Topic details
| Topic | Tailoring molecular dispersity in polymer brushes synthesized via the grafting-from approach |
|---|---|
| Supervisor | Ognen Pop-Georgievski, Ph.D. |
| Consultant | Assoc.Prof.RNDr. Ondřej Sedláček, Ph.D. |
| Department | Chemistry and Physics of Surfaces and Biointerfaces |
| Description | Polymer brushes have been widely used in controlling adverse interactions between artificial surfaces and biological media. However, the effects of the polymer chain’s dispersity constituting the brushes on various biological responses, such as the sorption (i.e., protein absorption within the brush structure and adsorption taking place at the distal ends) and the adhesion of bacteria and mammalian cells, remains an unexplored field. To address this, the thesis will develop a macromolecular toolbox for the synthesis of well-defined water-soluble linear polymers with controlled dispersity and molecular mass. These polymers will be grafted from the surface employing photo controlled surface initiated reversible addition-fragmentation transfer RAFT polymerization. The polymer dispersity will be tailored using defined mixtures of different RAFT chain transfer agents (CTAs) with different activities - 2-(butylthiocarbonothioylthio)propanoic acid for low dispersity, (2‐propionic acid) O‐ethyl xanthate or 2-[(diethylcarbamothioyl)sulfanyl]propanoic acid for higher dispersity. Thus, the polymer dispersity will be controlled by the ratio of both CTA types. Using the optimized polymerization protocols, the candidate will synthesize a library of hydrophilic polymers based on N-hydroxyethyl acrylamide (HEAM), N-Acryloylmorpholine (NAM) and/or N,N-dimethylacrylamide (DMAM), all of them leading to polymers with very low biofouling. Particular emphasis will be devoted to studying the molecular and physicochemical properties of the polymer brushes and the effects of the dispersity on the surface properties (e.g., molecular mass, grafting density, hydrophilicity, antifouling behavior) at constant average polymer length and/or polymer layer thickness. In particular, the polymer chains bound to planar surfaces will be analyzed by AFM-based single-molecule force spectroscopy (SMFS) by specifically pooling the individual chains through their designed distal ends. Additionally, the bound polymer chains (and in case of low amounts of polymer which can be obtained for the analysis, microparticles will be used) will be cleaved from the surfaces and analyzed by SEC, MALDI, and NMR. The cumulative layer properties, such as conformational state, chemical structure, covalent binding of proximal, i.e., anchoring groups, presence of reactive chain distal-end groups, swelling behavior and visco-elastic properties will be the particular focus of this thesis. A specific accent will be set on on unraveling the density profile and the chain end distribution within the polymer layers. |
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