Enhanced photo-reactivity of polyanthracene in the VIS region.

The wavelength-dependent photo-reactivity of polyanthracene was explored upon UV-C and VIS light irradiation. The material was prepared via one-pot chemical oxidation route using FeCl3 as oxidizing agent. A decrease in surface hydrophobicity of a polyanthracene-coated poly(methylmethacrylate) substrate from 109.11° to 60.82° was observed upon UV-C exposure for 48 hrs which was attributed to increase in oxygen content at the surface, as validated by energy dispersive X-ray spectroscopy. Upon exposure to ultraviolet-visible LEDs, photo-dimerization of polyanthracene in solution occurred and was monitored using UV-VIS spectroscopy. The photo-dimer product formation decreased from 381 nm to 468 nm and was found to be higher for the polyanthracene material compared to the monomer anthracene. At 381 nm, photo-dimerization of the material was found to be approx. 4x more efficient than the non-substituted monomer counterpart. Results obtained show that photo-dimerization of polyanthracene will proceed upon exposure with visible light LEDs with reduction in efficiency at longer wavelengths. To compensate, irradiation power of the light source and irradiation time were increased.

Photo-Controlled [4+4] Cycloaddition of Anthryl-Polymer Systems: A Versatile Approach to Fabricate Functional Materials.

The reversible photo-induced [4+4] cycloaddition reaction of anthracene enables multiple cycles of dimerization and scission, allowing phototunable linkage of molecular fragments for the synthesis of polymer scaffolds. New functional materials ranging from hydrogels to shape-memory polymers were designed from anthryl-polymer systems because of their diverse photochemical reactivity and responsiveness. Light as an external stimulus allows for the remote and precise spatiotemporal control of materials without the need for additional reagents. Depending on how the photoreactive anthracene moieties were introduced, the interaction of anthryl-polymer systems with light results in various processes such as polymerization, cyclization, and cross-linking. Structural modifications of anthracene derivatives could shift their absorption from the ultraviolet to the visible light region, widening their range of applications including biologically relevant studies. These applications are further diversified and enhanced by the reversibility of the dimerization reaction using light and heat as stimuli. In this review, current developments in the synthesis and photodimerization of anthracene-containing polymers and their emerging applications in the fabrication of new materials are discussed.

Exploring the corrosion inhibition capability of FAP-based ionic liquids on stainless steel.

Corrosion is clearly one of the more common causes of materials failure in stainless steel. To manage corrosion, chemical inhibitors are often used for prevention and control. Ionic liquids due to their hydrophobic and corrosion-resistant property are being explored as alternative protective coatings and anti-corrosion materials. In this particular study, ionic liquids containing functionalized imidazolium cations and tris(pentafluoroethyl)trifluorophosphate (FAP) anions were investigated for their ability to inhibit corrosion on stainless steel surfaces in acidic environment. Using surface characterization techniques, specifically scanning electron microscopy and energy-dispersive X-ray (EDX), the morphology and the elemental composition of the steel surfaces before and after corrosion were determined. Contact angle measurements were also performed to determine how these ionic liquids were able to wet the stainless steel surface. In addition, potentiodynamic studies were carried out to ensure that corrosion inhibition has occurred. Results show that these ionic liquids were able to inhibit corrosion on the stainless steel surfaces. This indicates promise in the use of these FAP-based ionic liquids for corrosion management in stainless steel.