Photoreactive Nanoparticles as Nanometric Building Blocks for the Generation of Self‐Healing Hydrogel Thin Films

Abstract

The use of reversible photo-cross-linkable nanoparticles as nano building blocks for the formulation of nanostructured self-healing thin hydrogel films is shown for the first time. This strategy for the fabrication of autonomous self-healing coatings consisted of various microgels bearing surface cinnamate moieties. The nanoparticles were formed by miniemulsion copolymerization, which was followed by surface functionalization with the cinnamate groups. These nanoparticles were then used to form films by drop-casting, followed by interparticle photo-cross-linking polymerization through the light-induced forward dimerization reaction of the previously incorporated cinnamate groups. The reversibility of this macroscopic network formation was also demonstrated by photoinducing the backward dimerization reaction and carrying out several cycles of photoinduced cross-linking and de-cross-linking. The self-healing ability through swelling of these films following surface damage was also demonstrated. Finally, the ability of these self-healing macroscopic films to incorporate additives of different chemical nature before photo-cross-linking was evaluated.

Different synthetic pathways of nanoparticle-cored dendrimers (NCDs): Effects on the properties and their application as redox active centers

“…Thus, the highest dispersability and stability is achieved for the system where dendrons are attached to the particle surface through a flexible linker or spacer ( NCD‐2 ) enabling a much better solvation of the dendritic moiety, which then helps to stabilize the entire system. This effect is comparable to the steric stabilization of microgels due to the solubilization of the dangling chains on their surfaces . Unlike NCD‐2 , NCD‐1, and NCD‐3 bear exactly the same amount of dendrons covalently attached directly to the NPs' surface.…”

“…All intermediates and final products were fully characterized by TGA, TEM, and UV‐Vis and IR spectroscopy. The DRIFT method was used since it has been previously shown to be a powerful technique to gain better insight into the chemical composition at the surface and/or the outer part of NPs …”

Light‐Responsive Polymer Membranes

“…Photodimerization is an interesting photoreversible reaction for its applications as photoresists, self‐healing materials, nanocarriers, and responsive polymers . In addition, dimerizations can be considered green chemistry reactions because photons do not leave residues and reactions can take place at room temperature and even in the solid state …”

UV-reversible chain extendable polymers from thymine functionalized telechelic polymer chains

“…Recently, significant attention has been paid to the preparation of polymeric materials that enable the reversible tuning of molecular weights and crosslink densities of polymers. Reversible polymers are of interest for applications in self‐healing and reorganizable materials . Reversible polymeric systems rely either on covalent or noncovalent bonds .…”