H.sub.2 O           ZrCl.sub.4                 NbCl.sub.5                      MoCl.sub.5                              TcGel State       FLW   FLW  FLPMetal Ion  LaCl.sub.3.6H.sub.2 O           HfCl.sub.4                 TaCl.sub.5                      WCl.sub.6                              ReCl.sub.3Gel State  NE       FLP   FLP  FLW     FLP__________________________________________________________________________Metal Ion FeCl.sub.3.6H.sub.2 O        CoCl.sub.3.6H.sub.2 O               NiCl.sub.3.6H.sub.2 O                      CuCl.sub.3.2H.sub.2 O                             Zn(OAc).sub.2.2H.sub.2 OGel State sFLW   sFLW   sFLW   FLW    NEMetal Ion RuCl.sub.3.3H.sub.2 O        RhCl.sub.5.3H.sub.2 O               PdCl.sub.2                      AgNO.sub.3                             Cd(NO.sub.3).sub.2.4H.sub.2 OGel State sFLW   sFLW   STF    FLW    FLWMetal Ion OsCl.sub.3        IrCl.sub.3.3H.sub.2 O               PtCl.sub.2                      AuCl.sub.3.6H.sub.2 O                             HgCl.sub.2Gel State sFLP   NE     sFLW   NE     sFLW__________________________________________________________________________ Gelation is rated as follows: NE (No effect) FLW (Flowing gel)  The solution is completely filled with loose gels whic flow freely. FLP (Floppy Gel)  The gel holds together and flops back and forth in the vial. STF (Stiff gel)  The gel does not move in the vial with light shaking. The prefix &#34;s&#34; before a rating means &#34;not quite as good&#34;. 
    
     EXAMPLE 2 
     The procedures of Example 1 are followed with the exception that the degree of polymerization of each of the center blocks is about 5200 and the mole ratio to tBS/VP is 23.3. 
     Results of the Example 2 are summarized in Table 2. 
     
                                           TABLE 2__________________________________________________________________________Extent of gelation of o-diClBz with Various 1% (w/v) ABATriblock Polymer-Transition Metal Salt Combinations__________________________________________________________________________Metal Ion  ScCl.sub.3.6H.sub.2 O           TiCl.sub.3                 VCl.sub.3                      CrCl.sub.3.6H.sub.2 O                              MnCl.sub.2.4H.sub.2 OGel State  sFLP     sFLP  sFLP sFLP    sFLPMetal Ion  Y(NO.sub.3).sub.2.6H.sub.2           ZrCl.sub.4                 NbCl.sub.5                      MoCl.sub.5                              TcGel State  sFLW     sFLP  sFLP FLPMetal Ion  LaCl.sub.3.6H.sub.2 O           HfCl.sub.4                 TaCl.sub.5                      WCl.sub.6                              ReCl.sub.3Gel State  sFLW     FLP   FLP  FLP     FLP__________________________________________________________________________Metal Ion FeCl.sub.3.6H.sub.2 O        CoCl.sub.3.6H.sub.2 O               NiCl.sub.3.6H.sub.2 O                      CuCl.sub.3.2H.sub.2 O                             Zn(OAc).sub.2.2H.sub.2 OGel State sFLP   STF    FLP    FLP    FLPMetal Ion RuCl.sub.3.3H.sub.2 O        RhCl.sub.5.3H.sub.2 O               PdCl.sub.2                      AgNO.sub.3                             Cd(NO.sub.3).sub.2.4H.sub.2 OGel State FLW    STF    STF    FLW    FLPMetal Ion OsCl.sub.3        IrCl.sub.3.3H.sub.2 O               PtCl.sub.2                      AuCl.sub.3.6H.sub.2 O                             HgCl.sub.2Gel State FLP    FLW    FLW    FLW    FLP__________________________________________________________________________ Gelation is rated as follows: NE (No effect) FLW (Flowing gel)  The solution is completely filled with loose gels whic flow freely. FLP (Floppy Gel)  The gel holds together and flops back and forth in the vial. STF (Stiff gel)  The gel does not move in the vial with light shaking. The prefix &#34;s&#34; before a rating means &#34;not quite as good&#34;. 
    
     EXAMPLE 3 
     The procedures of Example 1 are followed with the exception that the degree of polymerization of each of the center blocks is about 9650 and the mole ratio of tBS/VP is 32.5. 
     Results of the Example 3 are summarized in Table 3. 
     
                                           TABLE 3__________________________________________________________________________Extent of gelation of o-diClBz with Various 1% (w/v) ABATriblock Polymer-Transition Metal Salt Combinations__________________________________________________________________________Metal Ion  ScCl.sub.3.6H.sub.2 O           TiCl.sub.3                 VCl.sub.3                      CrCl.sub.3.6H.sub.2 O                              MnCl.sub.2.4H.sub.2 OGel State  FLW      FLW   FLW  FLW     FLWMetal Ion  Y(NO.sub.3).sub.2.6H.sub.2 O           ZrCl.sub.4                 NbCl.sub.5                      MoCl.sub.5                              TcGel State  NE       FLW   FLW  FLWMetal Ion  LaCl.sub.3.6H.sub.2 O           HfCl.sub.4                 TaCl.sub.5                      WCl.sub.6                              ReCl.sub.3Gel State  NE       sFLP  sFLP FLW     sFLP__________________________________________________________________________Metal Ion FeCl.sub.3.6H.sub.2 O        CoCl.sub.3.6H.sub.2 O               NiCl.sub.3.6H.sub.2 O                      CuCl.sub.3.2H.sub.2 O                             Zn(OAc).sub.2.2H.sub.2 OGel State FLW    sFLP   FLW    FLW    sFLPMetal Ion RuCl.sub.3.3H.sub.2 O        RhCl.sub.5.3H.sub.2 O               PdCl.sub.2                      AgNO.sub.3                             Cd(NO.sub.3).sub.2.4H.sub.2 OGel State sFLP   FLP    FLP    FLW    FLWMetal Ion OsCl.sub.3        IrCl.sub.3.3H.sub.2 O               PtCl.sub.2                      AuCl.sub.3.6H.sub.2 O                             HgCl.sub.2Gel State FLW    FLP    NE     FLW    sFLP__________________________________________________________________________ Gelation is rated as follows: NE (No effect) FLW (Flowing gel)  The solution is completely filled with loose gels whic flow freely. FLP (Floppy Gel)  The gel holds together and flops back and forth in the vial. STF (Stiff gel)  The gel does not move in the vial with light shaking. The prefix &#34;s&#34; before a rating means &#34;not quite as good&#34;. 
    
     EXAMPLE 4 
     The procedures of Example 1 are utilized with the following exceptions. The degree of polymerization of each of the center blocks is about 5190 and the mole ratio of tBS/VP is 60.3. 
     The ABA triblock polymer is added to ethylbenzene, an organic liquid with a solubility parameter of 8.81, in such a quantity to prepare a solution having about 1 percent copolymer based on the volume of the liquid. 
     Results of the Example 4 are summarized in Table 4. 
     
                                           TABLE 4__________________________________________________________________________Extent of gelation of EB with Various 1% (w/v) ABATriblock Polymer-Transition Metal Salt Combinations__________________________________________________________________________Metal Ion  ScCl.sub.3.6H.sub.2 O           TiCl.sub.3                 VCl.sub.3                      CrCl.sub.3.6H.sub.2 O                              MnCl.sub.2.4H.sub.2 OGel State  sFLW     FLW   FLW  FLW     FLWMetal Ion  Y(NO.sub.3).sub.2.6H.sub.2 O           ZrCl.sub.4                 NbCl.sub.5                      MoCl.sub.5                              TcGel State  NE       FLP   FLP  FLPMetal Ion  LaCl.sub.3.6H.sub.2 O           HfCl.sub.4                 TaCl.sub.5                      WCl.sub.6                              ReCl.sub.3Gel State  NE       FLP   FLW  FLP     FLP__________________________________________________________________________Metal Ion FeCl.sub.3.6H.sub.2 O        CoCl.sub.3.6H.sub.2 O               NiCl.sub.3.6H.sub.2 O                      CuCl.sub.3.2H.sub.2 O                             Zn(OAc).sub.2.2H.sub.2 OGel State STF    STF    FLP    FLW    FLWMetal Ion RuCl.sub.3.3H.sub.2 O        RhCl.sub.5.3H.sub.2 O               PdCl.sub.2                      AgNO.sub.3                             Cd(NO.sub.3).sub.2.4H.sub.2 OGel State FLP    FLW    FLP    FLW    FLPMetal Ion OsCl.sub.3        IrCl.sub.3.3H.sub.2 O               PtCl.sub.2                      AuCl.sub.3.6H.sub.2 O                             HgCl.sub.2Gel State FLW    FLP    FLW    sFLW   FLW__________________________________________________________________________ Gelation is rated as follows: NE (No effect) FLW (Flowing gel)  The solution is completely filled with loose gels whic flow freely. FLP (Floppy Gel)  The gel holds together and flops back and forth in the vial. STF (Stiff gel)  The gel does not move in the vial with light shaking. The prefix &#34;s&#34; before a rating means &#34;not quite as good&#34;. 
    
     EXAMPLE 5 
     The procedures of Example 2 are followed with the exception that the ABA triblock polymer is added to tetrahydrofuran, an organic liquid with a solubility parameter of 9.32, in such a quantity to prepare a solution having about 1 percent copolymer based on the volume of the liquid. 
     Results of the Example 5 are summarized in Table 5. 
     
                                           TABLE 5__________________________________________________________________________Extent of gelation of THF with Various 1% (w/v) ABATriblock Polymer-Transition Metal Salt Combinations__________________________________________________________________________Metal Ion  ScCl.sub.3.6H.sub.2 O           TiCl.sub.3                 VCl.sub.3                      CrCl.sub.3.6H.sub.2 O                              MnCl.sub.2.4H.sub.2 OGel State  sFLW     STF   FLP  FLP     FLPMetal Ion  Y(NO.sub.3).sub.2.6H.sub.2 O           ZrCl.sub.4                 NbCl.sub.5                      MoCl.sub.5                              TcGel State  NE       STF   STF  FLPMetal Ion  LaCl.sub.3.6H.sub.2 O           HfCl.sub.4                 TaCl.sub.5                      WCl.sub.6                              ReCl.sub.3Gel State  sFLW     STF   STF  sFLP    STF__________________________________________________________________________Metal Ion FeCl.sub.3.6H.sub.2 O        CoCl.sub.3.6H.sub.2 O               NiCl.sub.3.6H.sub.2 O                      CuCl.sub.3.2H.sub.2 O                             Zn(OAc).sub.2.2H.sub.2 OGel State FLP    FLP    FLP    STF    sFLPMetal Ion RuCl.sub.3.3H.sub.2 O        RhCl.sub.5.3H.sub.2 O               PdCl.sub.2                      AgNO.sub.3                             Cd(NO.sub.3).sub.2.4H.sub.2 OGel State STF    STF    STF    FLW    FLPMetal Ion OsCl.sub.3        IrCl.sub.3.3H.sub.2 O               PtCl.sub.2                      AuCl.sub.3.6H.sub.2 O                             HgCl.sub.2Gel State STF    sFLW   STF    sFLW   sFLW__________________________________________________________________________ Gelation is rated as follows: NE (No effect) FLW (Flowing gel)  The solution is completely filled with loose gels whic flow freely. FLP (Floppy Gel)  The gel holds together and flops back and forth in the vial. STF (Stiff gel)  The gel does not move in the vial with light shaking. The prefix &#34;s&#34; before a rating means &#34;not quite as good&#34;. 
    
     EXAMPLE 6 
     The procedures of Example 4 are followed with the exception that the ABA triblock polymer is added to methylchloroform, an organic liquid with a solubility parameter of 8.50, in such a quantity to prepare a solution having about 1 percent copolymer based on the volume of the liquid. 
     Results of the Example 6 are summarized in Table 6. 
     
                                           TABLE 6__________________________________________________________________________Extent of gelation of MeCCl.sub.3 with Various 1% (w/v) ABATriblock Polymer-Transition Metal Salt Combinations__________________________________________________________________________Metal Ion  ScCl.sub.3.6H.sub.2 O           TiCl.sub.3                 VCl.sub.3                      CrCl.sub.3.6H.sub.2 O                              MnCl.sub.2.4H.sub.2 OGel State  sFLW     FLW   FLP  sFLP    sFLPMetal Ion  Y(NO.sub.3).sub.2.6H.sub.2 O           ZrCl.sub.4                 NbCl.sub.5                      MoCl.sub.5                              TcGel State  NE       FLP   FLW  FLWMetal Ion  LaCl.sub.3.6H.sub.2 O           HfCl.sub.4                 TaCl.sub.5                      WCl.sub.6                              ReCl.sub.3Gel State  NE       FLW   sFLP STF     FLP__________________________________________________________________________Metal Ion FeCl.sub.3.6H.sub.2 O        CoCl.sub.3.6H.sub.2 O               NiCl.sub.3.6H.sub.2 O                      CuCl.sub.3.2H.sub.2 O                             Zn(OAc).sub.2.2H.sub.2 OGel State STF    sFLP   sFLP   FLP    sFLWMetal Ion RuCl.sub.3.3H.sub.2 O        RhCl.sub.5.3H.sub.2 O               PdCl.sub.2                      AgNO.sub.3                             Cd(NO.sub.3).sub.2.4H.sub.2 OGel State FLP    FLW    FLP    FLW    sFLPMetal Ion OsCl.sub.3        IrCl.sub.3.3H.sub.2 O               PtCl.sub.2                      AuCl.sub.3.6H.sub.2 O                             HgCl.sub.2Gel State FLP    sFLP   sFLW   sFLW   sFLP__________________________________________________________________________ Gelation is rated as follows: NE (No effect) FLW (Flowing gel)  The solution is completely filled with loose gels whic flow freely. FLP (Floppy Gel)  The gel holds together and flops back and forth in the vial. STF (Stiff gel)  The gel does not move in the vial with light shaking. The prefix &#34;s&#34; before a rating means &#34;not quite as good&#34;. 
    
     EXAMPLE 7 
     The procedures of Example 1 are utilized with the following exceptions. The degree of polymerization of the each of the center blocks is about 9230 and the mole ratio of tBS/VP is 66.9. 
     The ABA triblock polymer is added to glyme, an organic liquid with a solubility parameter of 8.6, in such a quantity to prepare a solution having about 1 percent copolymer based on the volume of the liquid. 
     Results of the Example 7 are summarized in Table 7. 
     
                                           TABLE 7__________________________________________________________________________Extent of gelation of Glyme with Various 1% (w/v) ABATriblock Polymer-Transition Metal Salt Combinations__________________________________________________________________________Metal Ion  ScCl.sub.3.6H.sub.2 O           TiCl.sub.3                 VCl.sub.3                      CrCl.sub.3.6H.sub.2 O                              MnCl.sub.2.4H.sub.2 OGel State  FLW      FLW   FLW  FLP     FLWMetal Ion  Y(NO.sub.3).sub.2.6H.sub.2 O           ZrCl.sub.4                 NbCl.sub.5                      MoCl.sub.5                              TcGel State  NE       FLW   FLW  FLWMetal Ion  LaCl.sub.3.6H.sub.2 O           HfCl.sub.4                 TaCl.sub.5                      WCl.sub.6                              ReCl.sub.3Gel State  FLW      sFLP  FLW  FLW     FLW__________________________________________________________________________Metal Ion FeCl.sub.3.6H.sub.2 O        CoCl.sub.3.6H.sub.2 O               NiCl.sub.3.6H.sub.2 O                      CuCl.sub.3.2H.sub.2 O                             Zn(OAc).sub.2.2H.sub.2 OGel State FLP    sFLP   FLW    FLW    sFLPMetal Ion RuCl.sub.3.3H.sub.2 O        RhCl.sub.5.3H.sub.2 O               PdCl.sub.2                      AgNO.sub.3                             Cd(NO.sub.3).sub.2.4H.sub.2 OGel State FLP    FLP    sFLP   FLW    FLWMetal Ion OsCl.sub.3        IrCl.sub.3.3H.sub.2 O               PtCl.sub.2                      AuCl.sub.3.6H.sub.2 O                             HgCl.sub.2Gel State FLW    FLW    FLP    NE     FLW__________________________________________________________________________ Gelation is rated as follows: NE (No effect) FLW (Flowing gel)  The solution is completely filled with loose gels whic flow freely. FLP (Floppy Gel)  The gel holds together and flops back and forth in the vial. STF (Stiff gel)  The gel does not move in the vial with light shaking. The prefix &#34;s&#34; before a rating means &#34;not quite as good&#34;. 
    
     EXAMPLE 8 
     The procedures of Example 1 are utilized with the following exceptions. The degree of polymerization of each of the center blocks is about 15,860 and the mole ratio of tBS/VP is 97.9. 
     The ABA triblock polymer is added to ethyl benzoate, an organic liquid with a solubility parameter of 9.75, in such a quantity to prepare a solution having about 1 percent copolymer based on the volume of the liquid. 
     Results of the Example 8 are summarized in Table 8. 
     
                                           TABLE 8__________________________________________________________________________Extent of gelation of EtOOCΦ with Various 1% (w/v) ABATriblock Polymer-Transition Metal Salt Combinations__________________________________________________________________________Metal Ion  ScCl.sub.3.6H.sub.2 O           TiCl.sub.3                 VCl.sub.3                      CrCl.sub.3.6H.sub.2 O                              MnCl.sub.2.4H.sub.2 OGel State  sFLW     sFLP  FLW  FLW     sFLPMetal Ion  Y(NO.sub.3).sub.2.6H.sub.2 O           ZrCl.sub.4                 NbCl.sub.5                      MoCl.sub.5                              TcGel State  NE       sFLP  FLW  FLWMetal Ion  LaCl.sub.3.6H.sub.2 O           HfCl.sub.4                 TaCl.sub.5                      WCl.sub.6                              ReCl.sub.3Gel State       sFLP  FLW  FLW     FLW__________________________________________________________________________Metal Ion FeCl.sub.3.6H.sub.2 O        CoCl.sub.3.6H.sub.2 O               NiCl.sub.3.6H.sub.2 O                      CuCl.sub.3.2H.sub.2 O                             Zn(OAc).sub.2.2H.sub.2 OGel State FLW    FLW    sFLP   sFLP   sFLWMetal Ion RuCl.sub.3.3H.sub.2 O        RhCl.sub.5.3H.sub.2 O               PdCl.sub.2                      AgNO.sub.3                             Cd(NO.sub.3).sub.2.4H.sub.2 OGel State FLW    sFLP   sSTF   FLW    FLWMetal Ion OsCl.sub.3        IrCl.sub.3.3H.sub.2 O               PtCl.sub.2                      AuCl.sub.3.6H.sub.2 O                             HgCl.sub.2Gel State FLW    FLW    sFLW   sFLW   FLW__________________________________________________________________________ Gelation is rated as follows: NE (No effect) FLW (Flowing gel)  The solution is completely filled with loose gels whic flow freely. FLP (Floppy Gel)  The gel holds together and flops back and forth in the vial. STF (Stiff gel)  The gel does not move in the vial with light shaking. The prefix &#34;s&#34; before a rating means &#34;not quite as good&#34;. 
    
     EXAMPLE 9 
     An ABA copolymer solution, having A blocks of 4-vinylpyridene and a B block of t-butylstyrene is prepared. The degree of polymerization of each center block is about 9230. The mole ratio of tBS/VP is 66.9. 
     The triblock polymer solution is added to methyl i-butyl ketone (solubility parameter of 8.58) in such a quantity to prepare an organic liquid-copolymer solution having about 1 percent copolymer based on the volume of the liquid. One-gram portions of the solution are weighed into small vials. 
     A first acid solution is prepared by admixing 4.47 grams of p-toluene sulfonic acid.H 2  O in 100 ml of dimethyl formamide (DMF). The acid solution has a strength of 2.35×10 -4  mmol/μl. 
     A second acid solution is prepared by bubbling gaseous HCl into 100 ml of dimethyl formamide (DMF) until an acid solution having a strength of 2.92×10 -4  mmol/μl is obtained. 
     A third acid solution of anhydrous H 3  PO 4  is prepared by admixing 1.0 gram of anhydrous H 3  PO 4  in 50 ml of dimethyl formamide (DMF). The acid solution has a strength of 2.04×10 -4  mmol/μl. 
     A fourth acid solution of anhydrous oxalic acid is prepared by admixing 1.0 gram of anhydrous oxalic acid in 50 ml of dimethyl formamide (DMF). The acid solution has a strength of 2.22×10 -4  mmol/μl. 
     The 1.0-gram portions of the copolymer solution are admixed with 5 μl of the several different types of acids. Each portion is warmed in a steam bath to assure complete dissolution of the acid and uniform distribution of the gel. In each instance, the solutions are allowed to cool and checked for the extent of gelation. 
     Results of the Example 9 are set forth in Table 9. 
     EXAMPLE 10 
     The procedures of Example 1 are followed with the exception that the ABA triblock copolymer is added to methylchloroform (solubility parameter of 8.50) in such a quantity to prepare a copolymer solution having about 2 percent copolymer based on the volume of the liquid. 
     The 1.0-gram portions of the copolymer solution are admixed with 10 μl of the several different types of acids. 
     Results of the Example 10 are set forth in Table 9. 
     EXAMPLE 11 
     The procedures of Example 1 are followed with the exception that the ABA copolymer is added to tetrahydrofuran (solubility parameter of 9.32) in such a quantity to prepare a solution having about 0.5 percent triblock polymer based on the volume of the liquid. 
     The 1.0-gram portions of the copolymer solution are admixed with 5 μl of the several different types of acids. 
     Results of the Example 11 are set forth in Table 9. 
     EXAMPLE 12 
     The procedures of Example 1 are followed with the exception that the ABA triblock polymer is added to o-dichlorobenzene (solubility parameter of 10.04) in such a quantity to prepare a solution having about 5 percent triblock polymer based on the volume of the liquid. 
     The 1.0-gram portions of the copolymer solution are admixed with 50 μl of the several different types of acids. 
     Results of the Example 12 are set forth in Table 9. 
     
                       TABLE 9______________________________________Ex-am-             Vol Acidple  Solution   Solution pTSA  HCl   H.sub.3 PO.sub.4                                      Oxalic______________________________________ 9   1% MiBK     5 μl FLW   FLW   FLW   FLW10   2%         10 μl FLW   FLW   sFLW  STFMeCCl.sub.311   0.5% THF    5 μl FLW   FLW   FLP   NE12   5% o-DCIB  50 μl STF   STF   STF   STF______________________________________ NE (No effect) FLW (Flowing gel)  The solution is completely filled with loose gels whic flow freely. FLP (Floppy Gel)  The gel holds together and flops back and forth in the vial. STF (Stiff gel)  The gel does not move in the vial with light shaking. The prefix &#34;s&#34; before a rating means &#34;not quite as good&#34;. 
    
     EXAMPLE 13 
     The procedures of Example 1 are followed with the following exceptions: The ABA triblock polymer employed has a center block of t-butylstyrene with a degree of polymerization of about 15,860 and the mole ratio of tBS/VP is 97.9. The copolymer is added to glyme (solubility parameter of 8.6) in such a quantity to prepare a solution having about 1 percent copolymer based on the volume of the liquid. 
     The 1.0-gram portions of the copolymer solution are admixed with 5 μl of the several different types of acids. 
     Results of the Example 13 are set forth in Table 10. 
     EXAMPLE 14 
     The procedures of Example 5 are followed with the following exception: The copolymer is added to nonane (solubility parameter of 7.75) in such a quantity to prepare a solution having about 1 percent copolymer based on the volume of the liquid. 
     The 1.0-gram portions of the copolymer solution are admixed with 5 μl of the several different types of acids. Results of the Example 14 are set forth in Table 10. 
     EXAMPLE 15 
     The procedures of Example 6 are followed with the following exception: the 1.0-gram portions of the copolymer solution are admixed with 50 μl of the several different types of acids. 
     Results of the Example 15 are set forth in Table 10. 
     EXAMPLE 16 
     The procedures of Example 5 are followed with the following exception: The copolymer is added to tetrahydrofuran (solubility parameter of 9.32) in such a quantity to prepare a solution having about 3.2 percent copolymer based on the volume of the liquid. 
     The 1.0-gram portions of the polymer solution are admixed with 16 μl of the several different types of acids. 
     Results of the Example 16 are set forth in Table 10. 
     
                       TABLE 10______________________________________Ex-am-            Vol Acidple  Solution  Solution pTSA  HCl   H.sub.3 PO.sub.4                                     Oxalic______________________________________13   1% glyme   5 μl FLW   FLW   FLW   FLW14   1% C.sub.9 H.sub.20           5 μl η ↑                         η ↑                               NE    FLW15   1% C.sub.9 H.sub.20          50 μl η ↑                         sFLW  η ↑                                     sFLW16   3.2% THF  16 μl STF   STF   STF   Rubbery______________________________________ NE (No Effect) η ↑ viscosity increased FLW (Flowing gel)  The solution is completely filled with loose gels whic flow freely. Rubbery  an elastic gel formed. FLP (Floppy Gel)  The gel holds together and flops back and forth in the vial. STF (Stiff gel)  The gel does not move in the vial with light shaking. The prefix &#34;s&#34; before a rating means &#34;not quite as good&#34;. 
    
     EXAMPLE 17 
     The procedures of Example 1 are followed with the following exceptions: The ABA triblock polymer employed has a center block of t-butylstyrene with a degree of polymerization of about 5200 and the mole ratio of tBS/VP is 28.3. The copolymer is added to tetrahydrofuran (solubility parameter of 9.32) in such a quantity to prepare a solution having about 1 percent copolymer based on the volume of the liquid. 
     The 1.0-gram portions of the polymer solution are admixed with 5 μl of the several different types of acids. 
     Results of the Example 17 are set forth in Table 11. 
     EXAMPLE 18 
     The procedures of Example 9 are followed with the following exceptions: the copolymer is added to methyl i-butyl ketone (solubility parameter of 8.58) in such a quantity to prepare a solution having about 1 percent copolymer based on the volume of the liquid and the 1.0-gram portions of the polymer solution are admixed with 50 μl of the several different types of acids. 
     Results of the Example 18 are set forth in Table 11. 
     EXAMPLE 19 
     The procedures of Examples 1 are followed with the following exceptions: The ABA triblock polymer employed has a center block of styrene with a degree of polymerization of about 4080 and the mole ratio of tBS/VP is 31.0. The polymer is added to tetrahydrofuran (solubility parameter of 9.32) in such a quantity to prepare a solution having about 2 percent copolymer based on the volume of the liquid. 
     The 1.0-gram portions of the polymer solution are admixed with 100 μl of the several different types of acids. 
     Results of the Example 19 are set forth in Table 11. 
     
                       TABLE 11______________________________________Ex-am-            Vol Acidple  Solution  Solution pTSA  HCl   H.sub.3 PO.sub.4                                      Oxalic______________________________________17   1% THF     5 μl FLW   FLW   Discreet                                      NE                               gels18   1% MiBK    50 μl                   FLW   sFLW  FLW    FLW19   2% THF    100 μl                   STF   STF   STF    STF______________________________________ NE (No effect) FLW (Flowing gel)  The solution is completely filled with loose gels whic flow freely. FLP (Floppy Gel)  The gel holds together and flops back and forth in the vial. STF (Stiff gel)  The gel does not move in the vial with light shaking. The prefix &#34;s&#34; before a rating means &#34;not quite as good&#34;.