Maryam Babaie - Novel Drug Delivery Systems Dept., Iran Polymer and Petrochemical Institute, Tehran, Iran
Mohammad Imani - Novel Drug Delivery Systems Dept., Iran Polymer and Petrochemical Institute, Tehran, Iran.
Hamed Azizi - Novel Drug Delivery Systems Dept., Iran Polymer and Petrochemical Institute, Tehran, Iran.
Farzad Lahoti - Fard - Novel Drug Delivery Systems Dept., Iran Polymer and Petrochemical Institute, Tehran, Iran.

In this study, pH-induced changes in chain conformation of a methacrylate terpolymer i.e., poly(dimethylaminoethyl methacrylate-co-methyl methacrylate-co-butyl methacrylate) is followed as a function of mono (acetic acid) or dicarboxylic acids concentration. The polymer was dissolved in a solvent mixture comprising acetone, ethanol and 1-propanol. Dicarboxylic acids were also selected as a homologous series including oxalic, succinic and adipic acid. Reducedviscosities were determined using a capillary viscometer and used to determine chain conformation parameters using Fuoss model. It was observed that using acetic acid, tertiary aminefunctional groups on the polymer backbone was protonated by reducing pH values to values lowerthan 7.28 which in turn cause an increment in repulsive forces induced by electrostatic charges. These repulsive forces will expand the polymer coil helix. Intramolecular crosslinking was observed using dicarboxylic acids when polymer concentrations were much lower than C* values

Polymer, Chain conformation, pH, Carboxylic acids, Dilute solution viscometry