(6bt) Polymers, Colloids and Composites: In the Service of Chromatography with New Porous Materials

Authors: 
Lamprou, A., Lawrence Berkeley National Laboratory

Polymer Science, Colloid Science and Chromatography can be interfaced during the development of functional materials for particular applications.

During my doctoral studies in ETH Zurich, I developed a new procedure towards macroporous polymeric microparticles. The major novelty of this procedure is that the porous structure is created and controlled without a template, through the controlled aggregation and coalescence of latex nanoparticles.

These macroporous particles were packed into chromatographic columns and functionalized via controlled radical polymerization with polymer chains of variable composition. Thus, different chromatographic modes were addressed, namely ion-exchange, as well as temperature-responsive chromatography, which relies on an unconventional separation mechanism. Several classes of compounds have been successfully separated, such as small pharmaceuticals, peptides, proteins and monoclonal antibodies. This whole procedure, from the preparation of the base macroporous material, to functionalization, to chromatographic application, has been recently secured by two patents.

Diverging from this project, I also became interested in different approaches for controlling the stability latex nanoparticles. To this end, I synthesized a set of block-copolymer surfactants via controlled polymerization and studied first their self-assembly behavior in an aqueous solution. Subsequently, these surfactants were applied in order to control the shear-induced aggregation of commercial latexes, which is an important issue in the recovery of polymers from a dispersed state.

In my postdoctoral research in Lawrence Berkeley National Lab, I developed porous polymeric monoliths in a thin-layer format for the efficient thin layer chromatographic (TLC) separation of proteins, peptides and fatty acids. Their pore surface was modified either with an in-house synthesized polymer or with metal nanoparticles of different noble metals, namely gold and silver, starting from the corresponding colloidal dispersion. All applied modifications provide a dual function: appropriate modulation of chromatographic interactions, coupled with the assistance in the desorption/ ionization of the separated compounds by a laser beam. The latter allowed the analytes detection by MALDI Mass Spectroscopy immediately after separation, without the use of an additional “matrix” substance, which needs to be conventionally applied.  

Recently I have initiated a project for the preparation of a composite porous monolith in a capillary format, modified with a layer of a metal-organic framework (MOF), aiming to the liquid-phase separation of small molecules. MOF are an advanced class of porous materials, composed of metal centers interconnected by organic linkers. They are currently intensively investigated, owing to their unique combination of high porosity, ultra-high surface area and tailorable structures. Thanks to their versatility, a range of different interactions between MOF and molecules that can enter their porous network can be potentially exploited for multiple applications, including separations. Nevertheless, little attention has been devoted so far to liquid-phase separations.

Apparently, supports with the appropriate porous structure are necessary, where the MOF can reside. Furthermore, procedures for the controlled formation of the MOF in the confined interior of such a porous support need to be developed, ensuring that it is properly anchored and it also exhibits structural integrity. After resolving those issues, analytical-scale separations can be addressed. As soon as the MOF scalability is tackled, preparative-scale applications could be feasible as well. Since this is an emerging field, I anticipate this type of studies to extent into the future and I hope to be able to undertake them as an independent investigator.

I therefore wish to create a research program, encompassing the following overlapping areas: (i) Developing porous polymeric or composite materials with defined pore structure and surface chemistry that can perform efficient chromatographic separations of biologically relevant compounds, (ii) Understanding and controlling the stability of colloidal systems, such as dispersions of polymer and metal nanoparticles, for both fundamental and applied purposes, (iii) Studying the self-association of polymers with tailored composition into structures, which can be utilized for multiple applications, such as structure templating and encapsulation.

Concerning my teaching and mentoring experience and vision, I have been a teaching assistant in undergraduate chemistry laboratory courses for three years. I have also supervised more than 10 undergraduate interns, assisting my research work. I have indeed learned a lot by working with younger colleagues; I enjoy the challenge of instilling motivation and inspiration for science in people with different personalities. As my scientific background is broad, I feel confident with undertaking teaching duties in several areas, within an engineering or a natural sciences curriculum. Such lectures could include Polymer Science & Engineering, Colloid & Interface Science, Analytical Chemistry, Separation Science & Technology and related subjects.