CROSSLINKED GEL FORMULATION

Abstract

A gel medium containing at least one non-aqueous solvent and a crosslinked polymer resulting from the reaction of a polyfunctional polymer containing at least two carboxyl moieties capable of undergoing crosslinking reactions, the polyfunctional polymer having a molecular weight from 2,000 g/mol to 3,000,000 g/mol, and a crosslinking agent chosen from a polycarbodiimide or a polyaziridine.

Claims

1. A gel medium comprising: a non-aqueous solvent, said solvent being present in the gel medium in at least 30% by weight relative to the total weight of the gel; and a crosslinked polymer resulting from the reaction of: a polyfunctional polymer containing at least two carboxyl moieties capable of undergoing crosslinking reactions, said polyfunctional polymer having a molecular weight from 2,000 g/mol to 3,000,000 g/mol and a crosslinking agent chosen from a polycarbodiimide or a non-toxic polyaziridine.

2: The gel medium according to claim 1, wherein the polyfunctional polymer containing at least two carboxyl moieties is selected from a carboxylic acids functional polyester, a carboxylic acids functional polyether, a carboxylic acids functional polyurethane, a carboxylic acids functional polyacrylate, a carboxylic acids functional polymethacrylate, a carboxylic acids functional polyvinylacetate copolymer, copolymers made from ionic liquids, combinations thereof, reaction products thereof, and copolymers thereof.

3: The gel medium according to claim 1 wherein the polyfunctional polymer is: a) a copolymer prepared from (meth)acrylic acid monomer or C.sub.1-C.sub.4 substituted (meth)acrylic acid monomer and at least one ethylenically unsaturated organic carboxylic monomer containing 3 to 9 carbon atoms and at least one carboxylic group; or at least one C.sub.1-C.sub.12 alkyl(meth)acrylate; or at least one ethylenically unsaturated C.sub.1-C.sub.12 alkene; or at least one aromatic mono-alkenyl monomer; (b) a copolymer prepared from vinyl acetate monomer and at least one ethylenically unsaturated organic carboxylic monomer containing 3 to 9 carbon atoms and at least one carboxylic group; (c) a copolymer prepared from C.sub.1-C.sub.12 alkyl vinyl ether monomer and at least one ethylenically unsaturated organic carboxylic monomer containing 3 to 9 carbon atoms and at least one carboxylic group; (d) a carboxydifunctional PEG or PPG derivative; (e) a multiarm PEG or PPG carboxylic acid terminated derivative; (f) a poly(lactide-co-glycolide) (PLGA) carboxylic acid terminated derivative; (g) a multiarm PLGA carboxylic acid terminated derivative; (h) a poly(ε-caprolactone)-PEG carboxylic acid terminated derivative; (i) a PLGA-PEG carboxylic acid terminated derivative; (j) a PLA-PEG carboxylic acid terminated derivative; (k) a PCL-PEG carboxylic acid terminated derivative; (l) a polyester dendrimer with 2,2-bis(hydroxymethyl)propanoic acid (bis-MPA), trimethylol propane or pentaerythritol as a core; (m) a polyurethane matrix which contains at least two carboxylic moieties, said polyurethane matrix being obtained from the reaction of polyols with alkylene oxides isocyanate compounds; or a mixture or a reaction product thereof.

4: The gel medium according to claim 1, wherein the polycarbodiimide is chosen from an oligomeric material which comprises carbodiimide functions and hydrophilic segment groups having no reactivity towards the carbodiimide functions.

5: The gel medium according to claim 4, wherein the oligomeric material which comprises carbodiimide functions is further substituted by at least an alkylalkoxysilane group or an alkoxysilane group.

6: The gel medium according to claim 1, further comprising a dye, the dye being independently selected from photochromic dyes, electrochromic dyes, dichroic dyes and fixed tint dye.

7: The gel medium according to claim 6, wherein said gel is an electrochromic gel medium and further comprises a redox chemical mixture in solution in said solvent and interspersed in said crosslinked polymer, said mixture being constituted of an electrochromic reducing compound and an electrochromic oxidizing compound, and which is in an activated condition in the presence of an applied voltage and which bleaches to an inactive condition in the absence of an applied voltage.

8: The electrochromic gel medium according to claim 7, wherein the electrochromic reducing compound is selected from ferrocene and their derivatives, phenoxazine and their derivatives, phenazine and their derivatives, phenothiazine and their derivatives, thioanthrene, thiophene, and tetrathiafulvalene.

9: The electrochromic gel medium according to claim 7, wherein the electrochromic oxidizing compound is selected from mono viologens or bis viologens.

10: The electrochromic gel medium according to claim 7, wherein the redox chemical mixture is constituted of one reducing compound and at least one electrochromic oxidizing compound, said at least one electrochromic oxidizing compound being either a compound of formula (Ia) or a compound of formula (IIa): ##STR00154## wherein R.sup.1 and R.sup.2 are each independently selected from: ##STR00155## and X.sup.− is a counterion selected from halide, tetrafluoroborate, tetraphenylborate, hexafluorophosphate, nitrate, methanesulfonate, trifluoromethane sulfonate, toluene sulfonate, hexachloroantimonate, bis(trifluoromethanesulfonyl)imide, perchlorate, acetate and sulfate, ##STR00156## wherein Z is —CH.sub.2—, —(CH.sub.2).sub.2—, —(CH.sub.2).sub.3—, —(CH.sub.2).sub.4—, —(CH.sub.2).sub.5—, —CH.sub.2—CH(CH.sub.3)—CH.sub.2—, —CH.sub.2—CH(CH.sub.2Phenyl)-CH.sub.2—, —(CH.sub.2).sub.2—CH(CH.sub.3)—CH.sub.2—, —(CH.sub.2).sub.3—CH(CH.sub.3)—CH.sub.2—, —(CH.sub.2).sub.2— and CH(CH.sub.3)—(CH.sub.2).sub.2—, and R.sup.3 and R.sup.4 are each independently selected from alkyl and optionally substituted phenyl groups.

11: A device comprising the gel medium according to claim 1, wherein said gel medium is formed by a process comprising: (a) forming a liquid composition comprising the non-aqueous solvent and the crosslinked polymer by mixing outside of said device: the non-aqueous solvent, optionally a dye, the polyfunctional polymer containing at least two carboxyl moieties capable of undergoing crosslinking reactions, having a molecular weight from 2,000 g/mol to 3,000,000 g/mol, and an acid value from 1 to 50 mg KOH/g, and the crosslinking agent chosen from a polycarbodiimide or a non-toxic polyaziridine; and (b) inserting the liquid composition obtained from the forming (a) into said device and allowing to polymerize said polyfunctional polymer and said polycarbodiimide or said polyaziridine thereby forming a crosslinked polymer and forming a gel medium in which compounds of the crosslinked polymer and the non-aqueous solvent are held in a matrix comprising the crosslinked polymer.

12: The device according to claim 11, wherein the content of the polycarbodiimide or polyaziridine is from 0.2 to 30 wt %, relative to the total weight of polyfunctional polymer in the liquid composition.

13: The device according to claim 11, wherein the content of the polyfunctional polymer is from 2 to 60 wt %, relative to the total weight of the liquid composition.

14: The device according to claim 11, wherein said device is a battery, an electrochromic device or a photochromic device.

15: A method of preparing a gel medium, comprising: (a) forming a liquid composition comprising the non-aqueous solvent and the crosslinked polymer by mixing outside of said device: the non-aqueous solvent, optionally a dye, the polyfunctional polymer containing at least two carboxyl moieties capable of undergoing crosslinking reactions, having a molecular weight from 2,000 g/mol to 3,000,000 g/mol, and the crosslinking agent chosen from a polycarbodiimide or a non-toxic polyaziridine; and (b) inserting the liquid composition obtained from the forming (a) into said device and allowing to polymerize said polyfunctional polymer and said polycarbodiimide or said polyaziridine thereby forming a crosslinked polymer and forming a gel medium in which compounds of the crosslinked polymer and the non-aqueous solvent are held in a matrix comprising the crosslinked polymer.

16: The gel medium according to claim 1, wherein the non-aqueous solvent is present in the gel medium in at least 50% by weight relative to the total weight of the gel.

17: The gel medium according to claim 1, wherein the polyfunctional polymer is: (e) a PEG Dendrimer carboxylic acid terminated of formula: ##STR00157## wherein n is an integer from 200-20000.

18: The gel medium according to claim 1, wherein the polyfunctional polymer is: (1) a polyester dendrimer of formula: ##STR00158##

19: The electrochromic gel medium according claim 7, wherein the redox chemical mixture is constituted of one reducing compound and at least one electrochromic oxidizing compound, said at least one electrochromic oxidizing compound being a compound of formula (IIa): ##STR00159## wherein Z is —CH.sub.2—, —(CH.sub.2).sub.2—, —(CH.sub.2).sub.3—, —(CH.sub.2).sub.4—, —(CH.sub.2).sub.5—, —CH.sub.2—CH(CH.sub.3)—CH.sub.2—, —CH.sub.2—CH(CH.sub.2Phenyl)-CH.sub.2—, —(CH.sub.2).sub.2—CH(CH.sub.3)—CH.sub.2—, —(CH.sub.2).sub.3—CH(CH.sub.3)—CH.sub.2—, —(CH.sub.2).sub.2— and CH(CH.sub.3)—(CH.sub.2).sub.2—, and R.sup.3 and R.sup.4 are selected from phenyl groups having formula. ##STR00160##

Description

EXAMPLE

[0237] This invention will be further illustrated by the following non-limiting example which are given for illustrative purposes only and should not restrict the scope of the appended claims.

[0238] The formulation is prepared as followed:

[0239] An electrochromic mixture (3.1%), a copolymer of vinyl acetate and crotonic acid sold as Vinnapas® C501 from Wacker (19.4%) and propylene carbonate (77.5%) are blended together at room temperature until complete dissolution of all the components in the solvent.

[0240] The propylene carbonate, the electrochromic mixture formed of ethyl violologen diperchlorate and 10-methylphenothiazine are all sold by Sigma Aldrich.

[0241] The resulting viscous liquid is mixed with 2% of carbodiimide crosslinker the total weight of polyfunctional polymer in the liquid composition. The carbodiimide crosslinker is a highly viscous liquid. The obtained composition is used immediately to make an electrochromic device. After 1 hour at ambient temperature or a few minutes at 50° C. the liquid has at least partially gelled, enough for it to be able to be move the so-obtained device without inducing optical defects. Thus, said device may be moved from the assembly machine to undergo a post curing step, in an oven for instance. The device is for example post cured at 50° C. overnight.

[0242] The polycarbodiimide crosslinker used is sold under the commercial name Picassian® XL725 by Stahl.

[0243] The curve illustrated in FIG. 1 shows the variation of the viscosity of the mixture as a function of time at room temperature.

[0244] After 24 h the electrochromic device is bended and activated during 100 h. No defects are visible. More precisely, the mechanical deformation does not affect the homogeneity of the coloration.