the present invention is a rheology - modifiable polymeric composition . the resulting rheology - modified 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 through a free - radical trapping species . suppressing the undesirable degradation or carbon - carbon crosslinking reaction and permitting the desirable coupling reaction yield a rheology - modified polymer .