Polyurea microcapsules with a photocleavable shell: UV-triggered release

Abstract

We report the preparation and characterization of photocleavable polyurea microcapsules. First, an isocyanate end functionalized oligomer, bearing the photolabile 6-nitroveratroyloxycarbonyl group was synthesized. This oligomer, in combination with diethylenetriamine, was then utilized in the preparation of polyurea microcapsules. Polyurea microcapsules (50-300 m), loaded with a hydrophobic dye solution and consisting of a dense capsule shell were prepared via an interfacial polymerization in a stable oil-in-water emulsion system. Thanks to the intra-molecular photocleavage mechanism, the UV-triggered rupture of the photocleavable capsule shell occurred both in solution and in solid state, leading to the successful release of the encapsulated liquid core.2

Pharmacological aspects of release from microcapsules — from polymeric multilayers to lipid membranes

“…This process was interpreted as rearrangement of PAzo polymers in the polymeric network; similar processes were also observed for microgels [65]. Photocleavable polyurea can be another candidate for UV based release [66]. For non-biological applications the use of UV-light [67] represents an interesting alternative.…”

Photo-responsive polymer nanocapsules

“…6 displays the absorption peak at 320 nm, which is assigned to the π-π* transition of the azobenzene electron system of the E form. 30 The peak absorbance decreased with increasing irradiation time, indicating the occurrence of the E to Z isomerization of the azobenzene moiety. In the case of NT05, a 20% decrease of absorbance occurred in 36 min, while a change of less than 5% was displayed by NM1, indicating a lower photosensitivity of NM1 capsules.…”

“…[27][28][29] Light induced activation offers an outstanding advantage, since it can be M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT applied externally with high precision and enables the solid-state release even in absence of solvent. 30 Among light-triggered systems, in this work we focused on UV-light responsive polymeric capsules, characterized by the presence of azobenzene moieties as building blocks of a lightly cross-linked polyamide shell. The ability of azo-compounds to undergo reversible E-Z isomerization is widely known, 31 and they have been used in a various range of applications.…”

Recent Approaches for Designing Nanomaterials-Based Coatings for Corrosion Protection

“…The sharp innovation in nanotechnology is one of the main reasons for the development of "smart" functional coatings which can be used for a variety of applications including antifogging [1] and anti-icing coatings [2][3][4], scratch-resistant coatings [5][6][7], anti-stain coatings [8,9], moisture-resistant coatings [10][11][12], oil-repellent coatings [13,14], self-cleaning coatings [15][16][17], antimicrobial coatings [18][19][20][21][22], UV protection coatings [23,24], adhesive coatings [25], and anticorrosive self-healing coatings [26][27][28][29][30][31][32][33][34][35][36][37].…”