Investigation of reversible photo-mechanical properties of azobenzene-based polymer films by nanoindentation

Light-triggered enhancement of mechanical properties and healing effect in azobenzene-based polymer films

“…Upon storage in the dark the stiffness decreased and after visible irradiation it reached a final value higher than the initial one. The observed changes of stiffness were expected to occur due to the photoisomerisation of azobenzene chromophores in the polymer and are in agreement with the literature [18]. In the following section we show the azobenzene isomerisation by UV/Vis spectroscopic analysis.…”

“…This suggests that maximum stiffness increase can only be achieved with 30% azobenzene loading. A previous study demonstrated a maximum of 10% increase of stiffness with 10% mol azobenzene loading [18].…”

“…A noteworthy nanoindentation study involving functional azobenzene/MMA random copolymer films containing 6% and 10% mol of chromophores demonstrated changes in the elastic modulus [18]. Upon exposure to UV irradiation the stiffness of the polymer film showed a notable increase by 10% and was attributed to trans to cis isomerisation of the azobenzene chromophore.…”

A Nanoindentation Study of Photo-Induced Changes in Polymers Containing Azobenzene

“…play an important role in determining the course of the photo-chemical reaction. It is widely accepted that alterations in the polymer network and phase changes in the material are reflected in the mechanical properties [12,13,[18][19][20][21][22]. A reversible photomechanical effect in an azobenzene containing polymer blend was explained by physical crosslinking and decrosslinking of the polymer chains [18].…”

Chemical and Physical Properties of Polyimides: Biomedical and Engineering Applications

“…For such practical applications materials besides of specific requirements viz the principal the presence of photochromic moieties, the thermal stability of orientation alignment, the high optical non-linearity, high damage threshold, chemical resistance, mechanical endurance, they should exhibit the high optical quality ability and feasibility of device fabrication which are determined in wide range by their solubility. Significant efforts have been made to improve solubility of polyimides by designing their structure [45].…”