Kinetic Modelling of the Synthesis of Polycarboxylate Ethers Via Partial Esterification of Acrylic Copolymers

Objective: In this work, the synthesis of polycarboxylate ethers (PCE) via partial esterification of acrylic copolymers has been experimentally carried out with the aim of obtaining results useful to the development of a reliable kinetic model.

Method: Experimental tests were conducted starting from monomethyl ether polyethylene glycol (MPEG) as side chain, and two acrylic backbones of different constitution. The reactions were carried out in a 350 mL batch reactor made of glass. Thirteen PCE polymers have been produced varying the target esterification degree (15–45%), reaction temperature (150–180°C) and time (60–460 min).

Results: The results of degree of MPEG conversion, obtained through gel permeation chromatography, have been fitted with different kinetic models through a devoted software and procedure. The model resulting in a very satisfying fitting was based on a kinetic equation of pseudo 1st-order with respect to the MPEG concentration, and pure 1st-order with respect to the concentration of carboxylic groups. Once the kinetic parameters have been determined, the model has been validated against experimental data obtained under different and additional operating conditions in terms of esterification degree and operating temperature.

Conclusion: The good fitting with the experimental data of MPEG conversion under the new operating conditions witnesses the soundness of the proposed approach.