| dc.description.abstract | Zwitterions contain both positively and negatively charged moieties in a molecule, which have received much attention because of their unique properties of superhydrophilicity, excellent anti-biofouling properties and diverse structural combinations. In particular, zwitterionic carboxybetaine materials (CBs) attract particular interests from worldwide due to their dual functionalities for antifouling and functionalizable properties with biomolecules to become a functional biointerface. However, a careful molecular design for the zwitterionic structure is needed to ensure the full exploitation in many applications under various distinct conditions. Previous findings showed that carboxybetaine monomers with two-carbon spacer between carboxylate and quaternary ammonium underwent elimination in a basic solution. Once eliminations occur, materials will lose their zwitterionic characteristics, leading to loss of desired antifouling properties. Therefore, the stability of CB materials is very important for long-term applications. In this work, we present a new molecular design to investigate stability of zwitterionic carboxybetaine-based polymers with attempt to avoid the elimination. The elimination reaction originates from the fact that protons adjacent to carbonyl groups are more acidic than other protons due to the hydrogen’s acidity of the β carbon. As a result, in this work, a hydrogen group is substituted by a methyl group in the intercharge arm, which is the carbon space between two charged groups, to afford β-substituted methyl carboxybetaine acrylamide (β-CB-2). In this study, we synthesized polyβ-substituted methyl carboxybetaine acrylamide (polyβ-CB-2) brushes on substrates via surface-initiated atom transfer radical polymerization (SI-ATRP). We applied contact angle goniometer, X-ray photoelectron spectroscopy (XPS), and atomic force microscope (AFM) to examine the hydrophilicity, the elemental compositions and roughness for the surfaces. The bacterial adhesion tests, protein adsorption tests and 3T3 fibroblast cell adsorption tests were conducted, showing the antifouling ability of the materials. Subsequently, we challenged the stability of the material under the basic surroundings. The results showed that Zaitsev elimination occurred to polyβ-CB-2 films, leading to loss of the fouling resistance against the adsorption of bacteria, proteins and fibroblast. In the contact angle and XPS measurements, changes in the elemental compositions on the surfaces and hydrophobic characteristic happened. Consequently, the goal of this study is to understand a structure-property relationships of CBs on the molecular level, which is valuable for the molecular design for demanded requirements. | en_US |