Synthesis and Investigation of a Photoswitchable Copolymer Deposited via Initiated Chemical Vapor Deposition for Application in Organic Smart Surfaces

Abstract

The deposition of well-defined photochromic thin films is highly attractive but challenging when it comes to practical applications. In conventional wet chemistry methods, the choice of potential monomers and substrates is restricted to compatibility with the solvent. In addition to this, reversible photoisomerization of a photochromic compound covalently bound in a solid film can be hindered by chain interactions within the polymer matrix. After establishing a method to co-sublime solid chromophores in our previous work, we now present the successful copolymerization and detailed investigation of initiated chemical vapor deposition (iCVD)-prepared films of hydroxyethyl methacrylate (HEMA) cross-linked with a photoswitchable diazocine. The all-dry character of iCVD enabled the combination of a hydrophobic photochromic unit with a highly hydrophilic co-monomer without phase separation or defect formation, independent of the solubility of the used precursors. The so produced thin films stand out for their fast response upon irradiation with blue light, which minimizes the risk of photodegradation, as well as by full recovery of their stable resting state with a green light or mild heating. Finally, we demonstrate the deposition of our films on different materials such as glass or flexible polymeric substrates and present a straightforward approach for patterned coatings with a shadow mask. Using a conventional blue laser to induce photoswitching, it was possible to create accurate patterns in real time proving the applicability of our films in fields such as smart surfaces, labeling, or data storage.

ARGET ATRP of Methyl Acrylate and Methyl Methacrylate with Diazocine-Derived Initiators

“…The E → Z thermal relaxation kinetics of the diazocine-centered polymeric chains depended greatly on the presence of the solvent and on the polymer matrix (glassy/rubbery) in the solid state, especially when strong electronic effects from substituents on the diazocine aromatic ring were absent. Our diazocine-containing elastomers qualify as potential candidates for the use in optical waveguides, data storage, , and photopatterning. ,, …”

“…We further studied the photochromism of diazocine incorporated in high-molecular-weight acrylate and methacrylate polymer chains in both solution and in the solid state. Polymers containing photochromic units in the main chain serve in potential photonic applications such as optical waveguides, data storage, , and photopatterned surfaces. ,, …”

“…Polymers containing photochromic units in the main chain serve in potential photonic applications 31 such as optical waveguides, 32 data storage, 33,34 and photopatterned surfaces. 10,35,36 ■ EXPERIMENTAL SECTION Materials. α-Bromoisobutyryl bromide (BIBB, 98%, Sigma-Aldrich), N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA, Merck), tris [2-(dimethylamino)ethyl]amine (Me 6 TREN, synthesized according to the procedure by Ciampolini and Nardi), 37 and triethylamine (anhydrous, Fluorochem) were degassed by three freeze−pump−thaw cycles and stored in the glovebox.…”

Triplet-Sensitized Bidirectional Isomerization of Bridged Azobenzene

“…Diazocines also exhibit more efficient photoswitching using longer excitation wavelengths and possess higher quantum yields. [1][2][3][4][5][6][7][8][9][10][11][12][13] As a result, diazocines have found use in emerging fields, such as stimuli-responsive systems, [14][15][16][17][18][19] , photoactuation, 20 and most notably, photopharmacology [21][22][23][24][25][26][27][28] . Unlike conventional azobenzene, whose triplet state properties have been investigated since the 1960s, 29 no studies on the triplet states of diazocine molecules have been published.…”

Lichtgesteuerte Konstruktion und Zerstörung: Schaltung zwischen zwei unterschiedlich zusammengesetzten käfigartigen Komplexen

“…[14c] Kürzlich wurden Diazocine (verbrückte Azobenzole) als neue Art von Photoschaltern mit vielversprechenden Eigenschaften für Anwendungen entwickelt, die von der Photopharmakologie [18] bis hin zu schaltbaren Oberflächen [19] und intelligenten Materialien reichen. [20] Die gute Trennung der n-π*-und π-π*-Banden, die effiziente Photoschaltung mit sichtbarem Licht und die thermodynamische Stabilität der Z-Konfiguration (im Gegensatz zur E-Konfiguration bei Azobenzolen) machen Diazocine für die Entwicklung photoschaltbarer Käfige interessant. Die Synthese von photoschaltbaren Käfigen auf Diazocinbasis steht jedoch noch in den Anfängen.…”