Investigação teórica das condições de síntese por inversão de fase de suportes esponjosos de polimetilmetacrilato para membranas de grafeno aplicáveis à dessalinização

Abstract

Reverse osmosis, the main and most efficient desalination method available today, is a process that requires energy-intensive pumps. The reduction in energy consumption of this process involves the development of more efficient membranes, such as graphene membranes. If they achieve their best performance, they will be able to promote energy savings of up to 15 %. The graphene used to make these membranes is produced by chemical vapor deposition on a copper substrate and, later, transferred to a polymeric support. For graphene membranes to reach the market, the improvement of transfer methods and the characteristics of these polymeric supports are examples of advances still needed. Aiming to contribute to the development of polymeric supports, the objective of this work was to study the phase inversion of poly(methyl methacrylate) and determine the best conditions for the synthesis of spongy supports for graphene membranes from this polymer. Papers that reported obtainingpolymeric membranes with a sponge-like or finger-like (macroporous) structure from the phase inversion of pure poly(methyl methacrylate) were searched in the literature. For each of the synthesis conditions presented in these works, the value of Φ was calculated, the predictive index of the membrane structure obtained by phase inversion from the polymer, solvent and non-solvent solubility parameters. In addition, the value of Φ’ was calculated, the index proposed in this dissertation to predict the structure of membranes obtained by phase inversion in systems with surfactant. The values of Φ and Φ’ were analyzed using statistical tools such as confidence intervals and hypothesis tests. The results found indicate that the phase inversion of poly(methyl methacrylate) to obtain sponge-like structures must be carried out in systems whose Φ value is less than 0.22 or the Φ’ value is greater than 0.55. It was possible to conclude from the results found that both the Φ index and the Φ' index can differentiate at some level poly(methyl methacrylate) phase inversion systems that generate sponge-like structures from those that generate finger-like structures.