Related Experiment Video
Updated: Jun 14, 2026
09:31
Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices
Published on: March 27, 2019
Quantifying surface-accessible quaternary charge for surface modified coatings via streaming potential measurements
Murari L Gupta1, Kennard Brunson, Asima Chakravorty
1Department of Chemical and Life Science Engineering, Virginia Commonwealth University, 601 West Main Street, Richmond, Virginia 23284, USA.
Langmuir : the ACS Journal of Surfaces and Colloids
|March 26, 2010
Summary
Polymer surface modifiers with quaternary charge show antimicrobial properties. Annealing and water immersion cause phase separation, reducing surface charge and antimicrobial stability.
Area of Science:
- Materials Science
- Polymer Chemistry
- Surface Science
Background:
- Polyurethanes with specific soft blocks (trifluoroethoxy and dodecylammonium-butoxy) are effective polymer surface modifiers (PSMs).
- These PSMs exhibit high contact antimicrobial efficiency, linked to surface quaternary charge concentration.
Purpose of the Study:
- To report streaming potential (SP) measurements for estimating accessible surface charge density in novel polymer coatings.
- To investigate the effects of annealing and electrolyte flow cycles on near-surface quaternary charge concentration.
- To correlate surface morphology changes with charge instability and antimicrobial property durability.
Main Methods:
- Utilized a novel cell design with fused-silica capillaries coated with polyurethanes (PU-1 and a base polyurethane).
- Performed streaming potential (SP) measurements to determine surface charge density and zeta potentials.
- Employed tapping mode atomic force microscopy (TM-AFM) to analyze surface morphology and phase separation.
Main Results:
- Neat PU-1 showed stable SP, increasing upon annealing, while 1 wt% PU-1 coatings exhibited SP attenuation over cycles.
- Annealing and even short water immersion of 1 wt% PU-1 coatings induced microscale phase separation.
- Morphological changes correlated with SP instability, suggesting sequestration of charge by a fluorous modifier-rich phase.
Conclusions:
- The study provides a facile method for screening polycation-based antimicrobial coatings for accessible charge density.
- Phase separation in PU-1 coatings leads to temporal instability of near-surface charge and antimicrobial properties.
- Understanding these morphological and charge dynamics is crucial for developing durable antimicrobial surfaces.
Related Concept Videos
01:29Potential Due to a Polarized Object
A neutral atom consists of a positively charged nucleus surrounded by a negatively charged electron cloud. When placed in an external electric field, the external electric force pulls the electrons and nucleus apart, opposite to the intrinsic attraction between the nucleus and the electrons. The opposing forces balance each other with a slight shift between the center of masses of the nucleus and the electron cloud, resulting in a polarized atom. On the other hand, a few molecules, like water,...
01:17Continuous Charge Distributions
Imagine a bucket of water. It contains many molecules, of the order of 1026 molecules. Thus, although it contains discrete elements (molecules) at the microscopic level, macroscopically, it can be considered continuous. Small volume elements of water, infinitesimal compared to the bulk of the bucket's volume, still contain many molecules. Under this framework, quantized matter is approximated as continuous for practical purposes.
The electric charge can also be subjected to an analogical...
The electric charge can also be subjected to an analogical...
01:17Controlled-Potential Coulometry: Electrolytic Methods
Controlled-potential coulometry, also known as potentiostatic coulometry, employs a three-electrode system in which the working electrode's potential is precisely regulated using a potentiostat. Platinum working electrodes are utilized for positive potentials, while mercury pool electrodes are favored for extremely negative potentials. The platinum counter electrode is separated from the analyte using a membrane or salt bridge to avoid interference in the analysis.
The chosen potential ensures...
The chosen potential ensures...
01:24Potential Due to a Magnetized Object
Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...
The vector...
01:06Interfacial Electrochemical Methods: Overview
Interfacial electrochemical methods focus on the phenomena occurring at the boundary between an electrode and a solution, as opposed to bulk methods that concentrate on the solution's overall properties. These interfacial methods are classified as either static or dynamic based on the presence of a nonzero current in the electrochemical cell and the consistency of analyte concentrations. Static methods, such as potentiometry, measure the cell's potential without any significant current passing...
01:26Electric Field at the Surface of a Conductor
Consider a conductor in electrostatic equilibrium. The net electric field inside a conductor vanishes, and extra charges on the conductor reside on its outer surface, regardless of where they originate.
In the 19th century, Michael Faraday conducted the famous ice pail experiment to prove that the charges always reside on the surface of a conductor. The experimental set-up consists of a conducting uncharged container mounted on an insulating stand. The outer surface of the container is...
In the 19th century, Michael Faraday conducted the famous ice pail experiment to prove that the charges always reside on the surface of a conductor. The experimental set-up consists of a conducting uncharged container mounted on an insulating stand. The outer surface of the container is...