Azo-polysiloxanes spontaneous surface relief grating by pulsed laser irradiation

摘要

In the herein paper, the possibility of obtaining spontaneous surface relief gratings (SSRGs) on azo-polymeric film surfaces, using a single laser beam of 1.13 mJ energy in pulse mode, was investigated. Chain rigidity is essential to have SSRG of reasonable quality so three azo modified polymers, with different main-chain rigidity, were considered: poly(chloromethyl styrene) (PCMS), a linear polysiloxanes and a cyclic polysiloxane. The AFM studies on azo-polysiloxanes revealed unregulated networks with amplitudes of only 1 nm, while on PCMS orderly SSRGs were observed. These results showed that the more rigid azo-polymer, PCMS, had better capacity to generate SSRGs of high quality. The SSRG periodicity was correlated with the number of laser pulses, i.e. higher pulse number led to lower periodicity. The SSRGs formation was associated with polymeric chains self-organization favoured by photo-fluidisation.