Poly(methacrylic acid), p(MA), particles in the size range of nano and micrometer were prepared via emulsion and reverse suspension polymerization method, respectively. Ethylene glycol dimethacrylate (EGDMA) as a biodegradable cross-linker was used in the preparation of these p(MA) particles. Both nano and micrometer p(MA) particles were decorated with tannic acid (TA) via a direct esterification linkage upon activation of the carboxylic acid with N,N'-carbonyldiimidazole followed out by conjugation with TA to obtain p(MA)-TA. For the characterization of the particles TGA, FT-IR SEM, and light microscope were used. In vitro release of the TA from p(MA)-TA conjugates were investigated at pH 7.4 in phosphate buffered saline (PBS) by UV-vis spectrometer and result revealed that the amount of the used crosslinker has paramount significance in degradation of TA molecules. For example, p(MA)-TA microparticles with 1% of the crosslinking density released 83.24 mg TA per g particles in comparison to nanosizes p(MA)-TA particles with 10% of the crosslinking density that released 35.21 mg per g particles within four days. Additionally, antioxidant properties of all particles were evaluated by Total Phenol Content (TPC) and Trolox Equivalent Antioxidant Concentration (TEAC) methods and found that the p(MA)-TA microparticles has great antioxidant properties with TPC = 61.41 +/- 1.44 mgL(-1) gallic acid equivalent (GAE), TEAC = 248.82 +/- 1.96 mM trolox g(-1) for dry sample. (C) 2016 Elsevier B.V. All rights reserved.