Polymeric surface treatments

Polymeric surface treatments are applied in similar fashion, namely spin-coating from a low-concentration solution of the polymer in organic solvent, e.g. 0.1% (w/w) polymer in toluene. Spin conditions can vary widely but, as reported by 3M [30a], 500 rpm for 20 s then 2000 rpm for 40 s provides 100 A thick dry polymer films on smooth dielectrics with good surface quality and contact-angle uniformity. Spun layers are typically air-dried for several hours, or dried at an elevated temperature of 110-130 °C for 30 min in an oven or 5 min on a hot plate. These materials are typically not rinsed after they are baked, because the homopolymer version would redissolve, removing almost all of the polymer. In a recent report from Fris-bie s group, in collaboration with 3M, device oxides were intentionally roughened... 

Replacement of organic solvents with water, especially chlorinated solvents Aqueous emulsion polymerization to replace solvent-based polymerization Surface treatment (modification) process development for water-borne... 

Surface Modification. Plasma surface modification can include surface cleaning, surface activation, heat treatments, and plasma polymerization. Surface cleaning and surface activation are usually performed for enhanced joining of materials (see Metal SURFACE TREATMENTS). Plasma heat treatments are not, however, limited to high temperature equiUbrium plasmas on metals. Heat treatments of organic materials are also possible. Plasma polymerization crosses the boundaries between surface modification and materials production by producing materials often not available by any other method. In many cases these new materials can be appHed directly to a substrate, thus modifying the substrate in a novel way. 

Uses. /-Butyl hypochlorite has been found useful in upgrading vegetable oils (273) and in the preparation of a-substituted acryflc acid esters (274) and esters of isoprene halohydrins (275). Numerous patents describe its use in cross-linking of polymers (qv) (276), in surface treatment of mbber (qv) (277), and in odor control of polymer latexes (278). It is used in the preparation of propylene oxide (qv) in high yield with Httle or no by-products (269,279). Fluoroalkyl hypochlorites are useful as insecticides, initiators for polymerizations, and bleaching and chlorinating agents (280). 

While polymeric surfaces with relatively high surface energies (e.g. polyimides, ABS, polycarbonate, polyamides) can be adhered to readily without surface treatment, low surface energy polymers such as olefins, silicones, and fluoropolymers require surface treatments to increase the surface energy. Various oxidation techniques (such as flame, corona, plasma treatment, or chromic acid etching) allow strong bonds to be obtained to such polymers. 

Adhesion or printability of polymeric surfaces, including films, is often promoted by plasma or glow discharge treatment. In particular for apolar (low surface energy) surfaces such as polyolefins this is a commonly applied procedure. As a practical industrial example, the adhesion behaviour of polypropylenes after... 

This technique involves the dispersion of a nanomaterial in a monomer (Fig. 4.8). This step requires a certain amount of time that depends on the polarity of the monomer molecules, the surface treatment of the nanomaterial, and the swelling temperature. For thermoplastics, the polymerization can be initiated either by the addition of an agent or by an increase in temperature. For thermosets such as epoxies or unsaturated polyesters, a curing agent or peroxide can be added in order to initiate the polymerization. Functionalized nanomaterials can improve their initial dispersion in the monomer and consequently in the composites. In the case of layered materials, such as clays or graphene, the most important step is the penetration of the monomer between the sheets, thus allowing the polymer chains to exfoliate the material. The... 

Surface treatments of carbon fibers can in general be classified into oxidative and non-oxidative treatments. Oxidative treatments are further divided into dry oxidation in the presence of gases, plasma etching and wet oxidation the last of which is carried out chemically or electrolytically. Deposition of more active forms of carbon, such as the highly effective whiskerization, plasma polymerization and grafting of polymers are among the non-oxidative treatments of carbon fiber surfaces. 

It is important to emphasize that the surface layers of most polymeric materials are different from those of the bulk material and are often more susceptible to environmental attack. Thus, special surface treatments are often employed in an attempt to protect the surface molecules. 

Reactive surface treatment assumes chemical reaction of the coupling agent with both of the components. The considerable success of silanes in glass reinforced thermosets have led to their application in other fields they are used, or at least experimented with, in all kinds of composites irrespective of the type, chemical composition or other characteristics of the components. Reactive treatment, however, is even more complicated than non-reactive polymerization of the coupling agent, development of chemically bonded and physisorbed layers render the identification of surface chemistry, characterization of the interlayer... 

Another attempt by Tricas et al. to modify the surface of carbon black was by the plasma polymerization of acrylic acid [34]. Treatment with acrylic acid made carbon black hydrophilic. Plasma-coated carbon black was mixed with natural rubber and showed increased filler-filler interaction. The bound rubber content was reduced after the surface treatment of the filler. The authors also concluded that the surface of the carbon black was completely covered by the plasma polymer film, preventing the carbon black surface from playing any role in the polymer matrix. 

Flame is probably the oldest plasma known to humanity and flame treatment is one of the oldest methods used by industries for the modification of polymeric surfaces. Flame treatment is very often used to treat bulky objects. It is mainly employed to enhance the ink permeability on the polymer surface. Though a very simple set-up (comprising of a burner and a fuel tank) is required for this technique, a very high degree of craftsmanship is needed to produce consistent results. Oxidation at the polymer surface brought about by the flame treatment can be attributed to the high flame temperature range (1000-1500 °C) and its interaction with many exited species in the flame. For an efficient flame treatment, the variables like air-to-... 

Fig. 2.S. Su mmary of some of the shadow masking and surface-treatment results from 3M. A. Photograph of a polymeric aperture mask [30b] used to pattern a wide range of circuits. This mask bears a 6-inch x 6-inch deposition area, with high open aperture ratio. B. Photomicrograph taken of a one-bit RFID circuit patterned using the polymer shadow mask technology [30c], C. Internal clock signal and the externally demodulated rf, or reader signal of the circuit in B (carrier signal was 125...

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