Miscibility of physically and chemically non-uniform polymers
Stijn van Leuken defended his PhD thesis at the Department of Chemical Engineering and Chemistry on October 14th.
Polymeric materials are used in many aspects of modern society, particularly in plastics. With environmental and sustainability concerns growing, there is greater attention in relation to their use and how polymers are treated to make plastics. Often mixtures of polymers are encountered in processes during which solvents and additives, for example, are added. As there are numerous polymers, solvents, and additives available to produce materials, it would be great to be able to predict the outcome of a process before instigating a process. In his PhD thesis, Stijn van Leuken developed a theoretical framework to predict and describe the miscibility of non-uniform polymer mixtures to guide the rational development of polymeric materials.
There is an ever-increasing demand for polymeric materials in terms of quantities and feature optimization. At the same time, awareness of the environmental impact of plastics is growing.
Innovation of sustainable materials contributes to meeting this growing demand while lessening the environmental impact. The polymers in these materials are large molecules containing many subunits called monomers.
The size and chemical composition of the polymers in these materials varies. Polydispersity is a measure for this variation of polymers.
Environmentally friendly
Multi-component mixtures are present in every step of environmentally friendly material production and usage. Bio-based polymers, increasingly used as an alternative to fossil-based polymers, consist of chemically and physically polydisperse compounds.
Also, the unprocessed starting point of polymer recycling and disposal is a mixture of polydisperse polymers. During production processes polymers, solvents, additives, and fillers must be mixed or separated to minimize their environmental impact while maximizing their longevity and mechanical properties.
So non-uniformity plays an important role in the production and utilization of new polymeric materials.
Combinations
At the same time, the sheer number of potential variations and combinations makes experimentally or numerically studying every new mixture impractical. A direct predictive tool quantifying miscibility, solubility, and solvent absorption would provide a less time- and resource-consuming route to optimization.
The large number of equations for polydisperse mixtures makes using numerical techniques for polydisperse mixtures challenging. Therefore, chemical and physical polymer dispersity is often neglected in theoretical studies, although it significantly affects polymer-polymer and polymer-solvent miscibility.
For his PhD research, Stijn van Leuken developed a theoretical framework to predict and describe the miscibility of non-uniform polymer mixtures to guide the rational development of polymeric materials.
Predictions
Polymers can be dissolved in solvents and mixed to create new materials. Also, the durability of polycondensates is affected by water absorption.
Predictions of the solubility of polymers can be used to separate a subset of polymers from other polymers. In addition, predictions of the miscibility of polymers provide guide the choice of potential valuable polymers for polymer mixtures.
Van Leuken鈥檚 predictions of moisture uptake in polymer mixtures can be used to optimize the functionality and improve the durability of materials.
For the two-polymer types lignin and polyamides, he validated theoretical predictions with experimentally measured solubilities, miscibilities and solvent absorption.
Together, the presented techniques and quantifications contribute to the sustainable optimization of polymeric materials by predicting the miscibility of non-uniform polymers.
Title of PhD thesis: . Supervisors: Remco Tuinier, Rolf van Benthem, and Mark Vis.