@article{ko_truong_woo_dickey_hsiao_genzer_2021, title={Counterpropagating Gradients of Antibacterial and Antifouling Polymer Brushes}, volume={12}, ISSN={["1526-4602"]}, url={https://doi.org/10.1021/acs.biomac.1c01386}, DOI={10.1021/acs.biomac.1c01386}, abstractNote={We report on the formation of counterpropagating density gradients in poly([2-dimethylaminoethyl] methacrylate) (PDMAEMA) brushes featuring spatially varying quaternized and betainized units. Starting with PDMAEMA brushes with constant grafting density and degree of polymerization, we first generate a density gradient of quaternized units by directional vapor reaction involving methyl iodide. The unreacted DMAEMA units are then betainized through gaseous-phase betainization with 1,3-propanesultone. The gas reaction of PDMAEMA with 1,3-propanesultone eliminates the formation of byproducts present during the liquid-phase modification. We use the counterpropagating density gradients of quaternized and betainized PDMAEMA brushes in antibacterial and antifouling studies. Completely quaternized and betainized brushes exhibit antibacterial and antifouling behaviors. Samples containing 12% of quaternized and 85% of betainized units act simultaneously as antibacterial and antifouling surfaces.}, journal={BIOMACROMOLECULES}, publisher={American Chemical Society (ACS)}, author={Ko, Yeongun and Truong, Vi Khanh and Woo, Sun Young and Dickey, Michael D. and Hsiao, Lilian and Genzer, Jan}, year={2021}, month={Dec} }
 @article{woo_pandiyarajan_genzer_2021, title={Tuning the Properties of Surface-Anchored Polymer Networks by Varying the Concentration of a Thermally Activated Cross-Linker, Annealing Time, and Temperature in a One-Pot Reaction}, volume={3}, ISSN={["2637-6105"]}, DOI={10.1021/acsapm.1c00890}, abstractNote={We investigate the properties of surface-anchored polymer networks created via one-pot synthesis using thermally active 6-azidosulfonylhexyltriethoxysilane (6-ASHTES). 6-ASHTES is a bifunctional gelator that undergoes cross-linking and surface-anchoring reactions when annealed above 100 °C. We employ a poly(vinylpyrrolidone) (PVP) with different molecular weights (10–1300 kDa) as a model system to examine the effect of 6-ASHTES concentration, annealing time, and annealing temperature on gel formation. A thin film of PVP/6-ASHTES mixture is deposited on a clean silicon wafer and annealed to form network layers. Spectroscopic ellipsometry measures the film thickness of the cross-linked layers from which the gel fraction and swelling ratio are determined. The gel fraction of PVP in the network can be "dialed in" by varying the annealing time, temperature, and concentration of 6-ASHTES in the PVP/6-ASHTES mixture. We use a simple Monte Carlo simulation model to describe cross-linking as a function of cross-linker concentration, reaction rate, reaction time, and polymer length. The trends obtained from the model simulations are in qualitative agreement with the experimental data.}, number={11}, journal={ACS APPLIED POLYMER MATERIALS}, author={Woo, Sun Young and Pandiyarajan, C. K. and Genzer, Jan}, year={2021}, month={Nov}, pages={5568–5577} }