Thermal Stability and Decomposition Kinetics of Poly(3‐Methacryloylamido Propyl Trimethyl Ammonium Chloride‐Co‐Acrylamide)

Abstract

ABSTRACT Poly(3‐methacryloylamido propyl trimethyl ammonium chloride‐co‐acrylamide) (P(MAPTAC‐AM)) is extensively used under a variety of conditions. Herein, the thermal stability and decomposition kinetics of P(MAPTAC‐AM) samples with different intrinsic viscosities were evaluated using thermogravimetric analysis (TGA), as well as differential scanning calorimetry (DSC), under nitrogen atmosphere. Kinetic parameters were determined via model‐fitting Coats‐Redfern (CR) approach and the model‐free Flynn‐Wall‐Ozawa method. All samples showed three‐step mass loss: removal of adsorbed water/solvents, then two decomposition stages (20%–50% and 70%–90% conversion) separated by a plateau (50%–70%). Activation energy ( E ) increased with intrinsic viscosity, suggesting that higher molecular weight enhances thermal stability. CR analysis indicated first‐order reactions for both stages ( R 2 0.990–0.998). The pre‐exponential factor ( A ) was larger in Stage I than Stage II and decreased with molecular weight, revealing collision‐dominated degradation in Stage I versus bond vibration in Stage II. This work provides the first complete thermodynamic and kinetic parameter set for P(MAPTAC‐AM) across different molecular weights, establishes a quantitative E ‐[ η ] correlation, and distinguishes side‐chain (Stage I) from main‐chain (Stage II) scission. These findings fill a literature gap, support high‐temperature applications, and lay an experimental foundation for understanding the thermal decomposition mechanism of P(MAPTAC‐AM).