Study of the nanostructuration capacity of some azopolymers with rigid or flexible chains

Abstract

Azobenzene polymers have been the subject of intensive research due to their unique and unexpected properties that allow various applications triggered by light. One of their attractive features is the possibility of changing the orientation of azobenzene chain through trans-cis-trans photoisomerization cycles to photoinduce birefringerence and linear dichroism in thin polymer films. The photochromic behavior and surface structuring capacity of rigid or flexible polymers having side azobenzene units have been investigated. The polyimides with side azobenzene units have rigid structure, while polysiloxane chains modified with azobenzene groups and nucleobases are considered materials with flexible structure. During the photochromic studies of the investigated polymers, a mechanism concerning the possibility to generate a fluid phase under UV/VIS irradiation was proposed. The photoisomerisation kinetic by UV-Vis irradiation in the solid state compared with the solution and the cis-trans azobenzene relaxation phenomena were presented. The surface structuring capacity of these polymers was studied using a Nd:YAG laser at 355 nm, at different incident fluencies and pulse numbers.

An atomic force microscopy statistical analysis of laser‐induced azo‐polyimide periodic tridimensional nanogrooves

“…Due to the diffraction phase mask, an interference pattern appears on the surface of the film. This periodical structure has the pitch of the same order of magnitude as the phase mask one (Sava et al, ). The irradiation conditions, namely the incident fluence and the number of irradiation pulses significantly influence the surface geometry of the polymer.…”

Thermal stability and optical properties of aromatic polyimides containing side-substituted azobenzene groups

“…Considering the previous studies related to the azobenzene containing polymers, the first decomposition stage situated in the range of 336-347 C can be attributed to the nitrogen elimination process from side azobenzene units. [20][21][22][23][24] The second and third decomposition stages can be attributed to the degradation of the macromolecular chain of the polymers, which is mainly present in aromatic imide structures, being known for their high thermal resistance to thermal degradation of these compounds. 9,10 A relatively high glass transition temperature (T g ) of these polymers have been obtained with values between 215 and 230 C, being useful in applications that demanded resistance at high temperatures.…”

Novel pendant azobenzene/polymer systems for second harmonic generation and optical data storage

“…push-pull azobenzenes. Countless polymer backbones [21][22][23] have been used as scaffolds for azo-moieties, as to endow certain physical properties. Several approaches [24][25][26] have been employed to embed suitable azo dyes in polymer matrices.…”