Described herein is a mixture comprising: (a) a non-self-crosslinking polymer; and (b) a modifying compound comprising: (i) a first functional group capable of reacting with the reaction sites of the non-self-crosslinking polymer; and (ii) a second functional group capable of crosslinking with a curing agent, wherein the first functional group is different than the second functional group. Also, described are curable polymeric compositions, and methods of making cured polymeric compositions.