L-Lactide ring-opening polymerization: a multi-objective optimization approach through mathematical modeling

As industries move towards sustainable product development, biopolymers such as polylactide are gaining significant attention owing to their self-degradability and eco-friendliness. Therefore, a multi-objective optimization problem (MOOP) formulation to obtain high-performance polylactide concerning physicochemical properties is designed through mathematical modeling and solved using the Elitist Non-dominated Sorting Genetic Algorithm (NSGA II). The current work is focused on improving the polymer growth mechanisms with stannous octoate (catalyst) and 1-dodecanol (co-catalyst) by analyzing three different case studies using optimization approach. In the first study, the Pareto front for batch L-lactide ring-opening polymerization (L-ROP) with objective functions of average molecular weight, polydispersity index, and time is obtained. Further investigations on esterification, chain propagation and the ratio of monomer–catalyst and cocatalyst–catalyst is carried out. The optimized result using certain range of initial reagent concentrations is determined and one of the suitable Pareto optimal solution for case study 1 gives M_w = 610 kDa, PDI = 1.8, time = 100 s; case study 2 is M_w = 560 kDa, λ1/λ0 = 4300, λ0 = 70; case study 3 is M_w = 500 kDa, M/C = 33,800, ROH/C = 8.5. The neighboring optimal solutions in the Pareto front have been classified into 3 groups and the corresponding process parameters for the particular outcome are tabulated. Process modeling and optimization in close vicinity with appropriate experimental data are distinct aspects of this work to apply in industrial plant level.

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