Mohammed Qasim Mohammed

2016 AFPGR Participant


 Patterned electrode surfaces for sensing applications

About Mohammed
Mohammed is a PhD student in the department of Chemistry, supervised by Professor A. Robert Hillman and Professor Karl S. Ryder. Profile portrait image
About My Research

Polymers have become an important part in our daily lives due to a multitude of applications from phones to artificial hearts. In the past, researchers decades ago, their conducting properties were discovered. From that time, research and studies have been launched with the aim of improving the conductivity and the stability of these polymers and finding new applications in various areas of life. They have become a successful alternative for many materials used in for example chemical sensors, corrosion inhibitors, solar cells, electronics, batteries, actuators, and in the field of medical engineering. New possibilities which have offered by conductive polymers have enabled them to revolutionize these applications. Recently, there has been growing interest in developing patterned polymer surfaces to make 2D spatially heterogeneous films surface with diverse chemical functionalities. The pattern strategy is the technique to fabricate the pattern of surface film or pattern functional polymers with micrometer to nanometer scales. A considerable number of strategies can be used to pattern a conjugated polymer film such as photolithography, direct writing techniques, printing techniques, and particle beam lithography. These patterned surfaces have diverse functions such as altering their properties and structure when exposed to a certain stimulus and recognition of different species in different solution analytes. The improvements of surface polymer films have enabled these polymers to be used in many applications including microelectronic, high selectivity sensors, solar cells, drug delivery and catalysis. Recent studies has been demonstrated an ability of pattern technique to design and develop polymers and has paved the way for many new applications. The interests in patterned polymers have originated from the variety of synthetic and biological polymers, and the ability to ‘design’ new class of polymers. Micro-patterned conductive polymers are attractive materials with a number of distinctive characteristics including their ability on changing of chemical properties of the polymers by altering of the monomer units.

Research Findings

The concept of electroactive functionalised surfaces which containing receptor sites suitable for recognizing and undergoing redox chemistry with solution phase analytes is well-established. Receptor charge state and polymer film conductivity can be controlled via the applied potential and the analytical measurand is current, which is in turn related to solution reactant concentration.

This study successfully generated films of two derivatives of pyrrole; (3-(pyrrol-1-yl) propanoic acid”PyCOOH” and 3-(Pyrrol-1-yl) propylamine “PyNH2”) through electropolymerization in electrolyte solution using the cyclic voltammetry with varying scan rates. Then, the protection of amino and carboxylic acid groups was performed by using Fluorenylmethyloxycarbonyl chloride (Fmoc) and Pentafluorophenol (Pfp) groups, respectively. The next step is polymerization of new monomers which contained the protected groups using cyclic voltammetry. Characterization and behaviours of all films were studied and monitored using electrochemical techniques including cyclic voltammetry and chronoamperometry. The ester and amide films were hydrolysed to create voids (volume free) in the polymer films to accommodate the new receptor units with maintaining the polymer film from collapse. This method will allow to good spatial control and new method to manipulation of surface properties. The films chemical structures (before, during protection and after hydrolysis) were monitored by using Fourier Transform Infrared spectroscopy (FTIR). In addition, Electrochemical Quartz Crystal Microbalance (EQCM) was used to determine the mass changes associated with film deposition and redox cycling. Furthermore, morphology of films determined using 3D optical microscopy, Scanning Electron Microscope (SEM) and Atomic-Force Microscopy.

Future Work
  1. Identify suitable receptor(s) and accomplishment their immobilization throughout the polymer film.
  2. Assay the degree of functionalization gravimetrically and spectroscopically.
  3. Explore, implement and establish the spatial resolution of lateral patterning procedures.
  4. Apply the patterned surface to solution phase recognition and analysis.

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