Abstract
Isopropyl acrylate‐2,3‐^14^C and isopropyl acrylate‐2,3‐^3^H were polymerized using anionic initiators. The isotactic polymers were fractionated by fractional precipitation and characterized. The polymer fractions were hydrolysed to polyacrylic acids by trifluoroacetic acid. Aqueous solutions of these radioactive labelled polyacrylic acids were injected intravenously to mice in amounts of 40 to 100mg/kg. Distribution in organs and the excretion were studied. About two thirds of the dose were excreted within the first two days with a half‐life of about 0,5 days. Further excretion took place with a half‐life of about six weeks. Distribution in the organism was not uniform; the highest concentrations were found in spleen, bones, and liver, i.e. organs being parts of the reticuloendothelial system. A relationship between organ concentration and molecular weight of the polyacrylic acid was only observed in the spleen. Nine weeks after injection about 10% of the dose were still retained in the organism, mainly in the skeleton.