Surface photografting initiated by benzophenone in water and mixed solvents containing water and ethanol

Abstract

Photografting reactions are usually carried out in organic solvents due to the water insoluble nature of photoinitiators such as benzophenone (BP). This work reports the effect of water and mixed solvents containing water and ethanol on the surface photografting of methacrylic acid (MAA) onto polyethylene initiated by BP. The percent grafting increased with the increase of water volume ratio in the mixed solvent, and BP showed the highest photoinitiation efficiency when dissolved in pure water solvent. Effects of BP concentration, monomer concentration, and monomer type on photografting were studied. The percent grafting showed the maximum at a lower BP concentration (0.20 mol/mol %) in pure water solvent than that (0.60 mol/mol %) in the mixed solvent with 90 v/v % water. The percent grafting first increased with the increase of monomer concentration till 3 mol L À1 and then decreased. Acrylic acid (AA) could also be photografted onto polyethylene by BP in the mixed solvents. UV-visible spectroscopic examinations revealed that the k max of p-p* transitions of BP red shifted as the increase of the water volume ratio, i.e., the polarity of the solvent. The excitation of BP in solvents with a higher polarity under UV irradiation requires less energy, so the photografting initiated by BP is easier to occur.

Hydrophilic modification of SLA 3D printed droplet generators by photochemical grafting

“…Other graing techniques used higher powered light sources to avoid deaerating the graing solution. 37,38,41 Tretinnikov et al placed a quartz cover directly on their graing solution placed on the part, creating a very small volume of solution and simultaneously preventing continuous oxygen diffusion into it. 37 The cover eliminated the need for deoxygenation.…”

Probing multivalency in ligand–receptor-mediated adhesion of soft, biomimetic interfaces

“…The observed increase in grafting density of MA over AA is well established in the literature [13,17–18]. For example, Yang et al [17] compared the grafting density of MA and AA on low density polyethylene (LDPE) films through measuring the weight increase of the film.…”

Random photografting of polymers to nanoparticles for well‐dispersed nanocomposites

“…Validation of this choice is provided by experiments on solutions of small‐molecule analogs, as summarized in Supporting Information Figure S7. We note that although BP has been widely used to modify chemistry of solid surfaces, we are aware of only one study related to attaching polymers to NPs . In that case, polymers were grafted to BP‐coated NPs in the solid state, which requires that particles be well dispersed prior to grafting; otherwise, the result will be highly crosslinked NP aggregates.…”