Monolayer matrix, modification

Further modification of the above nanostructures is useful for obtaining new functional materials. Thirdly, we apply the dopant-induced laser ablation technique to site-selectively doped thin diblock copolymer films with spheres (sea-island), cylinders (hole-network), and wormlike structures on the nanoscale [19, 20]. When the dye-doped component parts are ablated away by laser light, the films are modified selectively. Concerning the laser ablation of diblock copolymer films, Lengl et al. carried out the excimer laser ablation of diblock copolymer monolayer films, forming spherical micelles loaded with an Au salt to obtain metallic Au nanodots [21]. They used the laser ablation to remove the polymer matrix. In our experiment, however, the laser ablation is used to remove one component of block copolymers. Thereby, we can expect to obtain new functional materials with novel nanostmctures. 

There are several reasons for the appeal of polymer modification immobilization is technically easier than working with monolayers the films are generally more stable and because of the multiple layers redox sites, the electrochemical responses are larger. Questions remain, however, as to how the electrochemical reaction of multimolecular layers of electroactive sites in a polymer matrix occur, e.g., mass transport and electron transfer processes by which the multilayers exchange electrons with the electrode and with reactive molecules in the contacting solution [9]. 

Figure 3.38 shows that reaction between Al(0H)3 and dicarboxylic acid anhydride affects the sedimentation volume of filler.The limiting value of sedimentation was obtained by modifying the filler surface with a monolayer of a suitable modifier. A similar modification affects the performance of this filler in polymer-filler composites. Thus, different properties were affected by the surface coverage of filler and by the filler-matrix interactions. 

Sudan 1 dye was extracted from chilli powder and detected using Au NPs in concentration as low as 48 ng in 1 g of powder (Cheung et al. 2010). Recently, Jahn and co-workers employed enzymatically generated Ag NPs prepared by a bottom-up and self-organizing procedure (see Sect. 3.4.2.1), in combination with a lipophilic sensor layer for the detection of water-insoluble azo-dye Sudan III in real food matrix, paprika products (Jahn et al. 2015). The surface modification consisted of self-assembled aliphatic hydrocarbons with a thiol moiety forming hydrophobic monolayer on the SERS substrate. The resulting layer repelled unwanted water-soluble analytes from the surface whereas water-insoluble ones were adsorbed and detected by SERS. The riboflavin was introduced as a water-soluble competitor, which is part of the relevant food matrices. Sudan 111 dye was detected down to 9 pmol 1 concentration from paprika powder extract in the methanol. Beside this, lipophilic sensor layer can also be applied for further analytical tasks for which it is beneficial to discriminate water-soluble from insoluble substances. 

---