Morphological design and structure evaluation of poly(divinylbenzene) -based particles

This thesis focuses on advancing the synthesis of polydivinylbenzene (PDVB) microparticles via precipitation polymerization and swelling techniques, aiming to tailor their morphological features for enhanced applications, particularly in size exclusion chromatography (SEC).
The first part focuses on the synthesis of core-shell particles via precipitation polymerization, consisting of a non-porous core and a porous shell, intended as column material for SEC. Monodisperse, non-porous core particles were reliably produced using cost-efficient standard laboratory equipment in place of specialized devices. Next to shell growth, it could be shown that low-molecular-weight porogens common for suspension polymerization do not yield pores suitable for SEC in precipitation polymerization under the tested conditions. This could be explained by the lack of confined space during particle formation in precipitation polymerization. The synthesized particles proved effective for hydrodynamic chromatography (HDC) and can be used as size standards for analytical applications like particle size analyzers.
The second part presents an approach to PDVB particle synthesis by combining precipitation polymerization with a template-swelling technique. Three distinct strategies involving different polystyrene templates were explored, resulting in particles with intricate morphologies, including surface grooves and hollow cores. SEM analysis revealed the impact of template architecture on the particle morphology. The resulting particles with adjustable void sizes hold promise for various applications, like catalysis and delivery systems. This work provides a proof of concept, and future research may further extend control over the nanoarchitecture and explore other templating methods.
The third part explores an alternative route to create a porous shell on a highly crosslinked PDVB core particle, utilizing the template swelling method with macromolecular porogen aiming at pore sizes larger than 10 nm. The two-step swelling method sought to integrate the PS porogen into the precursor particle shells and subsequently remove it to leave behind the desired porous structure. However, despite successful incorporation of the PS template during the initial swelling stage, the subsequent removal of the porogen did not lead to the expected porous structure. Excessive, unintended crosslinking, possibly due to chain transfer reactions or residual double bonds in the PDVB system, appears to have hindered the removal of the PS template. While the procedure still seems promising, further research needs to be done to lower the crosslinking degree of the precursor particle shell.
The findings contribute to the ongoing efforts to enhance the versatility of PDVB particles for diverse applications, like for example for HDC chromatography or in the biomedical field, emphasizing the importance of combining and tailoring synthesis methods to achieve specific morphological features. Parts of this thesis were performed in collaboration with PSS GmbH, Mainz and LiNaCon Dr. Ingo Lieberwirth, Mainz.