Robust UV-Curable Antimicrobial Polymeric Coatings for Medical Plastics Prepared by Controlled Radical Polymerization

In response to hospital acquired infections stemming from biofilms and the impending antibiotic resistance crisis, the development of non-traditional, non-leachable antimicrobials have gained significant traction. Contact-active antimicrobial coatings physically attached to surfaces with cationic active sites, such as ammonium and phosphonium, are of particular interest in the prevention of pathogenic bacterial transfer. Previously reported antimicrobial coatings are found to be susceptible to abrasion, significantly limiting their potential applications. In this work, a range of robust, antimicrobial polymeric coatings synthesized by control radical polymerization are presented. Polymeric thin film coatings possessing cationic groups with n-alkyl substituents of n ≤ 4 demonstrated antimicrobial properties against gram-positive bacteria, while species containing bulkier substituents were biologically inactive, contradictory of previously reported monomeric coatings. Cationic polymeric brush coatings were found to have a higher antibacterial activity against the gram-positive model compared to its non-brush equivalent, but failed against the gram-negative model. These polymeric thin films demonstrate the complexity of antimicrobial coating designs and facilitates the investigation into the architecture of these coatings.

Robust UV-Curable Antimicrobial Polymeric Coatings for Medical Plastics Prepared by Controlled Radical Polymerization

In response to hospital acquired infections stemming from biofilms and the impending antibiotic resistance crisis, the development of non-traditional, non-leachable antimicrobials have gained significant traction. Contact-active antimicrobial coatings physically attached to surfaces with cationic active sites, such as ammonium and phosphonium, are of particular interest in the prevention of pathogenic bacterial transfer. Previously reported antimicrobial coatings are found to be susceptible to abrasion, significantly limiting their potential applications. In this work, a range of robust, antimicrobial polymeric coatings synthesized by control radical polymerization are presented. Polymeric thin film coatings possessing cationic groups with n-alkyl substituents of n ≤ 4 demonstrated antimicrobial properties against gram-positive bacteria, while species containing bulkier substituents were biologically inactive, contradictory of previously reported monomeric coatings. Cationic polymeric brush coatings were found to have a higher antibacterial activity against the gram-positive model compared to its non-brush equivalent, but failed against the gram-negative model. These polymeric thin films demonstrate the complexity of antimicrobial coating designs and facilitates the investigation into the architecture of these coatings.

Synthesis of Optically Tunable and Thermally Stable PMMA–PVA/CuO NPs Hybrid Nanocomposite Thin Films

We report the synthesis and comprehensive characterization of polymethylmethacrylate (PMMA)/polyvinylalcohol (PVA) polymeric blend doped with different concentrations of Copper oxide (CuO) nanoparticles (NPs). The PMMA–PVA/CuO nanocomposite hybrid thin films containing wt.% = 0%, 2%, 4%, 8%, and 16% of CuO NPs are deposited on glass substrates via dip-coating technique. Key optical parameters are measured, analyzed, and interpreted. Tauc, Urbach, Spitzer–Fan, and Drude models are employed to calculate the optical bandgap energy (Eg) and the optoelectronic parameters of PMMA–PVA/CuO nanocomposites. The refractive index and Eg of undoped PMMA–PVA are found to be (1.5–1.85) and 4.101 eV, respectively. Incorporation of specific concentrations of CuO NPs into PMMA–PVA blend leads to a considerable decrease in Eg and to an increase of the refractive index. Moreover, Fourier Transform Infrared Spectroscopy (FTIR) transmittance spectra are measured and analyzed for undoped and doped polymeric thin films to pinpoint the major vibrational modes in the spectral range (500 and 4000 cm−1) as well as to elucidate the nature of chemical network bonding. Thermogravimetric analysis (TGA) is conducted under appropriate conditions to ensure the thermal stability of thin films. Doped polymeric thin films are found to be thermally stable below 105 °C. Therefore, controlled tuning of optoelectronic and thermal properties of doped polymeric thin films by introducing an appropriate concentration of inorganic fillers leads to a smart design of scaled multifunctional devices.

Synthesis, Optical, Chemical and Thermal Characterizations of PMMA-PS/CeO2 Nanoparticles Thin Film

We report the synthesis of hybrid thin films based on polymethyl methacrylate) (PMMA) and polystyrene (PS) doped with 1%, 3%, 5%, and 7% of cerium dioxide nanoparticles (CeO2 NPs). The As-prepared thin films of (PMMA-PS) incorporated with CeO2 NPs are deposited on a glass substrate. The transmittance T% (λ) and reflectance R% (λ) of PMMA-PS/CeO2 NPs thin films are measured at room temperature in the spectral range (250–700) nm. High transmittance of 87% is observed in the low-energy regions. However, transmittance decreases sharply to a vanishing value in the high-energy region. In addition, as the CeO2 NPs concentration is increased, a red shift of the absorption edge is clearly observed suggesting a considerable decrease in the band gap energy of PMMA-PS/CeO2 NPs thin film. The optical constants (n and k) and related key optical and optoelectronic parameters of PMMA-PS/Ce NPs thin films are reported and interpreted. Furthermore, Tauc and Urbach models are employed to elucidate optical behavior and calculate the band gaps of the as-synthesized nanocomposite thin films. The optical band gap energy of PMMA-PS thin film is found to be 4.03 eV. Optical band gap engineering is found to be possible upon introducing CeO2 NPs into PMMA-PS polymeric thin films as demonstrated clearly by the continuous decrease of optical band gap upon increasing CeO2 content. Fourier-transform infrared spectroscopy (FTIR) analysis is conducted to identify the major vibrational modes of the nanocomposite. The peak at 541.42 cm−1 is assigned to Ce–O and indicates the incorporation of CeO2 NPs into the copolymers matrices. There were drastic changes to the width and intensity of the vibrational bands of PMMA-PS upon addition of CeO2 NPs. To examine the chemical and thermal stability, thermogravimetric (TGA) thermograms are measured. We found that (PMMA-PVA)/CeO2 NPs nanocomposite thin films are thermally stable below 110 °C. Therefore, they could be key candidate materials for a wide range of scaled multifunctional smart optical and optoelectronic devices.

Carbon Monoxide Sensing Technologies

The book covers the sensing and monitoring of poisonous carbon monoxide pollution in the environment. The sensors covered include semiconducting metal oxides, carbon nanotubes, conducting polymeric thin films, sensors based on colorimetric detection, non-dispersive infrared sensors, electrochemical sensors and photoacoustic detectors.