Surfactant Molecular Assemblies In The Light Of The Isomerization Reaction

Photoisomerization of trans-stilbene (TS) is investigated in sodium dodecylsulfate (SDS)/ benzyl alcohol (BA) / H2O systems in order to investigate the relationship between the reaction yields and the compositions and structures of molecular organized assemblies. The results show that the reaction yields in SDS/BA/H2O microemulsions and liquid crystals are larger than in benzyl alcohol and the yield in microemulsions is irrelative to SDS content but relative to BA and H2O contents; it is increased with the increase of H2O content or with the decrease of BA content. Compared with the microemulsions, liquid crystals are worse media for this reaction.The photosensitized isomerization of TS by 9,10-anthracenedicarbonitrile is investigated in SDS/BA/H2O systems in order to investigate the relationship between the reaction rates and the compositions and structures of the molecule organized assembly systems, and hence optimize the reaction medium. The results show that the reaction yields in liquid crystals and microemulsions showing O/W and bicontinuous structures are larger than in benzyl alcohol and the hexagonal liquid crystal is the best medium for this reaction. Moreover, the yield for cts-stilbene (CS) is relative to the content of BA, H2O and SDS; it is increased with the increase of H2O content or with the decrease of BA content and SDS content.At the weight ratio of Triton X-100/H2O being 16/84, the reaction yield of the direct photoisomerization of TS in Triton X-100/H2O micelle is a little lower than that in Triton X-100/n-C5H11OH/H2O microemulsions, and with the increase of the n-C5H11OH content, the reaction yields have a decrease. In the Triton X-100/ n-C5H11OH/H2O systems, the reaction yield is increased with the increase of H2O content or with the decrease of Triton X-100 content.At the weight ratio of n-C5H11OH/H2O being 4/1, the contents of surfactants(CTAB, SDS, DTAB) were changed separately in order to prepare the different W/O microemulsions. The reaction yield of the direct photoisomerization of TS in DTAB/ n-C5Hi,OH/H2O W/O microemulsions is higher than that in CTAB/n-C5HuOH/H2O W/O microemulsions, SDS/n-C5HiiOH/H2O W/O microemulsions and 1-pentanol. In those four different media, the %CS in CTAB/n-C5HnOH/H2O W/O microemulsions is the worst medium. CTAB and DTAB are cationic surfactants. Compared with the case in CTAB microemulsions, DTAB/n-C5HnOH/H2O W/O microemulsions is the better media for the reaction. But DTAB/n-CsHnOH/H2O W/O microemulsions is not a good media for the photosensitized isomerization of TS by 9,10-anthracenedicarbonitrile. The yield of the photosensitized isomerization of TS by 9,10-anthracenedicarbonitrile is largest in SDS/n-C5HnOH/H2O W/O microemulsion.Among the reaction yields in SDS, DTAB and Triton X-100 micelles, the %CS of the direct photoisomerization of TS is highest in DTAB/H2O micelle. At the weight ratio of surfactants/H2O being 16/84 and the weight ratio of n-C5H11OH being 1.0%, the reaction yields in those three different types of microemulsion are all increased, if comparing with cases in three corresponding micelles. Then they have a little decrease with the further increase of n-C5H11OH content.