Publications by authors named "Kazi Sadman"
Article Synopsis
- Polyelectrolyte complex (PEC) materials are being optimized for use in membranes to improve separations and control fouling with the development of CMC- and QC+-functionalized variants for better antibacterial properties.
- Characterization techniques (FT-IR and H NMR) confirmed that the functionalized materials incorporated the desired chemical groups, with high substitution rates for CMC- and QC+.
- Testing demonstrated that these functionalized PECs had better stability, lower bacterial adhesion, and reduced fouling rates compared to unmodified materials, highlighting their potential for enhanced performance in filtration applications.
In this study, we present various examples of how thin film preparation for quartz crystal microbalance experiments informs the appropriate modeling of the data and determines which properties of the film can be quantified. The quartz crystal microbalance offers a uniquely sensitive platform for measuring fine changes in mass and/or mechanical properties of an applied film by observing the changes in mechanical resonance of a quartz crystal oscillating at high frequency. The advantages of this approach include its experimental versatility, ability to study changes in properties over a wide range of experimental time lengths, and the use of small sample sizes.
View Article and Find Full Text PDFQuantitatively understanding the self-assembly of amphiphilic macromolecules at liquid-liquid interfaces is a fundamental scientific concern due to its relevance to a broad range of applications including bottom-up nanopatterning, protein encapsulation, oil recovery, drug delivery, and other technologies. Elucidating the mechanisms that drive assembly of amphiphilic macromolecules at liquid-liquid interfaces is challenging due to the combination of hydrophobic, hydrophilic, and Coulomb interactions, which require consideration of the dielectric mismatch, solvation effects, ionic correlations, and entropic factors. Here we investigate the self-assembly of a model block copolymer with various charge fractions at the chloroform-water interface.
View Article and Find Full Text PDFVersatile and High-Throughput Polyelectrolyte Complex Membranes via Phase Inversion.
ACS Appl Mater Interfaces
May 2019
Article Synopsis
- High-flux filtration membranes that are both scalable and sustainable are needed for energy-efficient separations, but achieving this often poses challenges.
- This study presents a new method for creating polyelectrolyte complex (PEC) membranes using simple aqueous processing, allowing for control over their porosity and stability in various environments.
- PECs, made from oppositely charged polymers, can be swiftly synthesized and show great potential for both water and solvent filtration applications due to their enhanced electrostatic stability in organic solvents.
Guanidinium is one of nature's strongest denaturants and is also a motif that appears in several interfacial contexts such as the RGD sequence involved in cell adhesion, cell penetrating peptides, and antimicrobial molecules. It is important to quantify the origin of guanidinium's ion-specific interactions so that its unique behavior may be exploited in synthetic applications. The present work demonstrates that guanidinium ions can both break and form strongly associating ion complexes in a context-dependent way.
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- The resonance frequency of quartz crystal microbalance (QCM) relates to the mass on a sensor through the Sauerbrey expression, but this relationship becomes complex with thicker films, requiring a rheological model for analysis.
- Two viscoelastic models, the simple Voigt model and a power-law model, were evaluated for extracting properties of a thermoresponsive hydrogel film while varying temperature and film thickness.
- A framework for estimating physical properties of soft materials in the megahertz range was developed, outlining optimal film thicknesses for effective viscoelastic analysis using the QCM-D.
Article Synopsis
- Polyelectrolyte complex (PEC) films, made from oppositely charged polymers, have important uses in drug delivery, separation membranes, and biocompatible coatings.
- Traditional methods for creating these films are slow and complicated, requiring multiple steps to achieve desired thicknesses.
- This research introduces a fast one-pot electrochemical method to create 1 μm PEC films in just 5 minutes by utilizing hydrogen peroxide reduction, improving the efficiency and potential applications of PEC coatings.
The electrochemical quartz crystal microbalance (QCM) was used to investigate the deposition of poly(allylamine hydrochloride) (PAH) with molybdate anions under anodic conditions. The PAH-molybdate complex was used as a model system to understand possible deposition criteria which may be relevant to the formation of proteinaceous films on CoCrMo hip implants. Data indicate that PAH deposition will occur above ∼0.
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