the present invention is a rheology - modifiable polymeric composition or a free - radical crosslinkable polymeric composition , wherein the resulting rheologymodifying bond or crosslinking bond is a thermally - reversible bond . the resulting polymer is prepared from at least one polymer which upon forming free radicals preferentially degrades or carbon - carbon crosslinks . the present invention permits suppression of the preferential reaction while permitting the polymer to be coupled or crosslinked through a thermally - reversible bond . suppressing the undesirable degradation or carbon - carbon crosslinking reaction and permitting the desirable reaction yield a rheology - modified polymer or a free - radical thermally - reversibly crosslinked polymer .