Molecular-level interactions of an azopolymer and poly(dodecylmethacrylate) in mixed Langmuir and Langmuir–Blodgett films for optical storage

Abstract

a b s t r a c tThe applicability of azopolymers in optical storage can be extended through the use of nanostructured films produced with the Langmuir-Blodgett (LB) technique, but the film properties need to be optimized since these polymers generally do not form stable Langmuir films to be transferred onto solid substrates. Here, photoinduced birefringence was investigated for mixed Langmuir-Blodgett films from the homo-0 -nitroazobenzene (HPDR1-MA) and poly(dodecylmethacrylate) (HPDod-MA). The interactions between these polymers were studied in Langmuir and LB films. Surface pressure-area isotherms pointed to molecular-level interactions for proportions of 51 mf%, 41 mf% and 31 mf% of HPDR1-MA. Phase segregation was not apparent in the BAM images, in which the morphology of the blend film was clearly different from that of the Langmuir films of neat homopolymers. Through PM-IRRAS, we noted that the interaction between the azopolymer and HPDod-MA affected the orientation of carbonyl groups. Strong interactions for the mixture with 41 mf% of poly(dodecylmethacrylate) led to stable Langmuir films that were transferred onto solid supports as LB films. The photoinduced birefringence of 101-layer mixed LB films show features that make these films useful for optical storage, with the advantage of short writing times in comparison to other azopolymer films.

Optical storage in azobenzene-containing epoxy polymers processed as Langmuir Blodgett films

“…Upon turning the writing laser off at point B, the signal decayed to almost zero for the LB film, while for the SC film some remnant birefringence was observed. This result was not expected based on the literature, as the remnant birefringence is normally higher for LB films owing to the close packing of the azochromophores attached as side groups [16]. It seems that for the present results, the same factors inducing high mobility in LB films, leading to faster writing processes and higher birefringence, allow for a complete randomization of the azochromophores after the laser was turned off.…”

Effect of molecular architectures in photoinduced birefringence in films of azo-modified diblock copolymers

“…In addition, the maximum birefringence (Dn) for 10-layer LB and LS films (Dn = 0.115 and 0.101, respectively) was almost double the value for the spin-coated film (Dn = 0.058). The enhanced birefringence for LB and LS films is consistent with data in the literature [7,[23][24][25] and has been attributed to the ordered nature of nanostructured films built in a layer-by-layer fashion [23,26]. The residual birefringence, on the other hand, was higher for the SC film that retains 72% of the maximum signal after the writing laser was turned off, to be compared with 45% for LB and LS films.…”

Vibrational analysis of [4-[(E)-phenylazo] phenyl]ethanol based on the comparison between the experimental and DFT calculated Raman spectra

“…Because of their unique characteristics [1] (spread over air-water interface [2,3], disperse into porous materials to form hybrid organic-inorganic composites [4][5][6], graft onto polymers chains [7][8][9] or onto inorganic materials and surfaces [10][11][12][13]) azobenzene and its derivatives have been of great interest over the past two decades. The azobenzene derivatives which exhibit photoisomerization from the thermodynamically more stable trans isomer to the cis isomer (and vice versa) by irradiation with UV or visible light were extensively studied for their photochemical properties in solution [1,14] and therefore for their ability to produce photochemical devices [16][17][18].…”