Polydiacetylene gels

Claim 1

A composition consisting essentially of (A) at least one polydiacetylene selected from the group consisting of 1,4 addition polymers of conjugated diacetylene monomers having the formula R--C.tbd.C--C.tbd.C--R 1 wherein R and R 1 are urethane groups independently selected from (I):--(CH 2 ) n --O--CONH--CH 2 --COOA, where n is an integer of 1-10 and A is C 1 -C 10 linear or branched alkyl; and polymers of diacetylene monomers having said formula R--C.tbd.C--C.tbd.C--R 1 wherein R and R 1 are identical urethane groups selected from: (II):--(CH 2 ) n --O--CONHB wherein (a) n is 2 and B is ethyl, n-butyl or m-chlorophenyl; or (b) n is 3 and B is methyl, ethyl, phenyl or m-tolyl; or (c) n is 4 and B is methyl, ethyl, 2-chloroethyl, o-chlorophenyl, p-chlorophenyl, n-butyl or m-methoxyphenyl; said composition also consisting essentially of (B) a liquid capable of forming a gel with said polydiacetylene and of forming a solution of said polydiacetylene upon elevation of the temperature of the gel to at least the dissolution temperature, said gel containing about 0.001 to 50 weight percent of said polydiacetylene, and said solution having a different color from that of said gel and being capable of reversibly reforming the gel in its original color upon cooling to the gelation temperature; said liquid being at least one member of the group consisting of linear or branched C 5 -C 10 paraffinic hydrocarbons, linear or branched C 1 -C 5 halogenated alkanes containing 1-4 halogen atoms, C 2 -C 4 linear or cyclic alkyl sulfoxides, C 4 -C 6 cyclic sulfones, C 2 -C 7 N,N-dialkylalkanoamides, C 6 -C 10 aromatic hydrocarbons, C 6 -C 10 halogenated aromatic hydrocarbons containing 1 to 4 halogen atoms, C 4 -C 6 linear or cyclic mono-or diethers, C 2 -C 4 alkanoic acid and ethyl esters therof, C 3 -C 6 linear alkyl ketones and C 2 -C 4 halogenated alkanoic acids containing 1 to 3 halogen atoms.