WO1996028057A9

WO1996028057A9 - Conforming shoe construction using gels and method of making the same

Info

Publication number: WO1996028057A9
Application number: PCT/US1996/003480
Authority: WO
Filing date: 1996-03-15
Publication date: 1996-12-12

Abstract

A shoe that conforms to foot contours and provides cushioning is comprised of a shoe sole and a shoe upper attached to the shoe sole. The shoe upper is comprised of an outer layer, an inner layer and a conforming layer therebetween, wherein a first portion of the conforming layer is comprised of viscoelastic gel and a second portion of the conforming layer is comprised of environmentally-responsive gel. The environmentally-responsive gel is preferably a temperature-responsive gel that will react to the heat emanating from a foot inserted into the shoe to express a liquid. The viscoelastic gel is preferably a soft, flowable gel that conforms to foot contours. The shoe may alternatively incorporate a thermally responsive polymer gel or a reversibly gelling polymer network which exhibits a dramatic change in viscosity in response to a change in environmental stimulus, such as temperature. The thermally responsive polymer gel will react to the heat generated by a foot inserted into the shoe to increase viscosity and provide the foot a measure of support.

Description

CONFORMING SHOE CONSTRUCTION USING GELS AND METHOD OF MAKING THE SAME

Technical Field This invention relates to a customized fitting shoe construction using gels and a method of forming the same. More particularly, the invention relates to a shoe that incorporates various gels to provide a conforming medium for a customized fitting shoe upper, tongue and foot bed and to methods of forming the shoe upper, tongue and foot bed.

Background of the Invention

Various methods and devices have been employed in shoes to add cushioning to the shoe and to provide complementary custom fitting configurations to the contours of a foot inserted into the shoe. For example, U.S. Patent No. 5,313,717, which issued to the present inventor, is directed to a shoe which incorporates reactive-energy, fluid-filled cavities in the shoe mid-sole. As discussed therein, typical prior art devices provide cushioning and custom fit to the foot inside the shoe by constructing the shoe sole from a softer, more resilient material or incorporating fluid filled pads or bladders in the shoe. The use of gels to provide a conforming fit or cushion is known in the prior art. However, the prior art gels generally set to fit the contours of a foot and do not provide a soft cushion fit or they are soft liquid gels that must be placed in a bladder.

In other shoes designed to provide cushioning or custom fitting, either an air filled foam or an air "pump" has been used to conform to the foot which is inserted into the shoe. The foam is a material that reacts to foot pressure by allowing the air therein to become compressed and/or escape and therefore resiliently compress upon pressure from the foot. The materials does not have the capability to expand to the non-pressure areas of the foot. Shoes that incorporate an air "pump" fill in air around the foot so that the shoe conforms to the foot therein, but in doing so, increases the pressure on the foot. This increased pressure and foot surrounding air pocket tends to greatly increase the foot temperature. Thus, these solutions provide fit or comfort either by merely displacing at locations of higher pressure or by increasing the pressure completely around the foot. Thus, these shoes do not conform fully to the foot therein at normal pressures.

Summary of the Invention The present invention is directed to a shoe which conforms to contours of a foot inserted into the shoe. The shoe employs a solid foam matrix that contains elements of a soft, highly flowable viscoelastic gel, a foam and/or an environmentally-responsive gel. Preferably, the shoe uses sof elastomeric gel or foamed elastomeric gel to provide a flowable, viscoelastic medium that will conform the foot as the foot is inserted into the shoe. The invention is also directed to the use of a temperature-responsive gel that can react to the heat exerted by the foot inserted into the shoe to provide a conforming medium for fit and cushioning. Each of these gels can be located in proper position by surrounding the gels with a memory foam or other commercially available foams. In a preferred embodiment of the invention, the shoe incorporates an environmentally-responsive gel. An environmentally-responsive gel is a microporous, fast responsive, crosslinked gel obtainable from a polymeric precursor, the gel being of sufficient flexibility to enable the gel to be reversible responsive to a change in an environmental condition. The environmentally-responsive gel can be made from any responsive polymer with side groups that can react with a di- or multi-functional crosslinking molecule. The polymers can have hydroxyl, acid or amine side groups and which have lower critical solution temperatures in aqueous solutions together with water-soluble crosslinkers. Even more particularly, the gel is a temperature-responsive gel and is able to undergo a phase separation which is temperature-induced. Still further, the precursor is preferably a linear polymer or cellulose ether such as hydroxypropyl acrylate/hydroxyethyl acrylate copolymer. Aslo, the water-based fluid used to make the gel can include sucrose in the range of 30% to 60% to vary the reaction temperature.

The invention is also directed to the use of a polyurethane gel that provides a highly flowable viscoelastic medium and does not require a gel bladder. The polyurethane gel can be provided in various hardnesses to provide proper mediums for shoe comfort, including fit and cushioning. The polyurethane gel is preferably a soft elastomer with high sol (plasticizer) fraction which can include a high molecular weight triol (MW greater than 6000) and a diisocyanate. The polyol can be made of Arcol E-452 and the plasticizer can be a Paraffin oil or diproylene glycol dibenzoate. In another embodiment of the present invention, the flowable viscoelastic gel is a butadiene style rubber which can be prepared from oil and polyisobutadiene. Preferably, oil such as Kaydol and a styrene ethylene butadiene styrene triblock medium molecular weight rubber polymer such as Kraton 1650 M. Kaydol is a paraffin (55%) and naphtenic (45%). By increasing the percentage of Kraton, the firmness of the gel can be increased for various locations where a firmer gel is desired. Still further, plastic, expanded, resilient, hollow microspheres such as Expancel 091 DE80, expanded glass hollow microspheres or a blowing agent can be added to the gel to reduce weight or the gel can be frothed with air using ultrasonic cavitation. Still further, the foam can be comprised of a polyurethane foam with hollow microspheres or a blowing agent. In another embodiment, a memory foam can be comprised of a polyol, antifoam agent, catalyst and Ioscyanate.

The invention is directed to a shoe that conforms to the foot contours by incorporating a shoe upper that is comprised of three layers; the shoe outer layer, the shoe inner layer, and conforming layer therebetween. The conforming layer can be comprised or portions made from highly flowable, viscoelastic gels, foam and temperature-responsive gels. Preferably, the invention includes soft, highly flowable viscoelastic gel provided in areas of the shoe that correspond to those areas of the foot that are generally highly contoured or have greater curvature for better fit and comfort. In areas where stability or shock cushioning is desired, a more viscous (less flowing gel) is used and in areas where fit and comfort are required, a softer, less viscous (more flowing) gel is used.

As stated above, the invention can also include a temperature-responsive gel that reacts to the heat dissipated from the foot inserted into the shoe to express a liquid that will fill a bladder to allow the show to further conform and provide cushioning and securing fit for the foot therein. Further, the invention is directed to a shoe incorporating a tongue which can have portions made from highly flowable, viscoelastic gels and temperature- responsive gels to provide a customized fit and cushioning to the top of the foot that has been inserted into the shoe. Still further, the present invention is directed to a shoe which conforms to the foot by providing a foot bed comprised of viscoelastic gels and/or temperature- responsive gels therein to conform to and provide cushioning for the foot bottom. Preferably, the shoe foot bed is formed of a low-flowable, harder gel such that it provides supportive cushioning for the foot bottom, for absorbing the impacts of walking and the like. Further, the foot bed should provide a soft, highly flowable gel to provide custom fit and comfort for the foot and, particularly for the foot arch and heel. This is preferably accomplished with the proper placement of various elastomeric gels having proper hardness and viscosities to provide comfortable and supportive viscoelastic mediums against the foot. Still further, the foot bed is formed with the combination of gels encapsulated in a polyurethane foam or preferably a memory foam matrix. This provides customizable fit, comfort, cushioning and stability all in the same system.

The present invention is also directed to a method of forming a customized fitting shoe. The method includes forming a shoe upper which is comprised of the steps of molding flowable, viscoelastic gel and foam to form a conforming layer of a shoe upper. Preferably, the method of forming a customized fitting shoe upper is comprised of the steps of pouring flowable viscoelastic gel into proper locations of a mold, pouring polyurethane foam or memory foam ingredients into the mold, closing the top of the mod which can have the shoe inner layer attached thereto, heating the mold a removing the gel, formed foam and shoe inner layer. Then a temperature-responsive gel and bladder containing the same can be placed in proper locations and an outer layer can be attached to the opposite side of the conforming layer from the inner layer.

Still further, the method includes forming a temperature-responsive gel and bladder by vacuum forming an approximately 10 mil thick plastic bottom film into a mold, placing a die cut temperature responsive gel which is at a relatively cold temperature into the mold cavity, placing a flat top layer of approximately 5 mil thick plastic film over the mold, attaching the top and bottom films using radio frequency or other method.

Even still further, the present invention is directed to a method of forming a shoe foot bed comprising the steps of pouring relatively hard, high viscosity, viscoelastic gel into the foot bed heel plug section of a mold, pouring a relatively soft, highly flowable, viscoelastic gel into proper locations of the mold for providing a conforming fit and comfort, pouring polyurethane foam or memory foam ingredients into the mold, covering the mold with the mold top, which can have the foot bed cover fabric attached thereto, and heating the mold. In another aspect of this disclosure, the shoe incorporates a reversibly gelling polymer network exhibiting a dramatic change in viscosity in response to a change in an environmental stimulus. The reversibly gelling polymer network may contain a responsive component capable of aggregation in response to a change in environmental stimulus and a structural component which supports and interacts with the responsive component in an aqueous-based solvent. The reversibly gelling polymer may be a triblock polyol of the general formula (EO)(PO)(EO), either alone or prepared according to the invention in the presence of other gel polymers.

As used herein, as responsive component is an oligomer or polymer which will respond to a stimulus to change its degree of association and/or agglomeration. The stimulus may be temperature, pH, ionic concentration, solvent concentration, light, magnetic field, electrical field, pressure or other triggers commonly used to trigger a responsive gel material. The aggregation may be in the form of micelle formation, precipitation, labile crosslinking or other factors.

As used herein, the structural component is an oligomer or polymer which supports and interacts with the responsive component so that a multi-material, responsive polymer network is formed. The structural component is not required to be responsive. The interaction of the structural and responsive components, exhibits a synergistic effect, which magnifies the effect of the responsive component in viscosifying and/or gelling the solution. It may also cause a sol-gel transition to occur under conditions which would show no apparent effect in the absence of the polymer network. In the absence of the structural component, the responsive component may or may not show a change in viscosity in response to a change in environmental stimulus. However, if it does show a response in the absence of the structural component, that response is qualitatively or quantitatively different. That is, the response is amplified or altered in the presence of the structural components.

The responsive and structural components are dissolved in an aqueous-based solvent. Since a gel comprises a three-dimensional polymeric network dissolved in a solvent, the liquid component makes up the responsive polymer network.

The novel interaction between the constituent polymers in the responsive polymer network permits formation of gels at very low solids content. Gelation and/or viscosification is observed in aqueous solutions having about 0.01 to 20 wt% of the responsive component and about 0.01 to 20 wt% of the structural component.

A typical reversibly gelling polymer network may be comprised of less than about 4 wt% of total polymer solids of which less than about 2 wt% is the responsive component and less than about 2 wt% is the structural component. The balance is made of the aqueous based solvent. An exemplary responsive component is a triblock polyol having the formula (EO)(PO)(EO). An exemplary structural component is sodium acrylate which is manufactured by polymerization of acrylic acid in the presence of the triblock polyol followed by hydration and neutralization of the polyacrylic acid. The viscosity of the gel increases at least ten-fold with an increase in temperature of about 5°C.

By "gelation", as that term is used herein, it is meant a drastic increase in the viscosity of the solution. Gelation is dependent on the initial viscosity of the solution, but typically a viscosity increase in the range of 5- to 100-fold, and preferably 10- to 50-fold, is observed in the present systems. The gelled state has sufficient mechanical strength to conform and provide support to the foot.

By "triblock polyols", as that term is used herein, it is meant a polymeric or oligomeric structure having a general formula of (P_)_(P_)_b(Pι)_a> where Pj and P₂ represent two different polyol blocks. By way of example only, P_! may be a polyol of the general formula (CH₂CH₂0)_a, where a is in the range of 10-50 and

P₂ may be a polyol of the general formula, (CHRCHRO)_b, where R may be H or an alkyl group, and where b is in the range of 50-70. Other possible polyol combinations are contemplated within the scope of the invention.

The reversibly gelling polymer network may be incorporated into the shoe as described herein above and below for the environmentally responsive gel. That is, the reversibly gelling polymer gel network may be incorporated into the shoe upper as a conforming layer. The conforming layer may additionally comprise highly flowable viscoelastic gels and/or foam. The reversibly gelling polymer gel network reacts to the heat dissipated from the foot inserted into the shoe to undergo a reversible change in viscosity to form a gel within a bladder housed within the shoe upper which allows the shoe to further conform and provide cushioning and securing fit for the foot therein.

The present disclosure is further directed to a method of forming a customized fitting shoe. The method includes forming a shoe upper by molding flowable, viscoelastic gel and form to form a conforming layer of a show upper, as described hereinabove. Then a reversibly gelling and a bladder containing the same can be placed in the proper locations and an outer layer can be attached to the opposite side of the conforming layer.

A reversibly gelling polymer gel network and bladder may be formed by providing a lower and upper plastic film, filling the mold with the reversibly gelling polymer in a cooler liquid or warmer viscous state into the mold and sealing the assembly.

In another aspect of this disclosure, a system for proving support to the human foot is provided which includes a thermally responsive polymer gel contained in a polymer membrane of limited water solubility and located within an article of footwear. The thermally responsive gel exhibits a dramatic change in viscosity in response to a change in temperature around the use temperature. The thermally gelling polymer is designed to be fluid below the expected use temperature and to increase viscosity or otherwise provide support when the gel is exposed to the use temperature. As used herein, the expected use temperature is the temperature to which the gel.bladder system will normally be raised due to heat evolution by the foot. It is expected that the concept of the expected use temperature will involve a transition range of the gel. In other words, for a system normally expected when the foot is not present to be at room temperature, "below the expected used temperature" might mean temperatures at or below 26.67 °C while "above the expected use temperature" might mean temperatures at or above 32.22 °C. The preceise numerical values of below and above the expected use temperature are applications and system specific. In particular, different parts of the foot can develop different levels of heat and so systems designed for different parts of the foot will have different values of the expected use temperature. It is recognized that individuals have different body temperatures and the gels will have to be tailored to these individuals by adopting the transition range of the gel.

Also as used herein, a gel composite is a structure which contains at least two components: 1) a solidus portion through which a fluid can migrate through convection or other mass transfer methodolofy and 2) a reversibly conformable gel. A specific example of a gel composite would be an open cell foam structure impregnated with a reversibly conformable gel. In this case of this impregnated form, below th eexpected use temperature, the gel can flow freely through the pores of the foam providing a soft malleable structure, while above the expected use temperature, the increase in vicosity prevents the fluid from flowing through the pores of the foam providing a much more rigid supporting structure.

The minimum useful support viscosity is defined as the applications determined minimum viscosity of a thermally reversible polymer gel above the expected use temperature which viscosity will enable the system to provide the necessary fit, comfort, support and/or mechanical protection to the foot. The maximum useful flow viscosity is defined as the applications determined maximum viscosity of a thermally reversibly polymer gel below the expected use temperature which viscosity will enable the gel in the system to flow and redistribute itself readily.

Brief Description of the Drawings

Figure 1 is a perspective view of a shoe according to the present invention and incorporating a temperature-responsive gel and bladder for the same; Figure 2 is a perspective view of a conforming layer of the shoe according to the present invention;

Figure 3 is an enlarged, cross-sectional view of the temperature-responsive gel bladder in the shoe upper; Figure 4 is a cross-sectional view of the heel of a shoe according to the present invention incorporating viscoelastic gel and foam therein to conform to the foot;

Figure 5 is a cross-sectional view of the temperature-responsive gel and bladder in the expanded state; Figure 6 is a cross-sectional view of the temperature-responsive gel and bladder in the contracted state;

Figure 7 is a top view of the conforming layer of a shoe tongue according to the present invention;

Figure 8(a) is a top view of a foot bed according to the present invention; Figure 8(b) is a side view of a foot bed according to the present invention;

Figure 8(c) is a bottom view of a foot bed according to the present invention;

Figure 8(d) is a sectional view taken along the line XX in Figure 8a; Figure 9(a) is a top view of a second embodiment of the foot bed according to the present invention;

Figure 9(b) is a cross-sectional, side view of the second embodiment of the foot bed according to the present invention;

Figure 10 is a flow chart of the method used to construct the shoe upper according to the present invention; Figure 11 is a flow chart of the method used to construct the foot bed according to the present invention;

' Figure 12 is a graph of viscosity versus temperature for a 1 wt%, 2 wt% and 3 wt% reversibly gelling polymer network composition of a triblock polyol/polyacrylic acid (1:1) at pH 7.0 measured at a sheer rate of 0.44 sec^"1; Figure 13 is a plot of endotherms for a (a) 1 wt% Pluronic F127 and (b) 1 wt% reversibly gelling polymer networks composition of Pluronic F127/polyacrylic acid (1:1); Figure 14 is a viscosity versus temperature curve of (a) 17 wt% Pluronic F127 and (b) 17 wt% Pluronic F127 in lwt% hydroxyethyl cellulose measured at a sheer rate of 1 rpm;

Figure 15 is a viscosity versus temperature curve for 17 wt% Pluronic F127 measured at a sheer rate of 1 rpm;

Figure 16 is a viscosity versus temperature curve for 30 wt% Pluronic F68 with increasing amounts of sodium chloride measured at a sheer rate of 0.3 rpm;

Figure 17(a)-(c) are cross-sectional views of bladders for use in the present invention; Figure 18 is a temperature versus wt% curve for Pluronic F127 illustrating gel domain;

Figure 19 is a temperature versus wt% Pluronic F68 curve illustrating gel domain;

Figure 20 is a temperature versus wt% Pluronic P103 curve illustrating gel domain;

Figure 21 is a temperature versus wt% Pluronic P105 curve illustrating gel domain;

Figure 22 is a temperature versus wt% Pluronic F87 curve illustrating gel domain; Figure 23 is a temperature versus wt% Tetronic 904 curve illustrating gel domain;

Figure 24 is a temperature versus wt% Tetronic 908 curve illustrating gel domain;

Figure 25 is a temperature versus wt% Plurafac A38 curve illustrating gel domain;

Figure 26 is a temperature versus wt% Plurafac A38 curve illustrating gel domain;

Figure 27 is a temperature versus wt% Pluronic F108 curve illustrating gel domain; Figure 28 is a temperature versus wt% Pluronic F88 curve illustrating gel domain; Figure 29 is a plot of viscosity versus temperature for a 1 wt% reversibly gelling polymer network composition of Pluronic F88/polyacrylic acid (1:1) at pH 7.0 measured at a sheer rate of 2.64 sec^"1 with a SC4-18 spindle; and

Figure 30 is a plot of viscosity versus temperature for a reversibly gelling polymer network composition of 2.5 wt% Pluronic F127/polyacrylic acid (1:1) prepared in (a) deionized water and (b) 0.5 M NaCI solution.

Description of the Preferred Embodiment

Referring to Figure 1, the preferred embodiment of the present invention is a shoe 10 that incorporates a shoe upper 12 and a shoe sole 14. Inside the shoe 10 and not shown is a shoe mid-sople. The shoe upper 12 is comprised of an outer layer 20 and an inner layer 22. In between the inner and outer layer is a conforming layer 24 as disclosed in Figure 2. In the preferred embodiment, the inner layer 22 is made of brush nylon or leather and the outer layer 20 is made of leather.

The conforming layer 24 in Figure 2 is comprised of a first flowable viscoelastic gel portion 50, a second temperature-responsive gel portion 30 and its bladder 32 and third foam portion 40.

The viscoelastic gel section 50 is preferably comprised of a flowable viscoelastic gel that is incompressible, i.e., it retains its volume upon compression. Therefore, this material, when compressed by pressure from the foot inserted into the shoe, will flow into another location where the pressure is not as great. In the preferred embodiment, the viscoelastic gel is molded into a body section 54 and a plurality of connected fingers 52. This enables the viscoelastic gel 50 to conform the foot inserted into the shoe. And as one skilled in the art would appreciate, the viscoelastic gel section 50 can be molded in many shapes. However, in the preferred embodiment, the viscoelastic gel 50 should be molded into areas of the shoe which correspond to highly contoured areas of the foot. For instance, the heel of the foot generally tends to be very contoured and, therefore, the viscoelastic gel section 50 is preferably located so that the shoe can substantially conform the foot heel. Thus the viscoelastic gel 50 preferably extends to correspond to the heel bone and malleoli bones of the foot. Preferably, the viscoelastic gel is comprised of a polyurethane gel, but other gels which disclose the desired properties of elasticity and flowing nature can also be used. In the shoe upper, the viscoelastic gel is preferably of a relatively soft, highly flowable gel. That is, the gel has a -000 hardness of approximately 10 to 100 and preferably about 40. Moreover, the viscoelastic gel portion can be formed of various hardnesses to best conform to the foot. For example, the body section 54 can be made from a soft gel of approximately 40 to 60 -000 hardness and the extending fingers can be made from the same gel hardness or a gel having a lower hardness and being more flowable. Another advantage to using a viscoelastic gel is that the gel does not need to be encapsulated into a bladder, i.e., the gel is not surrounded by a plastic liner to limit the flow thereof. Since the preferred material is a flowable gel, it can be formed directly between the front and back layers 20 and 22.

In one embodiment, the flowable viscoelastic gel is a soft elastomer with high sol (plasticizer) fraction which can include a high molecular weight triol (MW greater than 6000) and a diisocyanate. The polyol can be made of Acrol E-452 brand polyol and the plasticizer can be a Paraffin oil or dipropylene glycol dibenzoate.

In another embodiment, the flowable viscoelastic gel is a butadiene style rubber. The rubber can be prepared from oil and polyisobutadiene. Preferably, oil such a Kaydol and a styrene ethylene butadiene styrene tri block medium molecular weight rubber polymer such as Kraton is used. More preferably, 60 ml of Kaydol and 7.5 g of Kraton 1650 M are mixed and heated to 140° F for one hour. The material is stirred twice during the one hour and then poured into a cool and set into a gel. By increasing the percentage of Kraton, the firmness of the gel can be increased for various locations where a firmer gel is desired or vice versa. Still further, expanded, resilient, plastic, hollow microspheres such as Expancel 091 DE80, expanded, glass microspheres or a blowing agent can be added to the gel to reduce the weight of the gel. Still further, the gel can be frothed with air using ultrasonic cavitation or unexpanded Expancel DU grade microspheres can be used and expanded during processing. A temperature-responsive gel is described as a crosslinked three dimensional polymeric network that contains a substantial quantity of liquid so that the properties of the gel are determined by both the polymeric network and the liquid. If the liquid is water, the gel is commonly called a "hydrogel." The volume of this type of "reaαive gel" may contract by a factor of up to several hundred percent when the gel undergoes a change in external conditions, such as temperature, Ph, solvent or solvent concentration, ionic concentration, light, pressure or electric field. Preferably, the gel used for this application is of the type that reacts to temperature and/or pressure and recovers once the external condition is removed. The network material of a responsive hydrogel as used in the preferred embodiment, may be comprised of a number of polymeric materials that possess a lower critical solution temperature (LCST). The term LCST is the temperature below which the polymer is substantially soluble in liquid and above which the polymer is substantially insoluble. Therefore, the responsive gel forms a two phase system.

The preferred temperature-responsive gel portion 30 is comprised of a hydrogel gel. Examples of gels are given in U.S. Patent No. 5,183,879 and PCT Patent Application No. PCTUS94/05400 which are incorporated herein by reference. The preferred temperature-responsive gel contracts upon application of heat from the foot inserted within shoe 10 and thereby extracts water from the gel. As the shoe temperature rises from the foot that is inserted therein and moves during normal activity, the gel contracts. Therefore, the temperature-responsive gel section 30 can be located anywhere in the shoe to assist in conforming to the foot contours, but, preferably, is located at the shoe mid-section which generates substantial heat. The gel bladder 32 is used to contain the water solution 34 that is expelled from the contracted gel and allows the water solution 34 to flow around and conform to the foot that is inserted into the shoe. Preferably, the bladder 32 extends from the quarter 35, around the collar 36 to the achilles tendon area 38 for providing support for the collar, which assists in maintaining the foot within the shoe, and for assisting in protecting the achilles tendon.

Referring to Figure 3, an enlarged section of the gel bladder 32 is shown in a cavity 32c formed between the outer layer of shoe material 20 and the inner layer of shoe material 22. In the preferred embodiment, the gel bladder 32 is extended from the temperature-responsive gel portion 30 in the quarter 35, around the collar 36 to the achilles tendon section 38 such that water solution 34 can be distributed from the midsection of the foot towards the heel location and allows the shoe to better conform thereto as the shoe is heated.

In this embodiment, the temperature-responsive gel in the shoe is an environmentally-responsive gel. An environmentally-responsive gel is a microporous, fast responsive, crosslinked gel obtainable from a polymeric precursor, the gel being of sufficient flexibility to enable the gel to be reversibly responsive to a change in an environmental condition such as temperature. The gel can be made from any responsive polymer with side groups that can react with a di- or multi¬ functional crosslinking molecule. The polymers can have hydroxyl, acid or amine side groups and which have lower critical solution temperatures in aqueous solutions together with water-soluble crosslinkers. Even more particularly, the gel is preferably a temperature-responsive gel and is able to undergo a phase separation or phase transition which is temperature induced. Still further, the precursor is preferably a linear polymer or cellulose ether, and more particularly, hydroxypropyl acrylate/hydroxyethyl acrylate copolymer. Preferably the hydroxypropyl acrylate/hydroxyethyl acrylate copolymer gel is comprised of between 50 to 100 percent hydroxypropyl acrylate and between 50 to 0 percent hydroxyethyl acrylate. Also, the water-based fluid used to make the gel can include sucrose in the range of 30% to 60% to vary the reaction temperature. Further, to enable the temperature- responsive gel to operate at lower temperatures, glycerin or glycol can be added to reduce the freezing temperature of the solution. The foam portion 40, which makes up the remainder of the conforming layer 24, can be made of many standard foams that are available. The foam portion 40, however, is preferably made of a memory foam, i.e., a foam that deforms upon compression and once the pressure is released, will slowly return to its original position. The foam portion 40 is preferably made with to a Shore C hardness of approximately 25. The form portion 40 is used to surround and secure the flowable, viscoelastic gel portion 50 and the temperature-responsive gel portion 30. The foam portion 40 can be comprised of a polyol, antifoam agent, catalyst and Isocyanate. Still further, the memory foam can be formed from approximately 58% Arcol LG-168, approximately 1% water, approximately .5% Dabco 131, approximately .5% Dabco 33LV and approximately 40% Isocyanate 2143L. Figure 4 discloses a cross-section of the preferred embodiment of the shoe heel wherein the plurality of viscoelastic fingers 52 are disclosed extending in the vertical direction up the shoe heel so that the viscoelastic material can conform to the foot that is inserted therein. The viscoelastic fingers 52 are molded and then encapsulated by the foam material 40. The fingers extend into the concave contours of the foot heal to provide a more securing fit.

The temperature-responsive gel 30 and gel bladder 32 are shown in the expanded or cool state in Figure 5. As stated above, the temperature-responsive gel 30 is expanded at temperatures below the lower critical solution temperature, which should be between approximately 60 to 90 degrees Fahrenheit. In the expanded state the gel contains a water-based solution therein. Thus, the bladder 32 is relatively empty when the gel 30 is expanded.

The temperature-responsive gel 30 and gel bladder 32 are shown in the contracted or heated state in Figure 6. The temperature-responsive gel 30 is heated due to the heat emitted from the foot inside the shoe. As the temperature- responsive gel 30 is heated above lower critical solution temperature the gel contracts and the water solution 34 therein is expressed from the gel and into the bladder 32. Thus, the water solution 34 dynamically flows to areas under less pressure as the shoe is heated. This enables the shoe to dynamically conform to the foot that is inserted therein. As the temperature-responsive gel 30 cools when the foot is removed from the shoe the gel expands and retracts the water solution 34 from the bladder 32. In other words, the temperature-responsive gel 32 returns to its expanded state as shown in Figure 5.

Figure 7 discloses the preferred embodiment of the shoe tongue conforming layer 60. The shoe tongue 16 is shown in Figure 1 and is attached to the shoe 10 such that it covers a portion of the top of the forefoot that is inserted into the shoe 10. The conforming layer 60 is preferably comprised of a temperature-responsive gel portion 62 including gel bladders 64 extending thereabout, a viscoelastic gel portion 66 and a foam portion 68 enveloping both of the gel sections 62 and 64. The tongue conforming layer 60 is enveloped by an inner layer and an outer layer (not shown) substantially similar to the inner and outer layers of the shoe upper discussed above. The shoe tongue is then attached to the shoe upper along the bottom edge 70.

Figures 8(a)-8(d) discloses a foot bed 80 incorporating a foam main body section or foam pad 82, a plurality of relatively soft, flowably viscoelastic gel sections 84, relatively soft, flowably viscoelastic gel fingers 86 and a relatively hard, viscoelastic gel heel plug insert 88. Again, the viscoelastic gel sections could be located anywhere in the foot bed, but are preferably placed such that the relatively soft, flowable gel corresponds to those sections where the foot has the greatest contours and the relatively hard, higher viscosity gel corresponds to where the foot is subject to the greatest impact from walking, running or other activity. Thus, in the preferred embodiment, the viscoelastic gel section 84 and fingers 86 correspond to the foot arch area and extend around to the areas that correspond to the foot heel. The gels are again made to a -000 hardness between 10 and 100 and preferably in the range of 40 to 60.

The viscoelastic gel heel plug insert 88 is preferably located in the bottom of the foot bed to provided cushioning and shock absorption for the foot heel. This insert is preferably made of a gel having a -000 hardness between 20 and 60 and more preferably of approximately 40 to 50. The viscoelastic heel plug insert 88 preferable includes a plurality of ribs 89 to provide additional cushioning and absorption of shock for the foot heel. The foot bed 80 also includes a foam heel plug 90 which is preferably formed of the same foot bed foam as the main body 82.

The preferred foot bed 80 also includes a plurality of grooves 92 that allow the flowable viscoelastic gel to extend up the back of the heel and that increase the flexibility of the foot bed 80. These grooves 92 are shown as extending around the outer edge of the foot bed and substantially in the vertical direction to provide proper flexibility of the foot bed. Figures 9(a)-(b) disclose a second embodiment of a foot bed according to the present invention. The foot bed 81 includes the highly flowable viscoelastic section 84 a :d fingers 86 and the harder viscoelastic heel plug 88. The foot bed 81 further includes a metatarsal pad 94 with ribs 96 for providing cushioning to the foot. Still further, the foot bed includes wing members 98 with gel sections 100. These gel sections 100 can be made of the temperature-responsive gel and the water solution therein can flow in fingers 102 or the gel sections 100 and the fingers 102 can be made of the highly flowable viscoelastic gel. This provides a customized fit for the fore foot. Moreover, the wing members 98 can be provided with different thicknesses so that the customer can chose one that provides the most comfortable fit. Figure 10 presents a flow chart of a method of forming a conforming shoe. The steps include forming a conforming shoe upper, as shown in Figure 2, or tongue, as shown in Figure 7, by pouring flowable, viscoelastic gel and foam ingredients into a mold to form a those portion of the conforming layer of the shoe upper or tongue. Preferably, the viscoelastic gel is poured into the proper locations of a mold and then the memory foam ingredients are poured into the mold to fill the same. The inner layer of the shoe can be placed in the bottom of the mold before the gel and foam are poured therein such that the gel is formed on the inner layer. However, the preferred method is to attach the shoe inner layer to the top plate of the mold. The mold is closed with the top plate and the mold is heated. Heating can be accomplished by heating either the mold or the mold top or both to solidify the gel and foam. Thus, the flowable, viscoelastic gel and foam are molded onto the shoe inner layer.

The temperature-responsive gel is formed separately from the viscoelastic gel and foam. The temperature-responsive gel cassette and bladder are formed in a separate mold. A first layer of plastic film is placed into the mold. Preferably, the plastic film is about 10 mils thick and is a polyurethane film or a laminated film such as surlyn/polyethylene laminated film, to increase the water retention in the gel bladder. This film is vacuum formed over a cavity that is approximately 40 to 80 thousands of an inch thick. The responsive gel material is added at a relatively low temperature, preferably around 0 degrees Celsius to keep the gel saturated with the water-based solution. Then a flat top layer of plastic film is laid over the mold. The top layer is preferably about 5 mils thick and formed of a polyurethane film or a laminated film such as surlyn/polyethylene laminate. The top and bottom layer films are then bonded by radio frequency bonding or other method.

The conforming layer of the shoe upper or tongue is completed by placing the temperature-responsive gel and bladder containing the same in the proper locations and attaching the shoe outer layer to the inner layer such that the conforming layer is between the outer layer and the inner layer.

After the shoe upper or tongue is formed, it is attached to the shoe in an ordinary manner. The invention also includes another method that can be used to form adjacent regions of foam (polyurethane or other foam) and viscoelastic gel material. In this method, the foam and gel can be chemically bonded or unbonded and merely adjacent. More particularly, the method includes the steps of pouring foam material into a mold. Then viscoelastic gel with unexpanded microspheres can be injected into the mold cavity by a separate operation. The mold is then heated to a temperature above the expansion temperature of the microspheres. Depending on the temperature the mold is heated to, the expansion of the microspheres can be controlled to vary the pressure in the molded part.

Referring to Figure 11, a shoe foot bed, as shown in Figures 8(a)-8(d) or 9, is formed by pouring relatively hard, high viscosity, viscoelastic gel into the foot bed heel plug section of a mold, pouring a relatively soft, low viscosity, viscoelastic gel into desired locations that can include the arch area and sections around the foot heel and pouring a foam ingredients into the mold and covering the mold with the mold top with the foot bed cover fabric attached thereto and heating the mold. The reversibly gelling polymer network exhibits flow properties of a liquid at about room temperature, yet rapidly thicken into a gel consistency of at least about five times greater, preferably at least about 10 times greater, and even more preferably at least about 30 times and up to 100 times greater, viscosity upon exposure to the particular environmental trigger. The thermally reversible gelling polymer may comprise a single polymer which responds to changes in temperature. In particular, the reversibly gelling polymer may be a triblock polyol. Alternatively, the responsive polymer network of the present invention may comprise a polymer-polymer composition in which the two or more polymer phases are mutually interacting without covalent bonding between the two polymers. The interacting nature of the two (or more) polymer phases provide a stable miscible composition, irrespective of the immiscibility of the constituent polymers, and unique properties. Such stability and properties may be attributed to specific interactions of the constituent polymers.

The responsive component undergoes a change in conformation in solution. One type of responsive component is a temperature-sensitive aggregating polymer. A temperature-sensitive aggregating polymer undergoes conformational changes and changes to the critical micelle concentration as a function of temperature. The polymer will change from an open, non-aggregated form to a micellular, aggregated form with changes in temperature.

The structural component may be a polymer which is capable of ionization with a change in ionic strength of the solution. Changes in ionic strength may be accomplished by a change in pH or by a change in salt concentration. Changes to the ionic state of the polymer causes the polymer to experience attractive (collapsing) or repulsive (expanding) forces. Because of the hydrogen-bonding capability of these ionizing polymers and of the responsive component, it is hypothesized that the formation of the polymer network of the invention involves molecular interaction and, in particular, hydrogen bonding interaction between the constituent polymers. Ionization is not required, however, and the structural component may be neutral or uncharged.

The responsive polymer network of the present invention may be prepared as an aqueous gel composition, which exhibits a reversible gelation upon exposure to a change in an environmental stimulus. Suitable environmental stimuli which may be used to initiate gelation include pH, temperature, ionic strength and solvent composition. The responsive polymer network may exhibit a reversible gelation in response to one or more environmental changes. The gelation may occur in response to an indirect environmental trigger, for example, light irradiation or electric field application which generates an increase in temperature. Responsive polymer network gel compositions which exhibit a reversible gelation at body temperature (32-37 °C) and/or at physiological pH (ca. pH 7.0-7.5) are particularly preferred for certain medical and pharmaceutical uses. Responsive polymer network compositions which exhibit a reversible gelation at 70 °C or above are particularly preferred for oil field applications. Yet it is within the scope of the present invention for reversible gelation to occur at much higher or lower temperatures or pHs or in response to other stimuli.

The responsive component of the present invention may be any polymer which forms aggregates as a function of temperature. The responsive component typically possess regions of hydrophobic and hydrophilic character. The responsive component may be linear or branched. As will be apparent to one skilled in the art, a nonionic surfactant, due to its hydrophobic and hydrophilic character, may be suitable for use in the invention.

Suitable responsive components include polyoxyalkylene polymers, such as block copolymers of different oxyalkylene units. At least one polyoxyalkylene unit should have hydrophobic characteristics and at least one polyoxyalkylene unit should have hydrophilic characteristics. A block copolymer of polyoxyethylene and polyoxypropylene may be used in a preferred embodiment of the invention. Another suitable responsive component includes Pluronic^® triblock polyol polymers (BASF) having the general formula (POE)_c(POP)_d(POE)_c, where POP is polyoxypropylene and represents the hydrophobic portion of the polymer and POE is polyoxyethylene and represents the hydrophilic portion of the polymer. Pluronic^® (BASF) triblock polymers are commercially available for in the range of 16 to 48 and b ranging from 54-62. Other exemplary polyoxyalkylene polymers include alkyl polyols, which are a product of alcohol condensation reactions with a terminal alkyl or arylalkyl group. The alkyl group should have hydrophobic character, such as butyl, hexyl and the like. An alkyl polyol may have the general formula R^OCH_jCH^OH, where R is a nonpolar pendant group such as alkyl and arylalkyl and the like, and n is in the range of 5-1000. A preferred alkylpolyol is polyethyleneglycol mono(nonylphenyl)ether. Still other exemplary responsive components may include cellulosic, cellulose ethers and guar gums which possess hydrophobic and hydrophilic regions along the polymer backbone which permit aggregation behavior. One or more responsive components may be used in the responsive polymer network composition of the present invention.

Another type of structural components is an ionizable polymer. These materials typically are responsive to changes in pH and/or ionic strength. The ionizable polymers of the present invention include linear, branched and/or crosslinked polymers. Of particular interest are carboxyvinyl polymers of monomers such as acrylic acid, methacrylic acid, ethacrylic acid, phenyl acrylic acid, pentenoic acid and the like. Polyacrylic acid is a preferred carboxyvinyl polymer. One or more poly(carboxyvinyl) polymers may be used in the responsive polymer network compositions of the present invention. Acrylamides or substituted acrylamides are also preferred embodiments. Copolymers, such as by way of example only, copolymers of acrylic acid and methacrylic acid, are also contemplated. Naturally occurring polymers such as chitosan or hyaluronic acids are also possible as structural polymers since they are capable of forming an ionized network as polymers or copolymers of other structural polymers.

As is clear from the description of the invention and from the Examples set forth below, covalent cross-linking of either or both of the constituent polymers of the responsive polymer network is not required in order to observe gelation at low solids contents, such as less than 20 wt% or preferably less than about 10 wt%, or more preferably less than about 5 wt% or most preferably less than about 2.5 wt%.

The reversibly gelling responsive polymer networks compositions of the present invention are highly stable and do not exhibit any phase separation upon standing or upon repeated cycling between a liquid and a gel state. Samples have stood at room temperature for more than three months without any noticeable decomposition, clouding, phase separation or degradation of gelation properties. This is in direct contrast to polymer blends and aqueous mixed polymer solutions, where phase stability and phase separation is a problem, particularly where the constituent polymers are immiscible in one another.

The functioning of a component as responsive or structural may be dependent upon the specific environmental trigger being considered. For example, in the polyacrylate/EO/PO/EO system, when temperature is the trigger, EO/PO/EO is the responsive component, however at pH of 2-5, the polyacrylate component is the responsive component.

Exemplary of the dramatic increase in viscosity and of the gelation of the responsive polymer network aqueous compositions of the invention with a change in temperature are the aqueous responsive polymer network compositions shown in Figure 12. Figure 12 is a graph of viscosity vs. temperature for 1%, 2% and 3% aqueous responsive polymer network compositions comprising a triblock polyol of the general formula (POP) (POE) (POP) and polyacrylic acid (1:1) hydrated and neutralized. The viscosity measurements were taken on a Brookfield viscometer at a shear rate of 0.44 sec^'1 at pH 7.0. All solutions had an initial viscosity of about 1080 cP and exhibited a dramatic increase in viscosity to gel point at about 35 °C. Final viscosities were approximately 33,000 cP, 100,000 cP and 155,000 cP for the 1 wt%, 2 wt% and 3 wt% compositions, respectively. This represents viscosity increases of about 30-, 90- and 140-fold, respectively. The properties of the responsive polymer network gel composition may be modified by varying the components and/or the microstructure of the polymer network. For example, use of different polymerization initiators in the formation of the constituent structural component of the responsive polymer network gel was found to decrease the temperature for onset of viscosity by 5°C. Also, different responsive components have been found to exhibit different reversible gelation temperatures. In addition, preparation of a responsive polymer network in a 0.5 M NaCI solution (as compared to distilled water) will result in a 10 °C decrease in the temperature of gelation. Thus, the ionic strength of the aqueous solution may be used to modify the properties of the composition. Although not intended to be bound to a particular mode of operation, it is believed that several factors contribute to this unique and previously unreported stability of responsive polymer networks. The polyoxyalkylene chains such as those of triblock polyol polymers are known to be substantially unfolded and free- flowing at temperatures below a critical temperature of gelling. Above this temperature, the polyoxyalkylene chains have been demonstrated to form agglomerations due to the temperature-dependent association of the hydrophobic component of the polymer. See, Atwood et al. Intl. J. Pharm. 26:25-333 (1985), herein incorporated by reference. The polymer chains fold in on themselves due to hydrophobic interactions between hydrophobic chain blocks. The polymer morphology of the structural polymer may be branched, creating the entanglement with the responsive component which provides the stability of the polymer network. Adachi et ai, which is incorporated herein by reference, report that the polymerization of acrylic acid in the presence of polyoxyethylene resulted in an interpolymer network having a ladder-like structure in which each oxyethylene residue forms a hydrogen bond with an acrylic acid residue. Template-formed polyacrylic acids of this type may contribute to the bonding observed in these new responsive polymer networks.

Figure 13 shows endotherms of (a) 1% Pluronic^® F127 and (b) 1% responsive polymer network (Pluronic^® F127/polyacrylic acid 1:1) obtained using a MCS Differential Scanning Calorimetry System (Microcal, Inc.) by heating samples with the rate of 15 centigrade/hour. Pluronic^® F127 is a triblock polymer made up of ethylene oxide (EO) and propylene oxide (PO) blocks and having the general formula (EO)(PO)(EO), where 70 wt% of the polymer is EO. Broad or sharp endothermic peaks are seen at characteristic temperature of 29° C which coincides with the onset of gelation in the responsive polymer network composition (see, Fig. 1). The peaks are measured to have enthalpy value of 1.26 cal/g. This enthalpy falls within the range reported for Pluronic solutions (see, for instance, Wanka et al, Colloid&Polymer Science, 1990, 268, 101, herein incorporated by reference).

The aforementioned thermal behavior of responsive polymer networks suggests that the observed increase of viscosity at around 30° C is due to aggregation of triblock polyol molecules at this temperature which, because of physical entanglement and/or hydrogen bonding and/or template formation with polyacrylic acid or polyacrylate molecules, serve as temporary cross-links in viscous gel-like structures of interactive polymer networks. Thus, nonionic surfactants should be well suited to the responsive polymer network compositions of the present invention because of their aggregate- and micelle-forming capabilities in water. A general method of making the responsive polymer network compositions of the present invention comprises solubilization of the responsive component in a monomer capable of forming a structural component or formation of a melt of the component materials. Structural components suitable for use in the method are those which exhibit expansion and contraction in response to a change in ionic strength. The monomer is polymerized to the structural component. Polymerization may be accomplished by addition of a polymerization initiator or by irradiation techniques. The initiator may be a free radical initiator, such as chemical free radical initiators and uv or gamma radiation initiators. Conventional free radical initiators may be used according to the invention, including, but in no way limited to ammonium persulfate, benzoin ethyl ether, l,2'-azobis(2,4- dimethylpentanitrile) (Vazo 52) and azobisisobutyronitrile (AIBN). Initiation may also be accomplished using cationic or ionic initiators. Many variations of this methods will be apparent to one skilled in the art and are contemplated as within the scope of the invention. For example, the responsive component may be dissolved in a monomer/water mixture instead of pure monomer. This may be particularly useful in instances where the temperature-sensitive aggregating monomer does not solubilize well in the monomer or in instances where the monomer of the structural component is a solid. It may be desirable to remove unreacted monomer from the resultant responsive polymer network. This may be accomplished using conventional techniques, such as, by way of example, dialysis.

Reverse phase polymerization may be used to prepare responsive polymer network beads by dispersion of the responsive component/ionizable monomer mixture in a nonpolar solvent such as heptane. The aggregating polymer/monomer solution is dispersed with agitation in a nonpolar solvent, such as heptane or hexane, in order to suspend droplets of the solution. Polymerization of the monomer is initiated by conventional means (i.e., addition of a initiator or irradiation) in order to polymerize the monomer and form responsive polymer network beads. See, U.S.S.N. 08/276,532 filed July 18, 1995 and entitled "Useful Responsive Polymer Gel Beads" for further information on the preparation of polymer gel beads, herein incorporated by reference. Such a method may be particularly desirable to provide a heat sink for the heat generated in the exothermic polymerization reaction. Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymers (trade name Pluronics, Poloxamers) in aqueous solutions show similar reverse thermoviscosification properties at much higher solids content.

As an aqueous Pluronic solution is heated up, the temperature exceeds a certain value, called here the lower transition temperature, the viscosity changes by several orders of magnitude. The consistency of the solution changes from that of a liquid to that of a solid gel (like butter). The particular concentration needed to achieve such a transition depends on the kind of Pluronic polymer. For example, Pluronic F127 will not show the gelation properties at concentrations lower than about 16%, whereas other Pluronics may need an even higher concentration. Figure 14 illustrates the viscosification of 17% aqueous solution of Pluronic F127. It also shows that the viscosity can be increased by adding a thickener, in this case 1% of hydroxy ethylcellulose.

Another potentially desirable property of a Pluronic solution is that when the gel temperature is further increased, it can revert to a liquid state. This is useful, for example, in connection with conformable products, where there is a need to distinguish between the effect of contact with human body temperatures, when the materials should be a gel, and a potentially higher ambient temperature (e.g., in a car trunk on a hot day), when the material should be a liquid. Figure 15 shows this effect for a 17% solution of Pluronic F127, both for increasing and for decreasing temperature.

For may potential uses of the material it is desirable to be able to control the exact transition temperature. This can be achieved by varying the Pluronic type, as well as the concentration of a given Pluronic solution. A straightforward way of controlling the temperature is by modifying a solution of given concentration through incorporation of additives, such as salts and polymers. Figure 16 shows the effect of addition of sodium chloride to a 30% solution of Pluronic F68. The transition temperature can be brought down from 45°C to 10°C by addition of 10% (by weight) of NaCI. Suitable bladder materials may consist of a mono or multilayered sealable structure of sufficient MVTR (Moisture Vapor Transmission Rate) to ensure product performance over the lifetime of the product. Some examples include, but are not limited to, hydrocarbon based films, modified hydrocarbon based films, multi layered or composite films with both hydrocarbon and metallic based layers. Additionally, materials such as foams and the like may be adhered to the film for the purpose of making a more efficient (i.e. stronger) material after the phase transition. Films may be sealable using heat/pressure, sonic welding, RF and pressure adhesive sealing techniques. Additionally, vacuum and heat forming of the package may be required.

The bladder may be manufactured using one of three basic techniques, 1) form, fill and seal, and 2) vacuum form, fill and seal, and 3) pouch prefabrication, fill and seal. Form, fill and seal utilizes the formation of the pouch while at the same time the pouch is filled with the responsive polymer network material.

Vacuum form, fill and seal utilizes a vacuum forming step prior to the filling and sealing operations. The bladder material must be somewhat thicker than the form fill and seal case in the material with thin out and weaken at the corners being formed. The hollow that has been formed can be filled with a liquid, or a combination of liquids and solids in one or sequential steps.

Pouch prefabrication, fill and seal utilizes a premade pouch that is filled with liquids and/or solids in a subsequent filling step and then sealed. Variations of this technique may include filling a premade rigid or soft pouch and then sealing or filling a soft pouch utilizing one way valves that are subsequently cut off and sealed. Those skilled in the art will appreciate that the responsive polymer network and bladder containing apparatus of the present invention may be utilized for a wide variety of conformable and cushioning applications.

An increase in the material strength of the reversibly gelling polymers as they change from a liquid to a gel is significant, but it may not be sufficient for some applications. An appropriate system may be designed to augment the strength. Figure 17(a) illustrates a cross-section of a bladder filled with a reversibly gelling polymer solution. As the material thermoviscosifies the bladder becomes harder. The resistance to flow in this design is not very great. It can be improved by incorporation of a foam into the bladder, as illustrated in Figure 17(b). The foam is impregnated with the reversibly gelling polymer solution and provides a resistance to flow. When the material thermoviscosifies, the resistance becomes much greater, and the foam becomes very hard and rigid. Another structural design improving the strength of the viscosified material is presented in Figure 17(c). The bladder is divided into a number of chambers (two are depicted here) separated by narrow channels, through which the solution must flow in order to redistribute itself when pressed or squeezed. When the solution viscosifies, the resistance to flow offered by these narrow channels is much greater than that in the case of an open bladder, as in Figure 17(a). Therefore the overall stiffness of the systems is enhanced.

Because the materials selected for the bladder have a measurable permeability to transport of water, particularly over the expected 2 year minimum lifetime of shoes, it is essential that the system not be one which is sensitive to the expected level of loss of water, which is estimated at a minimum of 10% of the total water. The design rules for this system then call for a material and material concentration which: 1) Display a gelation at the desired temperature.

2) Continues to display the gelation within the desired temperature range even after loss of nominally 10% fluid (or whatever loss of fluid is designed for the particular system) resulting in the Pluronic (poloxomer) being more concentrated. 3) Is fluid at a temperature as low as possible, but at least -5 degrees C.

4) Display the necessary mechanical integrity for the application.

As an example, using the charts "Aqueous Gel Characteristics of Pluronic and Tetronic Surfactants" shown in Figures 18-28. If one would select Pluronic

F127 as the solid and would desire a transition at 25 degrees, then the initial concentration would be 18% solids. After the material loses 10% of the fluid, the concentration becomes 20% solids. According to the chart, the transition temperature would be 22 degrees. If the sensitivity of the application to temperature is not great, this may be satisfactory. On the other hand, if the sensitivity is high, this material may not be acceptable for the particular use. Another example would be the use of Pluronic F68 as the solid. This material would need to be present at a level of 55% to be suitable. If this material lost 10% of its water, then the solids concentration would be 57% which would then have a transition temperature of 22 degrees. Yet another example would be the use of Pluronic P103 which would need to be in the range of 34% concentration to show a transition of 25 degrees. If this material lost 10% of its water, resulting in a concentration of 36%, the transition temperature would drop to 20 degrees, which is also a very sizeable shift in gelation temperature and so a much less suitable materials choice.

On the other hand, if one would use Pluronic PI 05 as the solid the initial concentration would be in the range of 30%. If this material loses 10% of its water, the concentration of solids would be in the 32% range. This material has a change in transition temperature of 24 degrees C, so the shift is very small.

In order to further enhance the usefulness of the environmentally responsive gels and the thermally reversible polymer gels to its application in footwear, a thermochromatic dye can be incorporated into the solution and/or the bladder or container. The user's perception of a radical change in the material properties is then enhanced by a change in the material's color.

Exemplary conformable product applications of the invention include, but are in no way limited to, footwear, such as golf shoes, ski boots, ice skates, in-line skates, roller skates, running shoes, cross-training shoes, volleyball shoes, basketball shoes, tennis shoes, football cleats, baseball cleats, soccer cleats, lacrosse cleats, rugby shoes, field hockey; mouthpieces, helmets, headgear (i.e., wrestling), specialty gloves (i.e., baseball, boxing, biking, golf, lacrosse, equestrian, hockey, etc.), masks (i.e., hockey, lacrosse, baseball catcher, etc.), and lacrosse head stops.

Based on these principles, the user can select the correct poloxomer to meet the requirements of the application. The reversibly gelling polymer network complexes and aqueous gels of the present invention may be understood with reference to the following examples, which are provided for the purposes of illustration and which are in not way limiting of the invention.

Example 1 This example describes the synthesis of a responsive polymer network and an aqueous responsive polymer network solution prepared using a triblock polymer of ethylene oxide and propylene oxide (Pluronic^® F27) and poly (acrylic acid). This example also characterizes the gelation and the physical properties of the resultant responsive polymer network.

Synthesis. Block copolymer of propylene oxide (PO) and ethylene oxide (EO) having sandwich structure (EO)_A(PO)_B(EO)_A (Pluronic F127 NF, Poloxamer 407 NF, where "F" means Flakes, "12" means 12X300=3600 - MW of the poly(propylene oxide) section of the block copolymer, "7" ethylene oxide in the copolymer is 70 wt%, and nominal molecular weight is 12,600) from BASF (3.0 g) was dissolved in 3.0 g acrylic acid (Aldrich). This represents a substantially 1:1 molar ratio of Pluronic^® F127 and polyacrylic acid. The solution was deaerated by N₂ bubbling for 0.5 h and following addition of 100 μl of freshly prepared saturated solution of ammonium persulfate (Kodak) in deionized water was kept at 70° C for 16 h resulting in a transparent polymer.

Viscosity measurements. A known amount of the resultant polymer was suspended in 100 ml deionized water into which NaOH was added. Following swelling for 3 days while stirring, the pH of the resulting fine suspension was adjusted to 7. Samples of 15 ml each were taken, and pH in each vial was adjusted to desired value by addition of 1 M HCl or NaOH. Samples were then kept overnight and their viscosities were measured at different temperatures using Brookfield viscometer using either an SC4-18 or an SC4-25 spindle. A control experiment was done with a physical blend of Pluronic^® F127 and polyacrylic acid (MW 450,000) available from Aldrich. Pluronic^® F127 and polyacrylic acid were dissolved together in deionized water at 1 wt% total polymer concentration and the resultant solution was adjusted to pH 7, stirred and kept in refrigerator. The responsiveness of the responsive polymer network composition and the physical blend to temperature and pH is illustrated in Figs. 1, 2 and 5. Figs. 1 and 2 clearly demonstrate that the synthetic route outlined above resulted in a responsive polymer network polymeric system that is sensitive to pH and temperature of the environment. Note that the liquid-gel transition is very sharp, occurring over a very small temperature change or ΔpH. Fig. 5 is a viscosity vs. temperature graph comparing the gelling characteristics of the responsive polymer network composition and the physical blend. The blend prepared by physically mixing of the triblock EO/PO/EO polymer and polyacrylic acid did not exhibit viscosifying effect either as a function of temperature or pH.

It was generally observed that 1-5 wt% responsive polymer network compositions made of Pluronic^® F127 and polyacrylic acid viscosify at temperatures of around 30 °C and higher if pH is adjusted to 6 or higher. The gelling effect was observed in responsive polymer network compositions standing 3 months or longer. Repeated heating and cooling of responsive polymer network compositions did not cause deterioration of the responsive polymer network or the gelling effect. Solutions of either Pluronic F127 or polyacrylic acid (1-5 w% in water, adjusted to pH 6 or higher) or physical blends of the two lacked the gelling effects found for responsive polymer network compositions.

Example 2. This example describes the synthesis of a responsive polymer network and an aqueous responsive polymer network composition prepared using Pluronic^® F88 Prill and poly (acrylic acid). This example also characterizes the gelation and the physical properties of the resultant responsive polymer network composition.

Synthesis. Block copolymer of propylene oxide (PO) and ethylene oxide (EO) having sandwich structure (EO)_A(PO)_B(EO)_A (Pluronic F88 Prill, where "F" means Flakes, "8" means 8X300=2400 - MW of the poly (propylene oxide) section of the block copolymer, "8" means 80 wt% ethylene oxide in the copolymer is 80%, and the nominal molecular weight is 11,400, 3.0 g) was dissolved in 3.0 g acrylic acid (Aldrich). The solution was prepared as described above for Example 1.

Viscosity measurements. A responsive polymer network composition was prepared and studied as described in Example 1. responsive polymer network compositions of 1 wt% Pluronic^® F88 and polyacrylic acid (1:1) viscosified at temperatures of around 48° C and higher at pH 7, as is illustrated in the viscosity vs. temperature graph of Figure 29. Repeated heating and cooling of responsive polymer network suspensions was not observed to cause deterioration of the gelation effect. This measurement correlates well with the observed characteristic temperature of 47° C of the endothermic peaks that are seen in the DSC endotherm. The peaks are measured to have enthalpy value of 0.9 cal/g. Example 3. This example demonstrates the ability to shift the temperature at which an the polymer network gel viscosifies by addition of a salt into the aqueous solution.

The interpenetrating polymer network was prepared as described in Example 1. The dry polymer was placed into either deionized water or a 0.5 M NaCI solution, in proportions to provide a 2.5 wt% solution. Viscosity profiles for the two aqueous solutions were determined and are reported in Figure 30. The viscosity of a 2.5 wt% solution in deionized water has a higher initial viscosity than that in a 0.5M NaCI solution at 20 °C. Further, the temperature at which gelation occurs shifts from about 35 °C in water to about 30 °C in the NaCI solution. Thus, a change in the ionic strength of the aqueous gel composition alters its gelling properties.

While it is apparent that the illustrative embodiment of the invention herein disclosed fulfills the objectives stated above, it will be appreciated that numerous modification and other embodiments may be devised by those skilled in the art. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments which come within the spirit and scope of the present invention.

What is claimed is:

Claims

1. A shoe that conforms to foot contours and provides cushioning comprising: a shoe sole; and a shoe upper attached to the shoe sole, comprising an outer layer, an inner layer and a conforming layer therebetween, wherein a first portion of the conforming layer is comprised of viscoelastic gel and a second portion of the conforming layer is comprised of environmentally-responsive gel.

2. The shoe of claim 1, wherein the environmentally-responsive gel is a temperature-responsive gel that will react to the heat emanating from a foot inserted into the shoe to express a liquid.

3. The shoe of claim 2, wherein the temperature-responsive gel is a microporous, fast responsive, crosslinked gel obtainable from a polymeric precursor, the temperature-responsive gel being of sufficient flexibility to be reversibly responsive to a change in temperature.

4. The shoe of claim 3, wherein the temperature-responsive gel has lower critical solution temperatures in an aqueous solution and water-soluble crosslinkers.

5. The shoe of claim 3, wherein the precursor is a linear polymer.

6. The shoe of claim 3, wherein the precursor is a cellulose ether.

7. The shoe of claim 3, wherein the precursor is a hydroxypropyl acrylate/hydroxyethyl acrylate copolymer.

8. The shoe of claim 7, wherein the aqueous solution includes sucrose in the range of 30% to 60.

9. The shoe of claim 1, wherein the viscoelastic gel is a polyurethane gel that provides a viscoelastic medium that flows due to foot pressure and thereby provides a conforming fit and cushion to a foot inside the shoe.

10. The shoe of claim 9, wherein the polyurethane gel is not encapsulated within a bladder.

11. The shoe of claim 10, wherein the polyurethane gel is a soft elastomer with high sol fraction.

12. The shoe of claim 11, wherein the polyurethane gel is comprised of a high molecular weight triol.

13. The shoe of claim 12, wherein the high molecular weight triol has a molecular weight greater than 6000.

14. The shoe of claim 10, wherein the polyurethane gel is comprised of a diisocyanate.

15. The shoe of claim 1, wherein the viscoelastic gel is a butadiene style rubber that conforms to the foot and is not encapsulated within a bladder.

16. The shoe of claim 15, wherein the viscoelastic gel is comprised of an oil and polyisobutadiene.

17. The shoe of claim 15, wherein the viscoelastic gel is comprised of a styrene ethylene butadiene styrene triblock medium molecular weight rubber polymer and oil.

18. The shoe of claim 15, wherein the viscoelastic gel is further comprised of hollow microspheres.

19. The shoe of claim 15, wherein the polyurethane gel is further comprised of a blowing agent.

20. The shoe is claim 1, further including a third portion of the conforming layer which is comprised of a memory foam.

21. The shoe of claim 1, wherein the conforming layer first portion is comprised of a first viscoelastic gel portion configured and dimensioned to correspond to a foot heel.

22. The shoe of claim 21, wherein the conforming layer first portion further includes a plurality of viscoelastic gel finger sections extending from the first viscoelastic gel portion.

23. The shoe of claim 1, wherein the conforming layer first portion is configured and dimensioned to correspond to a top portion of a fore foot.

24. The shoe of claim 2, wherein the second portion is configured such that the temperature-responsive gel is secured within a bladder and is positioned in the shoe quarter such that it corresponds to a fore foot and that the liquid can flow through the bladder to correspond to a collar section of the shoe.

25. The shoe of claim 20, wherein the first portion of the conforming layer and the third portion of the conforming layer have different hardnesses.

26. The shoe of claim 25, wherein the first portion of the conforming layer has a -000 hardness of about 40 to 60 and the third portion of the conforming layer has a Shore C hardness of about 25.

27. A shoe foot bed comprising: a foam pad for at least underlying a portion of a foot; a relatively hard viscoelastic gel heel plug secured to the foam pad for underlying at least a portion of a foot heel; and a relatively soft, flowable viscoelastic portion secured to the foam pad for underlying at least a foot arch.

28. The shoe foot bed of claim 27, wherein the relatively soft, flowable viscoelastic portion extends further includes a second flowable gel portion that corresponds to a foot heel.

29. The shoe foot bed of claim 27, wherein the relatively soft, flowable viscoelastic portion further includes a plurality of finger portions.

30. The shoe foot bed of claim 27, further including a metatarsal pad made of a relatively hard, viscoelastic gel for underlying a foot metatarsal.

31. The shoe foot bed of claim 27, further comprising at least one wing portion, wherein the wing portion is comprised of a temperature-responsive gel section.

32. The shoe foot bed of claim 27, further comprising at least one wing portion, wherein the wing portion is comprised of a relatively soft, flowable viscoelastic gel section.

33. A method of forming a shoe, comprising the steps of: molding viscoelastic gel in a mold with a shoe inner layer to form a first portion of a conforming layer that is attached to the shoe inner layer; placing a temperature-responsive gel and bladder containing the same into the conforming layer to form a second portion of the conforming layer; and attaching the shoe outer layer to the inner layer such that the conforming layer is between the inner layer and the outer layer.

34. A method of forming a shoe component comprising the steps of: pouring viscoelastic gel and foam into a mold; laying a fabric layer on top of the mold by attaching the fabric layer to a top plate of the mold; closing the mold with the top plate; heating the mold to form an integral conforming layer and fabric layer.

35. The method of forming the shoe component of claim 34, further comprising the step of attaching an outer layer to the integral conforming layer and fabric layer.

36. The method of forming the shoe component of claim 34, wherein the viscoelastic gel is poured into the mold and then the foam comprising polyurethane gel with microspheres is poured into the mold.

37. the method of forming the shoe component of claim 34, wherein heating the mold includes heating the mold top plate.

38. The method of forming the shoe component of claim 34, further comprising the steps of forming a temperature-responsive gel and bladder and adding the temperature-responsive gel and bladder to the integral conforming layer and fabric layer.

39. The method of forming the shoe component of claim 38, wherein the step of forming the temperature-responsive gel and bladder is comprised of the steps of: placing a first layer of plastic film into a second mold; vacuum forming the first layer of plastic film over the second mold; placing the temperature-responsive gel material into the second mold on top of the first layer; placing a second layer of plastic film over the mold; and bonding the first and second layers together.

40. A shoe that conforms to foot contours and provides cushioning comprising: a shoe sole; and a shoe upper attached to the shoe sole, comprising an outer layer, an inner layer and a conforming layer therebetween, wherein a first portion of the conforming layer is comprised of viscoelastic gel and a second portion of the conforming layer is comprised of thermally reversibly gelling polymer.

41. The shoe of claim 40, wherein the thermally reversibly gelling polymer comprises: responsive component capable of aggregation in response to a change in environmental stimulus and a structural component which supports and interacts with the responsive component.

42. The shoe of claim 40, wherein the thermally reversibly gelling polymer comprises a triblock polyol.

43. A system for providing thermally reversibly conformable mechanical support to the human foot comprising: a thermally responsive polymer gel contained in a polymer membrane of limited water permeability and located within or in an article of footwear as a footbed, sockliner, or an integral bladder, said thermally responsive gel designed to be fluid below the expected use temperature (the temperature to which the gel/bladder system will normally be raised due to heat evolution by the foot) as measured at the point at which the gel is disposed and to increase viscosity or otherwise provide support when exposed to the expected use temperature as measured at the point at which the gel is disposed.

44. The system of claim 43 comprising: a reversibly thermochromic material or other responsive chromic material.

45. The system of claim 43 wherein the viscosity of the gel below the expected use temperature is at or below the maximum useful flow viscosity and the viscosity of the gel above the expected use temperature is at or above the minimum useful support viscosity.

46. The system of claim 43 comprising a gel composite.

47. The system of claim 43 wherein the gel is part of a system designed to give orthotic or prosthetic support.

48. The system of claim 43 wherein the gel is part of a system designed to control motion of the foot, as in an ankle locking system for a ski boot or similar article.

49. The system of claim 43 wherein the gel expands or contracts to release or provide liquid at the expected use temperature.

50. The system of claim 43 wherein the gel contains solutes designed to change the thermal or viscosity properties of the gel.

51. The system of claim 43 wherein the gel contains an antifreeze designed to prevent freezing or boiling at naturally occurring conditions from -25 ° F to + 155° F.

52. The system of claim 43 comprising: a membrane designed to allow permeation of no more than one percent of the fluid over a two year period.

53. The system of claim 43 comprising: a membrane designed to allow permeation of no more than one percent of the fluid over a six month period.

54. The system of claim 43 comprising: a membrane designed to allow permeation of no more than one percent of the fluid over a one month period.

55. The system of claim 43 comprising: a gel designed so that permeation of up to ten percent of the fluid will not change the thermal viscosification temperature or properties.

56. The system of claim 43 comprising: a factor of 3 increase in viscosity measured at .44 sec-1 from below the expected use temperature to above the expected use temperature.

57. The system of claim 43 comprising: a factor 10 increase in viscosity measured at .44 sec-1 from below the expected use temperature to above the expected use temperature.

58. The system of claim 43 comprising: a factor of 30 increase in viscosity measured at .44 sec-1 from below the expected use temperature to above the expected use temperature.

59. The system of claim 43 comprising: a factor of 100 increase in viscosity measured at .44 sec-1 from below the expected use temperature to above the expected use temperature.

60. The system of claim 43 comprising: a factor of 300 increase in viscosity measured at .44 sec-1 from below the expected use temperature to above the expected use temperature.

61. The system of claim 43 comprising: a gel which has a maximum useful flow viscosity such that it can easily be injected or otherwise introduced into a bladder during the manufacturing process.