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Polymethacrylate monoliths are synthetic adsorbents with macroporous and mesoporous interconnected channels that can be engineered to target the hydrodynamic features of a wide range of molecular species. However, rigorous study into the effect of synthesis conditions on their thermal stability is limited. This work attempts to characterise the influence of key synthesis process variables on the stability of polymethacrylate monoliths using thermogravimetric analysis at a heating rate of 10 °C/min. Experimental results showed that the thermal stability of polymethacrylate monoliths increased with decreasing polymerisation temperature from 85 to 65 °C. Increasing the total porogen (P) to monomer (M) ratio increased the thermal stability of the monolith by >62% and >50% for P40/M60–P60/M40 and P60/M40–P80/M20, respectively. The impact of the initiator concentration, monomer variation, biporogen ratio, washing and activation of the monoliths was investigated. Nuclear magnetic resonance analyses conducted confirmed the hydrolysis of epoxy moieties on the monolith. © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.

The thermo-molecular mechanisms associated with free radical synthesis of polymethacrylate monoliths offer an effective pathway to tune their pore characteristics. In this work, thermogravimetric analyses were used for ex situ characterization of polymethacrylate monoliths synthesised from ethylene glycol dimethacrylate (EDMA) and glycidyl methacrylate (GMA). Apparent activation energies of the polymeric monoliths were determined by using Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose (KAS) isoconversional methods. The number of degradation stages for the polymers were observed to be as follows: homopolymeric GMA and EDMA (2 degradation stages each) and polymeric EDMA-co-GMA monoliths (3 degradation stages). The relationship between apparent activation energy and extent of conversion showed that the degradation of monoliths is based on a complex multi-step reaction rather than a single reaction model. Kinetic parameters showed that an increase in the composition of EDMA and GMA above 20% significantly enhances the thermal stability of polymeric EDMA-co-GMA monoliths under elevated non-isothermal conditions. E40/G60 and E60/G40 monoliths were identified as the most thermally stable monoliths from the kinetic analyses. This article is protected by copyright. All rights reserved

Thermomolecular mechanisms associated with the synthesis of polymethacrylate monoliths are critical in controlling the physicochemical and binding characteristics of the adsorbent. Notwithstanding, there has been limited reported work on probing the underlining synthesis mechanism essential in establishing the relationship between in‐process polymerization characteristics and the physicochemical properties of the monolith for tailored applications. In this article, we present a real‐time thermochemical analysis of polymethacrylate monolith synthesis by free‐radical polymerization to probe the effects on the physicochemical characteristics of the adsorbent. The experimental results show that an increase in the crosslinker monomer concentration from 30 to 70% resulted in a peak temperature increase from 96.3 to 114.3 °C. Also, an increase in the initiator (benzoyl peroxide) concentration from 1 to 3% w/v resulted in a temperature increase from 90.7 to 106.3 °C. A temperature buildup increases the kinetic rate of intermolecular collision associated with microglobular formation and interglobular interactions. This reduces the structural homogeneity and macroporosity of the polymer matrix. A two‐phase reactive crystallization model was used to characterize the rate of monomeric reaction after initiation and microglobular formation from the liquid monomeric phase to formulate the theoretical framework essential for evaluating the kinetics of the polymer formation process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43507.