ELBL films

FIG. 14.8 Diffraction efficiency versus time while an SRG was being inscribed on a spin-coated side-chain azobenzene (CH-IA-CA) polymer film.The efficiency is seen to decrease when the film is coated vdth an ELBL film of poly(diallyl dimeti iammpnium chloride) (PDAC) alternated with suifonated polystyrene (SPS), whose molecules do not undergo transtrans isomerization. For an ELBL with 20 biiay-ers, the efficiency dropped considerably, and practically no SRG could be inscribed. From reference 55. 

FIG. 14.9 Sur ce modulation for an SRG against the number of bilayers (PDAC/SPS) in an ELBL film deposited on the spin-coated CH-1A-CA azopolymer film. From reference 55. 

It has been demonstrated that photobleaching and photodegradation can play an important role on the SRG formation on ELBL films. " These results will be discussed separately when the influence of film architecture is analyzed in Section 14.4.9. 

One can note some discrepancies in the literature. Some researchers have reported no dependence on polarization for ablation or photodegradation, but for ELBL films there was some dependence, though not as strong as in SRGs originating from light-driven mass transport. In addition, the phase of the SRG appears to be different in distinct papers. Egami et and Che et... 

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