Articles
Stoichometry Of Complexes Formed Between EUDRAGIT® E PO And EUDRAGIT® L 100-55
January 16, 2009
•Poster: Stoichometry Of Complexes Formed Between EUDRAGIT® E PO And EUDRAGIT® L 100-55
By Evonik Röhm GmbH
The mixing of organic solutions of countercharged poly(meth)acrylates leads to complex formation. The characteristics of these complexes vary depending on the ratio in which the polymers are combined. Aim of this study was to quantify the precipitated complex at different ratios of EUDRAGIT® E PO and EUDRAGIT® L 100-55 and to determine its mechanism of formation.
Organic solutions (isopropanol: acetone = 60:40) of cationic (meth)acrylate copolymer EUDRAGIT® E PO with 50 % active groups and anionic copolymer EUDRAGIT® L 100-55 with 50 % active groups, were combined. The ratios were 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1 and 4:1 calculated on the molar ratio of functional groups. All polymers were supplied by Evonik Röhm GmbH, Darmstadt, Germany.
The anionic polymer was dissolved in 400 ml isopropanol/acetone mixture, then 100 ml cationic polymer solution were added, and vice versa. Also trials were conducted by adding 100 ml of each polymer at the same time to 300 ml of the organic solvents in the reactor. The final volume was 500 ml in each case and the concentration was 0.0032 g polymer/ml. The solutions were mixed in a Schmizo reactor at a constant temperature of 20 °C and 200 rpm stirring speed. The feeding rate was approximately 1.6 ml/min. After mixing the precipitated complex was separated from the solution by centrifugation (Labofuge A, Heraeus Christ GmbH) at 500 rpm for 10 minutes and dried at 60 °C to constant mass.
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