In an effort to contribute significantly to the progress of current separation science and related monolith technology, the objectives of the proposed studies are to prepare and to characterize highly efficient and retentive photopolymerized organic-silica hybrid monolithic capillaries each having a nanolayer of photografted polymer coating. In these types of porous monolithic materials the benefits of monoliths will be combined with straightforward UV-initiated surface modification with a wide variety of functional groups. This novel approach allows for simple and fast preparation of separation media with diverse chemistries that are not otherwise achievable and therefore provides opportunities for improved and innovative separations.
The unique bimodal pore structure of monoliths provides enhanced properties in terms of separation performance and selectivity at low column back pressure thus enabling fast and high throughput analyses. Currently available hybrid monoliths are known for their good mechanical stability and well-defined porous properties. In this study we propose to employ photografting for surface modification. This technique represents a fast and simple UV-initiated approach that enables polymerization, creating branched and crosslinked architecture. As a result, the homogeneous distribution of the polymer nanolayer permits highly efficient shielding of the residual silanol groups and therefore enhanced hydrolytic stability of the hybrid monolith. In addition, this process benefits from the commercial availability of monomers with various functionalities. As a consequence preparation of highly efficient and retentive separation media with diverse surface chemistry permits a wide range of separation mechanisms and selection variety of applications.
Monoliths will be prepared inside UV-transparent fused silica capillary columns. Capillary liquid chromatography will be utilized for the assessment of the separation performance of capillaries and it will be a direct measure of the surface coverage with the polymer nanolayer. The properties of the prepared capillaries will be evaluated by means of a model set of tests with respect to retention, efficiency, permeability, and reproducibility, mechanical, thermal and pH-range stability. These newly prepared capillaries will then be compared to the characteristics of columns of similar efficiency. Various techniques, such as scanning electron microscopy and nitrogen porosimetry, will be used for the structural characterization and the measurement of the physico-chemical properties of the pores.
A study in which the physico-chemical characteristics and the chromatographic performance of a series of monoliths each with a photografted nanolayer of one of a variety of polymer coatings is proposed. More specifically, photopolymerized organic-silica hybrid monoliths with various photografted fluorinated functionalities will be fabricated and and their suitability for reversed-phase separation of analytes of wide range of polarities, and closely related, and halogenated compounds will be determined. This design establishes a foundation for the development of fast, simple and efficient chemical modifications. Selection of surface chemistry permits the preparation of separation media for reversed-phase, anion- or cation-exchange, chiral recognition, or more refined forms of chromatography.
In a broader scope, this proposed model warrants selection of a variety of organic monomers with different functional groups for the preparation of monolithic stationary phases with diverse surface chemistries to function in a wide range of separation mechanisms. Applications such as chromatographic separations, heterogeneous catalysis, and solid phase extraction that rely on interactions with a solid surface will greatly benefit from the introduction of multiple functionalities.
This project represents the continuation of an existing collaboration with the Organic and Macromolecular Facility at the Molecular Foundry User Facility at the Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA. This project will be mainly executed at Barry University and partially at LBNL. Barry University is a federally designated Hispanic-Serving and Minority-Serving Institution of higher education with a student body that is 67% female. Undergraduate science majors will gain hands on experience under the direct mentorship of the PI. Involvement in research will broaden their education and will significantly contribute to their scientific growth. The results will be disseminated through the presentations at scientific conferences and in the form of publications in scientific journals related to the proposed topic
