Sensitive nanohydrogels were prepared via surfactant free emulsion copolymerization of N-vinylcaprolactam and poly(ethylene glycol) methyl ether methacrylate, and either N-vinylpyrrolidone (VP) or 2-methacryloyloxybenzoic acid (2MBA) to adjust the transition temperature (T-tr). The crosslinker ethylene glycol dimethacrylate was used for the polymer network construction. The resulting nanohydrogel sizes are between 120 and 300 nm. -Parameter, obtained from light scattering studies, suggests that core-sell nanogels of flexible chains were obtained. T-tr increases with increasing comonomer content (VP or 2MBA) and decreases with decreasing pH for 2MBA containing nanohydrogels. Nanohydrogels containing 15.5% of 2MBA exhibit T-tr close to 38 degrees C. Nanogels are able to control the release of the loaded antineoplastic drug 5-fluorouracil. For the prepared T/pH-sensitive nanogels, the release is slower at pH 7.4 and 37 degrees C than at tumor conditions: pH 6 and 40 degrees C. Mathematical models were applied to evaluate the kinetics of drug release; Peppas model fitted best indicating a Fickian diffusion trough a sphere. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2662-2672