A degradable cross-linked polymer comprising a cleavable cross-linking group derived from a curing agent and an epoxy resin, wherein the curing agent comprises a compound of Formula I or a salt thereof: wherein n is an integer greater than 1; A is alkylene, alkylene-hetero-alkylene, alkenylene, alkenylene-hetero-alkenylene, alkylene-hetero-alkenylene, alkynylene, cycloalkylene, alkylene-cycloalkylene, alkylene-cycloalkylene-alkylene, alkenylene-cycloalkylene, alkenylene-cycloalkylene-alkenylen, alkylene-cycloalkylene-alkenylene, alkynylene-cycloalkylene, alkynylene-cycloalkylene-alkynylene, heterocycloalkylene, alkylene-heterocycloalkylene, alkylene-heterocycloalkylene-alkylene, alkenylene-heterocycloalkylene, alkenylene-heterocycloalkylene-alkenylene, alkylene-heterocycloalkylene-alkenylene, alkynylene-heterocycloalkylene, alkynylene-heterocycloalkylene-alkynylene, cycloalkenylene, alkylene-cycloalkenylene, alkylene-cycloalkenylene-alkylene, alkenylene-cycloalkenylene, alkenylene-cycloalkenylene-alkenylene, alkylene-cycloalkenylene-alkenylene, alkynylene-cycloalkenylene, alkynylene-cycloalkenylene-alkynylene, heterocycloalkenylene, alkylene-heterocycloalkenylene, alkylene-heterocycloalkenylene-alkylene, alkenylene-heterocycloalkenylene, alkenylene-heterocycloalkenylene-alkenylene, alkylene-heterocycloalkenylene-alkenylene, alkynylene-heterocycloalkenylene, alkynylene-heterocycloalkenylene-alkynylene, arylene, arylene-X-arylene, alkylene-arylene, alkylene-arylene-alkylene, alkenylene-arylene, alkenylene-arylene-alkenylene, alkylene-arylene-alkenylene, alkynylene-arylene, alkynylene-arylene-alkynylene, heteroarylene, heteroarylene-X-heteroarylene, heteroarylene-X-arylene, alkylene-heteroarylene, alkylene-heteroarylene-alkylene, alkenylene-heteroarylene, alkenylene-heteroarylene-alkenylene, alkylene-heteroarylene-alkenylene, alkynylene-heteroarylene, or alkynylene-heteroarylene-alkynylene; X is alkylene, alkenylene, oxygen, sulfur, nitrogen, sulfoxide, sulfone, carbonyl, -C O-, -OC O-, -OC NH-, -C NH-, or -HNC NH-; each B independently is hydrogen, alkyl, cycloalkyl, heterocyclic, heterocycloalkyl, alkenyl, cycloalkenyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, alkyl-hetero-alkyl, alkyl-hetero-alkenyl, or alkynyl; or, A and at least one B, together with the carbon atom to which they are bonded, form a saturated or unsaturated ring optionally containing at least one hetero ring atom of O, S, N, or P; or, at least two B groups, together with A and carbon atoms to which A and B groups are bonded, form a saturated or unsaturated ring optionally containing at least one hetero ring atom of O, S, N, or P; and wherein at least one amino group in the curing agent is fully reacted to lose both hydrogen atoms and form two bonds with the epoxy resin. n is an integer greater than 1; A is alkylene, alkylene-hetero-alkylene, alkenylene, alkenylene-hetero-alkenylene, alkylene-hetero-alkenylene, alkynylene, cycloalkylene, alkylene-cycloalkylene, alkylene-cycloalkylene-alkylene, alkenylene-cycloalkylene, alkenylene-cycloalkylene-alkenylen, alkylene-cycloalkylene-alkenylene, alkynylene-cycloalkylene, alkynylene-cycloalkylene-alkynylene, heterocycloalkylene, alkylene-heterocycloalkylene, alkylene-heterocycloalkylene-alkylene, alkenylene-heterocycloalkylene, alkenylene-heterocycloalkylene-alkenylene, alkylene-heterocycloalkylene-alkenylene, alkynylene-heterocycloalkylene, alkynylene-heterocycloalkylene-alkynylene, cycloalkenylene, alkylene-cycloalkenylene, alkylene-cycloalkenylene-alkylene, alkenylene-cycloalkenylene, alkenylene-cycloalkenylene-alkenylene, alkylene-cycloalkenylene-alkenylene, alkynylene-cycloalkenylene, alkynylene-cycloalkenylene-alkynylene, heterocycloalkenylene, alkylene-heterocycloalkenylene, alkylene-heterocycloalkenylene-alkylene, alkenylene-heterocycloalkenylene, alkenylene-heterocycloalkenylene-alkenylene, alkylene-heterocycloalkenylene-alkenylene, alkynylene-heterocycloalkenylene, alkynylene-heterocycloalkenylene-alkynylene, arylene, arylene-X-arylene, alkylene-arylene, alkylene-arylene-alkylene, alkenylene-arylene, alkenylene-arylene-alkenylene, alkylene-arylene-alkenylene, alkynylene-arylene, alkynylene-arylene-alkynylene, heteroarylene, heteroarylene-X-heteroarylene, heteroarylene-X-arylene, alkylene-heteroarylene, alkylene-heteroarylene-alkylene, alkenylene-heteroarylene, alkenylene-heteroarylene-alkenylene, alkylene-heteroarylene-alkenylene, alkynylene-heteroarylene, or alkynylene-heteroarylene-alkynylene; X is alkylene, alkenylene, oxygen, sulfur, nitrogen, sulfoxide, sulfone, carbonyl, -C O-, -OC O-, -OC NH-, -C NH-, or -HNC NH-; each B independently is hydrogen, alkyl, cycloalkyl, heterocyclic, heterocycloalkyl, alkenyl, cycloalkenyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, alkyl-hetero-alkyl, alkyl-hetero-alkenyl, or alkynyl; or, A and at least one B, together with the carbon atom to which they are bonded, form a saturated or unsaturated ring optionally containing at least one hetero ring atom of O, S, N, or P; or, at least two B groups, together with A and carbon atoms to which A and B groups are bonded, form a saturated or unsaturated ring optionally containing at least one hetero ring atom of O, S, N, or P; and wherein at least one amino group in the curing agent is fully reacted to lose both hydrogen atoms and form two bonds with the epoxy resin.