阅读说明：本技术 一种耐烧蚀碳硼烷有机硅聚合物及其制备方法与应用 (Ablation-resistant carborane organic silicon polymer and preparation method and application thereof ) 是由 宋育杰 赵丽华 王毕杰 何流 黄庆 黄政仁 于 2021-01-21 设计创作，主要内容包括：本发明公开了一种耐烧蚀碳硼烷有机硅聚合物及其制备方法与应用。所述耐烧蚀碳硼烷有机硅聚合物具有下列的任一种结构：其中,R-1、R-2均独立选自-Si-O-、C-mH-(2m)、H、NH、CO、Ph、COO中的任意一种,R-3为以Si-O或CH-2为主要结构的重复单元,n为1～1000,m为0～10。本发发明提供的合成工艺简单,易于操作,固化温度在150℃以下；同时本发明制备的聚合物有良好的耐温性,在空气气氛下,1000℃时的残炭率最高可达95％以上；且该聚合物可同于制备陶瓷先驱体、耐高温涂层或中子辐射屏蔽材料,在航空航天、汽车、极端环境等方面有着极大的潜在应用价值。(The invention discloses an ablation-resistant carborane organic silicon polymer and a preparation method and application thereof. The ablation-resistant carborane organosilicon polymer has any one of the following structures: wherein R is 1 、R 2 Are all independently selected from-Si-O-, C m H 2m Any one of H, NH, CO, Ph and COO, R 3 Is made of Si-O or CH 2 Is a repeating unit of the main structure, n is 1-1000, and m is 0-10. The synthesis process provided by the invention is simple and easy to operate, and the curing temperature is below 150 ℃; at the same timeThe polymer prepared by the invention has good temperature resistance, and the carbon residue rate can reach more than 95% at 1000 ℃ in the air atmosphere; the polymer can be used for preparing a ceramic precursor, a high-temperature-resistant coating or a neutron radiation shielding material, and has great potential application value in the aspects of aerospace, automobiles, extreme environments and the like.)

1. An ablation resistant carborane organosilicon polymer having a structure according to any one of formulas (I) - (III):

wherein R is₁、R₂Are all independently selected from-Si-O-, C_mH_2mAny one of H, NH, CO, Ph and COO, R₃Is made of Si-O or CH₂Is a repeating unit of the main structure, n is 1-1000, and m is 0-10.

2. The ablation resistant carborane organosilicon polymer of claim 1, wherein: the ablation-resistant carborane organosilicon polymer has a crosslinked structure.

3. A process for preparing an ablation resistant carborane organosilicon polymer according to claim 1 or 2, comprising:

reacting a mixed reaction system containing carborane, an organic lithium reagent, halogenated olefin and/or chloroalkyne and a solvent to prepare carborane containing alkenyl;

and carrying out hydrosilylation reaction on the carborane containing the alkenyl and organic silicon, and curing to obtain the ablation-resistant carborane organic silicon polymer.

4. The production method according to claim 3, characterized by comprising:

under the conditions of protective atmosphere and ice bath, dissolving carborane in a solvent to form a carborane solution, then adding an organic lithium reagent, and stirring and reacting at 0-100 ℃ for 0.5-10 h to obtain a carborane lithium salt;

and adding halogenated olefin and/or chloroalkyne into the obtained carborane lithium salt at 0-10 ℃, reacting for 2 hours at 0-100 ℃, heating to 50-200 ℃, continuing to react for 0.5-10 hours, and cooling to 0-100 ℃ for reacting for 0.5-48 hours to obtain the alkenyl carborane.

5. The method according to claim 4, wherein the alkenyl group-containing carborane has a structure represented by any one of formulas (IV) to (VI):

wherein R is₁Selected from-Si-O-, C_mH_2mAny one of H, NH, CO, Ph and COO, wherein n is 1-1000;

and/or the carborane comprises any one or a combination of more than two of o-carborane, m-carborane and p-carborane;

and/or, the organolithium reagent comprises n-butyllithium and/or t-butyllithium;

and/or the solvent comprises one or the combination of more than two of anhydrous ether, tetrahydrofuran, toluene and xylene;

and/or the halogenated olefin and/or chloroalkyne comprises any one or a combination of more than two of bromopropene, chloropropene, bromobutene and 3-bromopropyne;

and/or the molar ratio of the carborane, the organolithium reagent and the halogenated alkene and/or chloroalkyne is 1: 0.5-3: 0.5 to 5.

6. The production method according to claim 3, characterized by comprising:

and (2) carrying out hydrosilylation reaction on the carborane containing the alkenyl and organic silicon at the temperature of 0-300 ℃ for 0.5-48 h under the action of a catalyst to obtain the ablation-resistant carborane organic silicon polymer.

7. The method according to claim 6, wherein the organosilicon has a structure represented by formula (VII):

wherein R is₂Selected from-Si-O-, C_mH_2mAny one of H, NH, CO, Ph and COO, R₃Is O and/or CH₂X is 1-1000, m is 0-10;

and/or the organosilicon comprises chain siloxanes and/or cyclic siloxanes;

and/or the organic silicon comprises any one or the combination of more than two of 1,3,5, 7-tetramethyl-1, 3,5, 7-tetravinyl cyclotetrasiloxane, 1,3,5, 7-tetramethylcyclotetrasiloxane, hydrogen-containing silicone oil and polyvinyl hydrogen-containing silicone oil;

and/or the catalyst comprises any one or the combination of more than two of a Karster catalyst, chloroplatinic acid and an organic peroxide catalyst;

and/or the molar ratio of Si-H bonds in the alkenyl-containing carborane to C ═ C bonds in the organosilicon is 100: 1-1: 100.

8. The production method according to claim 3, wherein the curing treatment includes: curing the obtained hydrosilation reaction product at 0-100 ℃ for 0.5-10 h, and then curing at 100-150 ℃ for 0.5-48 h.

9. Use of the ablation resistant carborane silicone polymer of claim 1 or 2 in aerospace, automotive or extreme environmental fields; preferably for the preparation of ceramic precursors, high temperature resistant coatings or neutron radiation shielding materials.

10. A high temperature resistant coating comprising the ablation resistant carborane silicone polymer of claim 1 or 2.

Technical Field

The invention belongs to the technical field of high polymer materials, and particularly relates to an ablation-resistant carborane organic silicon polymer and a preparation method and application thereof.

Background

The organic silicon polymer is a typical semi-inorganic high molecular material which takes a repeated (-Si-O-Si-) bond as a main chain and directly connects an organic group with a silicon atom, so that polysiloxane has organic and inorganic characteristics, but the temperature resistance of pure organic silicon cannot meet the development requirement of modern industry, and therefore, the temperature resistance of organic silicon needs to be improved by adopting a modification method.

The carborane has a high electron deficiency structure, so that the adjacent bond length of the carborane is shorter, and the carborane and the derivatives thereof have good heat resistance and oxidation resistance stability and have extremely high potential application value in a thermal protection material system; and as the CH group of the carborane is weakly acidic and is easy to react with a strongly basic organic lithium reagent to obtain a nucleophile, and the nucleophile is easy to react with the electrophile, a substitution reaction can be carried out on carbon and boron atoms without complex group protection reaction, the cage structure of the carborane is not damaged, and an effective way is provided for introducing the carborane into a polymer.

Since the sixties of the last century, the research on the carborane in the aspects of improving the high temperature resistance, ablation resistance, oxidation resistance, flame retardance and the like of the resin is started. However, most of the existing reported researches are limited to the preparation of chain polymers, and the preparation process of cross-linked polymers is complex and the curing conditions are high.

Disclosure of Invention

The invention mainly aims to provide an ablation-resistant carborane organic silicon polymer, and a preparation method and application thereof, so as to overcome the defects of the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

embodiments of the present invention provide an ablation-resistant carborane organosilicon polymer having a structure as shown in any one of formulas (I) - (iii):

wherein R is₁、R₂Are all independently selected from-Si-O-, C_mH_2mAny one of H, NH, CO, Ph and COO, R₃Is made of Si-O or CH₂Is a repeating unit of the main structure, n is 1-1000, and m is 0-10.

Further, the curves in the structures represented by formulas (I) to (III) represent the extension of the structure to form a crosslinked network structure.

The embodiment of the invention also provides a preparation method of the ablation-resistant carborane organic silicon polymer, which comprises the following steps:

reacting a mixed reaction system containing carborane, an organic lithium reagent, halogenated olefin and a solvent to prepare carborane containing alkenyl;

and carrying out hydrosilylation reaction on the carborane containing the alkenyl and organic silicon, and curing to obtain the ablation-resistant carborane organic silicon polymer.

The embodiment of the invention also provides application of the ablation-resistant carborane organic silicon polymer in the fields of aerospace, automobiles or extreme environments.

Embodiments of the present invention also provide a high temperature resistant coating, which includes the ablation resistant carborane organosilicon polymer.

Compared with the prior art, the invention has the beneficial effects that:

(1) the preparation method of the ablation-resistant carborane organic silicon polymer is simple, convenient, few in steps and easy to operate; meanwhile, the method realizes low-temperature curing and reduces the curing reaction conditions;

(2) the ablation-resistant carborane organic silicon polymer prepared by the invention has good high-temperature resistance, and has higher carbon residue rate at the high temperature of 1000 ℃ in the air atmosphere, and the highest carbon residue rate can reach more than 95%;

(3) when the ablation-resistant carborane organic silicon polymer prepared by the invention is used for preparing a coating, the ablation-resistant carborane organic silicon polymer can effectively protect carbon foam and other ablation-resistant materials.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a nuclear magnetic hydrogen spectrum of propenyl-substituted orthocarborane prepared in example 1 of the present invention;

FIG. 2 is a FT-IR plot of ablation resistant carborane silicone polymer 1 prepared in example 4 of the present invention;

FIG. 3 is a TG plot of ablation resistant carborane silicone polymer 1 prepared in example 4 of the present invention;

FIG. 4 is a FT-IR plot of ablation resistant carborane silicone polymer 2 prepared in example 5 of the present invention;

FIG. 5 is a TG plot of ablation resistant carborane silicone polymer 2 prepared in example 5 of the present invention;

FIGS. 6a-6b are pictures of a carbon foam coated with ablation resistant carborane silicone polymer 2 prepared in example 5 of the present invention before and after ablation, respectively.

Detailed Description

In view of the defects of the prior art, the inventors of the present invention have made extensive studies and practice to provide a technical solution of the present invention, which is mainly characterized in that carborane is used as a raw material, reacts with an organolithium reagent to generate a carborane lithium salt, then reacts with an electrophile containing olefin to generate carborane containing an unsaturated bond, and then reacts with organosilicon to generate a polymer after hydrosilylation reaction and curing.

The technical solutions of the present invention will be described clearly and completely below, and it should be apparent that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

One aspect of an embodiment of the present invention provides an ablation resistant carborane organosilicon polymer having a structure as shown in any one of formulas (I) - (III):

wherein R is₁、R₂Are all independently selected from-Si-O-, C_mH_2mAny one of H, NH, CO, Ph and COO, R₃Is made of Si-O or CH₂Is a repeating unit of a main structure, n is 1-1000, m is 0-10, and curves in the structures shown in formulas (I) - (III) represent that the structures have extension to form a cross-linked network structure.

Further, the ablation-resistant carborane organosilicon polymer has a cross-linked structure.

In another aspect of the embodiments of the present invention, there is provided a method for preparing the foregoing ablation-resistant carborane organosilicon polymer, which includes:

reacting a mixed reaction system containing carborane, an organic lithium reagent, halogenated olefin and/or chloroalkyne and a solvent to prepare carborane containing alkenyl;

and carrying out hydrosilylation reaction on the carborane containing the alkenyl and organic silicon, and curing to obtain the ablation-resistant carborane organic silicon polymer.

In some more specific embodiments, the preparation method comprises:

under the conditions of protective atmosphere and ice bath, dissolving carborane in a solvent to form a carborane solution, then adding an organic lithium reagent, and stirring and reacting at 0-100 ℃ for 0.5-10 h to obtain a carborane lithium salt;

and adding halogenated olefin and/or chloroalkyne into the obtained carborane lithium salt at 0-10 ℃, reacting for 2 hours at 0-100 ℃, heating to 50-200 ℃, continuing to react for 0.5-10 hours, and cooling to 0-100 ℃ for reacting for 0.5-48 hours to obtain the alkenyl carborane. Further, the alkenyl-containing carborane has a structure as shown in any one of formulas (IV) to (VI):

wherein R is₁Selected from-Si-O-, C_mH_2mAnd any one of H, NH, CO, Ph and COO, wherein n is 1-1000.

Further, the carborane includes any one or a combination of two or more of o-carborane, m-carborane and p-carborane, and is not limited thereto.

Further, the organolithium reagent includes any one or a combination of two of n-butyllithium and t-butyllithium, and is not limited thereto.

Further, the solvent includes one or a combination of two or more of anhydrous ether, tetrahydrofuran, toluene and xylene, and is not limited thereto.

Further, the halogenated olefin and/or chloroalkyne includes any one or a combination of two or more of bromopropene, chloropropene, bromobutene and 3-bromopropyne, and is not limited thereto.

Further, the molar ratio of the carborane, the organolithium reagent and the halogenated alkene and/or chloroalkyne is 1: 0.5-3: 0.5 to 5.

In some more specific embodiments, the preparation method comprises:

and (2) carrying out hydrosilylation reaction on the carborane containing the alkenyl and organic silicon at the temperature of 0-300 ℃ for 0.5-48 h under the action of a catalyst to obtain the ablation-resistant carborane organic silicon polymer.

Further, the organic silicon has a structure shown as a formula (VII):

wherein R is₂Selected from-Si-O-, C_mH_2mAny one of H, NH, CO, Ph and COO, R₃Is O and/or CH₂X is 1-1000, m is 0-10;

further, the silicone includes any one of chain siloxanes and cyclic siloxanes or a combination of two of them, and is not limited thereto.

Further, the silicone includes any one or a combination of two or more of 1,3,5, 7-tetramethyl-1, 3,5, 7-tetravinyl cyclotetrasiloxane, 1,3,5, 7-tetramethylcyclotetrasiloxane (D4H cyclotetrasiloxane), hydrogen-containing silicone oil, and polyvinyl hydrogen-containing silicone oil, but is not limited thereto.

Further, the catalyst includes any one or a combination of two or more of a kast catalyst, chloroplatinic acid, and an organic peroxide catalyst, and is not limited thereto.

Further, the molar ratio of Si-H bonds in the alkenyl-containing carborane to C ═ C bonds in the organosilicon is 100:1 to 1: 100.

Further, the curing process includes: curing the obtained hydrosilation reaction product at 0-100 ℃ for 0.5-10 h, and then curing at 100-150 ℃ for 0.5-48 h.

In some more specific embodiments, the reaction formula of the ablation resistant carborane organosilicon polymer is shown as follows (using meta-carborane as a raw material):

wherein R is₁、R₂Are all independently selected from-Si-O-, C_mH_2m、HAny one of NH, CO, Ph and COO, R₃Is Si-O or CH₂Is a repeating unit of the main structure, n is 1-1000, and m is 0-10.

Another aspect of an embodiment of the present invention also provides the use of the foregoing ablation resistant carborane silicone polymer in aerospace, automotive or extreme environmental fields.

Further, the ablation-resistant carborane organic silicon polymer can be used for preparing a ceramic precursor, a high-temperature-resistant coating or a neutron radiation shielding material.

Yet another aspect of an embodiment of the present invention provides a high temperature resistant coating comprising the foregoing ablation resistant carborane organosilicon polymer.

The technical solutions of the present invention are further described in detail below with reference to several preferred embodiments and the accompanying drawings, which are implemented on the premise of the technical solutions of the present invention, and a detailed implementation manner and a specific operation process are provided, but the scope of the present invention is not limited to the following embodiments.

The experimental materials used in the examples used below were all available from conventional biochemical reagents companies, unless otherwise specified.

Example 1: synthesis of propenyl substituted ortho carborane

Adding 100ml of anhydrous ether serving as a solvent into a three-neck flask with 500ml of stirring magneton, and adding 30g (208.02mmol) of ortho-carborane under the protection of argon in an ice bath to completely dissolve the ortho-carborane in the anhydrous ether; 167ml (417.5mmol, about 3 s.a drop) of n-butyllithium are then added dropwise slowly and continuously, after which the ice bath is removed and stirring is continued at 20 ℃ for 2 h; cooling to 0 ℃ in an ice bath again, dropwise adding 50ml (71.14g, 588mmol) of bromopropylene, heating to 50 ℃ for reflux reaction for 10 hours, then heating to 80 ℃ for reflux for 2 hours, and cooling to 50 ℃ again for reflux reaction for 24 hours; naturally cooling the reaction to room temperature the next day, and adding 50ml of deionized water to quench the reaction; filtering and rotary evaporating to obtain target product, purifying with silica gel column chromatography to obtain pure product as white transparent liquid with yield of 35.6g, and eluting with n-hexane to obtain propenyl substituted ortho-carborane, i.e. 1, 7-dipropenyl carborane (nuclear magnetic hydrogen spectrum is shown in figure 1).

Example 2: synthesis of propenyl substituted meta-carborane

Adding 100ml tetrahydrofuran as solvent into a three-neck flask with 500ml stirring magnetons, and adding 30g (208.02mmol) of m-carborane under the protection of argon in an ice bath to completely dissolve the m-carborane in the solvent; 167ml (417.5mmol, about 3 s.a drop) of tert-butyllithium are then added dropwise slowly and continuously, after which the ice bath is removed and stirring is continued at 0 ℃ for 10 h; then dropwise adding 50ml (71.14g, 588mmol) of chloropropene at 5 ℃, heating to 100 ℃, refluxing for reaction for 2h, then heating to 200 ℃, refluxing for 0.5h, and cooling to 100 ℃ again, and refluxing for 0.5 h; naturally cooling the reaction to room temperature the next day, and adding 50ml of deionized water to quench the reaction; filtering and rotary evaporating to obtain a target product after the reaction is finished, purifying by using a silica gel chromatographic column to obtain a pure product which is white transparent liquid, and selecting normal hexane as an eluent with the yield of 41.1g to prepare the propenyl substituted meta-carborane.

Example 3: synthesis of butenyl substituted para-carborane

Adding 100ml of toluene serving as a solvent into a three-neck flask with 500ml of stirring magnetons, and adding 30g (208.02mmol) of para-carborane under the protection of ice bath and argon to completely dissolve the para-carborane in the solvent; 167ml (417.5mmol, about 3 s.a drop) of n-butyllithium are then added dropwise slowly and continuously, after which the ice bath is removed and stirring is continued at 100 ℃ for 0.5 h; cooling to 10 ℃ in an ice bath again, dropwise adding 50ml (71.14g, 588mmol) of bromobutene at 0 ℃ for reflux reaction for 2h, then heating to 100 ℃ for reflux for 5h, and cooling to 50 ℃ again for reflux for 10 h; naturally cooling the reaction to room temperature the next day, and adding 50ml of deionized water to quench the reaction; and after the reaction is finished, filtering, carrying out rotary evaporation to obtain a target product, purifying by using a silica gel layer chromatographic column to obtain a pure product which is white transparent liquid, and selecting normal hexane as an eluant with the yield of 35.2g to prepare the butenyl substituted para-carborane.

Example 4

The double bond in the propenyl-substituted meta-carborane prepared in example 2 was substituted for the moiety 1,3,5, 7-tetramethyl-1, 3,5, 7-tetravinylcyclotetrasiloxane (D)₄ ^V) With 1,3,5, 7-tetramethylcyclotetrasiloxane (D)₄ ^H) Co-reaction of. According to experience, D₄ ^HAnd D₄ ^VThe molar ratio of (A) to (B) is 1.43:1, the best state is a crosslinked state, and D is reduced by 5-25% in the compounding ratio₄ ^VThe dosage is 10 to 50 percent of propenyl substituted meta-carborane in the same ratio for substitution; the catalyst is Karster catalyst with the weight fraction of D₄ ^V0.2% of. To reduce D by 15%₄ ^VWeighing the raw materials in proportion, wherein D₄ ^H 0.5g、D₄ ^V0.425g of propenyl substituted meta-carborane 0.0978g, putting the allyl substituted meta-carborane into a glass bottle with a stirring magneton, stirring the mixture for 4 hours at normal temperature, and putting the mixture into an oven for curing, wherein the curing comprises the following steps: treating at 40 deg.C for 4 h; the mixture is treated for 4 hours at 120 ℃ to obtain the ablation-resistant carborane organic silicon polymer 1 (an FT-IR diagram is shown in figure 2).

The thermal performance of the ablation-resistant carborane organic silicon polymer 1 prepared by the method is greatly improved, a TG picture is shown in figure 3, the carbon residue rate is 88.53% at 1000 ℃ in the air atmosphere, compared with a carborane-free sample, the ablation-resistant carborane organic silicon polymer has the advantages that the carbon residue rate is improved by 8.12%, and the temperature is improved when the thermal weight loss is 5%.

Example 5

The propenyl-substituted meta-carborane prepared in example 2 was reacted with 1,3,5, 7-tetramethylcyclotetrasiloxane (D)₄ ^H) Hydrosilation occurs to replace the double bond in the meta-carborane with D according to the propenyl₄ ^HDifferent structures of the polymer can be designed by different proportions of the medium silicon hydrogen bond; the raw materials are weighed according to the mixture ratio of Si-H, C-1: 1, wherein D is₄ ^H0.35g, 0.6530g of propenyl substituted meta-carborane and 20 mu L of Karster catalyst, putting the obtained product into a glass bottle with a stirring magneton, reacting for 48 hours at 0 ℃, and putting the obtained product into an oven for curing, wherein the curing treatment comprises the following steps: the mixture is treated at 0 ℃ for 10h and 100 ℃ for 48h to obtain the ablation-resistant carborane organic silicon polymer 2 (an FT-IR diagram is shown in figure 4).

The thermal performance of the ablation-resistant carborane organic silicon polymer 2 prepared by the method is greatly improved, a TG picture is shown in figure 5, the carbon residue rate reaches 93.93% at 1000 ℃ in the air atmosphere, and the temperature is about 600 ℃ when the thermal weight loss is 5%.

Example 6

The propenyl substituted meta-carborane prepared in example 2 and hydrogen-containing silicone oil are subjected to hydrosilylation, raw materials are weighed according to the proportion of Si-H, C-10: 1, wherein 0.20g of hydrogen-containing silicone oil, 0.037g of propenyl substituted meta-carborane and 10 mu L of Kaster catalyst are put into a glass bottle with a stirring magneton, the reaction is carried out for 0.5H, and the glass bottle is put into an oven for curing treatment, wherein the curing treatment comprises the following steps: treating at 100 deg.C for 0.5 h; and (3) treating at 150 ℃ for 0.5h to obtain the ablation-resistant carborane organic silicon polymer 3.

The thermal performance of the ablation-resistant carborane organic silicon polymer 3 prepared by the method is greatly improved, the carbon residue rate reaches 96% at 1000 ℃ in the air atmosphere, and the temperature is 621 ℃ when the thermal weight loss is 5%.

And (3) performance characterization:

the sample (ablation-resistant carborane organic silicon polymer 2) in example 5 is prepared into a 10 wt% sample solution by using a chain structure ratio and tetrahydrofuran as a solvent, carbon foam is placed into the solution to be fully stirred, the solution is soaked for 10 hours, then the solvent is removed, the carbon foam is cured for 4 hours at 100 ℃, and then the carbon foam is ablated for 60 to 80 seconds under the flame of a spray gun at 1300 ℃, wherein the shape and the size of the carbon foam are not substantially changed (a comparison graph before and after ablation is shown in fig. 6a and fig. 6 b).

In addition, the inventors of the present invention have also made experiments with other materials, process operations, and process conditions described in the present specification with reference to the above examples, and have obtained preferable results.

The aspects, embodiments, features and examples of the present invention should be considered as illustrative in all respects and not intended to be limiting of the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

The use of headings and chapters in this disclosure is not meant to limit the disclosure; each section may apply to any aspect, embodiment, or feature of the disclosure.

Throughout this specification, where a composition is described as having, containing, or comprising specific components or where a process is described as having, containing, or comprising specific process steps, it is contemplated that the composition of the present teachings also consist essentially of, or consist of, the recited components, and the process of the present teachings also consist essentially of, or consist of, the recited process steps.

It should be understood that the order of steps or the order in which particular actions are performed is not critical, so long as the teachings of the invention remain operable. Further, two or more steps or actions may be performed simultaneously.

While the invention has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions and/or additions may be made and substantial equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.