Patent ID: 7812069

Claim:
A reversible viscosity reducing polymer comprising a crosslinkage between polymer subunits, said crosslinkage having the form: where L is covalently bonded to a first polymer subunit and is independently in each occurrence NHR 2 —, [imidazole-R 2 ], HS—, HO—, R 3 OOC—, C(R 2 ) 2 ═CR 2 —, H(R 2 )C═CH—HC═CR 3 , OCN—, XOC—(X═Cl, Br, I), R 2 ≡C—, N 3 —; R 2 is independently in each occurrence hydrogen or C 1 -C 4 alkyl; R 3 is an electron, hydrogen, C 1 -C 4 alkyl; M is a conventional crosslinking agent moiety known to be reactive with L of isocyanate, —OH NH 2 , —COOH; R 4 is in each occurrence independently a nullity or an intermediate linker of C 1 -C 30 alkyl, C 2 -C 30 alkenyl, and C 6 -C 24 aryl; Y D is a Diels-Alder reactive moiety of a diene or dienophile; Y A is a complementary Diels-Alder reactive moiety relative to Y D and is a dienophile when Y D is a diene, and vice versa; L′ is independently in each occurrence NHR 2 —, [imidazole-R 2 ], HS—, HO—, R 3 OOC—, C(R 2 ) 2 ═CR 2 —, R 1 ═CH—HC═CR 3 , OCN—, XOC—(X═Cl, Br, I), R 2 ≡C—, N 3 ; R 5 is a nullity, C 1 -C 30 alkyl, C 2 -C 30 alkenyl, or C 6 -C 24 aryl; and Z is or L′-R 4 —Y A —Y D —R 4 -M-L- where Z is coupled to a second polymer subunit.