Stamp poly

Fig. 10 Generation of the patterned, sensitive monolayers using microcontact printing. a An amino-terminated monolayer on a glass surface is brought into contact with a poly(dimethylsiloxane) stamp inked with a fluorophore, resulting in the covalent attachment of the fluorophore to the amino-terminated monolayer (b). c Functionalization of the remaining free amino groups with reactive molecules...

The noncovalent adsorption of proteins by p.CP is experimentally simple, but suffers from the disadvantage that the attachment can be reversible by rinsing the pattern with certain buffers and detergents or replacement by other proteins in solution. Moreover, the orientation of the deposited protein is not controlled. Delamarche et al. proposed the use of stamps modified with poly(ethylene oxide) silanes.100 The modification was conducted by oxidation of the PDMS stamp and reaction with APTES to yield an amino-functionalized surface. The next step was the reaction with homobifunctional cross-linker BS3 to bind surface amino groups with poly(ethylene glycol) (PEG) chains (Fig. 14.10). 

When poly(ethylene oxide) (PEO) silane was grafted onto oxidized PDMS stamps it acts as a protein repellent layer. This property was utilized to design a flat stamp with regions that can attract proteins (nonmodified PDMS) and regions modified with PEO that have protein-repellent properties. The local modification of native PDMS was conducted by oxidation in 02-plasma with the application of a metal mask (areas that were covered by the mask were not oxidized and not modified). Proteins (immunoglobulin G, IgG) were transferred successfully to the glass substrates... 

The second approach has the advantage that it provides flexibility in the choice of means to perform the printing. Figure 10.14 shows a stamp with this construction, designed for plastic electronics applications [42]. It consists of a thin layer of PDMS on top of a sheet of polyimide. The relatively high in-plane modulus of the poly-imide prevents distortions that can frustrate registration. Its small thickness enables the stamp to be bent in a manner that facilitates printing. 

Electrostatic interactions between fibrils and a surface can be exploited to create micron-sized patterns of fibrils. Mesquida and colleagues (2005) used this approach to selectively deposit fibrils onto negatively charged stripes of mica that were exposed between alternating stripes of deposited cationic poly-L-lysine, as shown in Figure 9. The striped pattern was formed by directing poly-L-lysine through the channels of a polydi-methysiloxane (PDMS) stamp that was placed in contact with the mica surface. 

PVP is short for the polymer poly (vinyl pyrrolidone).1021 When PVP is left in the open air it absorbs around 15% of its weight as water from the air, such is its ability to cling to water molecules. It is also used in various personal care products like shampoos, toothpastes, and is the adhesive which has replace animal-based glues on envelopes and postage stamps. 

For example, poly(vinyl alcohol) (PVOH) finds application as an effective adhesive for paper products such as the old-fashioned postage stamps or envelopes. Licking the stamp or envelope flap causes the adhesive to become sticky because water plasticizes the PVOH and lowers the Tg below room temperature. On pressing the stamp to a piece of paper, the polymer chains can entangle and hydrogen bond with the cellulose in the paper. As the water... 

Fabrication of patterned magnetite films by soft lithography and thermal decomposition using Fe(acac)3 is also possible as described by Yang and coworkers . The modality to obtain such structures on gold substrates is illustrated in Scheme 8. The array size could be tuned by changing the dimension of patterns on poly(drmethylsiloxane) stamps, the concentration of Fe(acac)3 solution and the size of water droplets during the condensation process. 

Recycling of unwanted polymers is the best solution, and six types of plastics in common use are frequently stamped with identifying codes assigned by the Society of the Plastics Industry (Table 31.2). After sorting by type, the items to be recycled are shredded into small chips, washed, dried, and melted for reuse. Soft-drink bottles, for instance, are made from recycled poly(ethylene terephthalate), trash bags are made from recycled low-density polyethylene, and garden furniture is made from recycled polypropylene and mixed plastics. 

Fig. 23.11 Schematic depicting the stepwise fonnation of monolayers on a gold substrate by microcontact printing. (Top) A poly(dimethylsiloxane) (PDMS) stamp inked with one alkanethio-late is contacted with gold, forming a spatially-locahzed monolayer. (Bottom) The substrate is immersed in a second alkanethiolate, generating a monolayer of the second functionality [30]...

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