C hapter 10 nanomaterial product Forms and Functions
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action. The photocatalysis process breaks down or oxidizes certain
materials in the presence of UV light. Common organic substances
are decomposed and loosened from the surface. Hydrophilic action
causes the water hitting the surface via rain or simple washing to
form into thin, flat sheets that in turn carry off the loosened organic
particles. This photocatalytic action was described in greater detail
earlier in this chapter. Of particular interest is that titanium oxide,
a substance long used in paints, possesses marked photocatalytic
properties when used as nanoparticles in the anatase phase. When
these are used in very thin coatings, the surface can be transparent.
Nanomaterials are also being used in paints to impart antimicrobial
or antibacterial properties to either kill or inhibit the development
of bacteria that cause common discoloration or staining. Antimicrobial qualities are also needed in paints in many settings to prevent
the spread of germs harmful to health. In common usage, antifungal
or antimold qualities are also included within the broad term antimicrobial. The enormous need for coatings of this type is described
earlier in this chapter, where several approaches to imparting these
qualities to paint are also described in detail. As discussed there,
one of the most common applications for paints again uses the
photocatalysis process, which oxidizes common organic substances
that form on a surface or are deposited on it. This action, in turn,
helps prevent staining, mold, and other problems.
Many paints containing nanoparticles can have multiple properties.
Hence many paints are claimed to be self-cleaning, antistaining, antibacterial, and antiscratching. Not all actions can be achieved with
equal efficiency simultaneously, but multiple functions can indeed
be achieved. Paints with multifunctional characteristics are being
developed extensively in the automobile industry with the intent
of making finishes glossier, harder, scratch resistant, and resistant
to various chemical substances found in everything from rain to
bird droppings (see Figure 10.36). For example, Mercedes-Benz has
used a nanoparticle clear coat for several years. Small ceramic particles are contained in a polymer matrix that forms a cross-linked
matrix when hardened under heat in an oven. The final paintwork
on an automobile body commonly consists of five layers, with a
total thickness of about 0.10 millimeters (100 micron). The first
layer is a zinc phosphate coating to protect the sheet metal from
corrosion and provide a basis for the subsequent cataphoretic dip
priming layer. The whole automobile body is submerged in a tank.
Next comes a filler layer that is electrostatically applied and that
has only a minor amount of organic solvent. Electrostatic charges
440
action. The photocatalysis process breaks down or oxidizes certain
materials in the presence of UV light. Common organic substances
are decomposed and loosened from the surface. Hydrophilic action
causes the water hitting the surface via rain or simple washing to
form into thin, flat sheets that in turn carry off the loosened organic
particles. This photocatalytic action was described in greater detail
earlier in this chapter. Of particular interest is that titanium oxide,
a substance long used in paints, possesses marked photocatalytic
properties when used as nanoparticles in the anatase phase. When
these are used in very thin coatings, the surface can be transparent.
Nanomaterials are also being used in paints to impart antimicrobial
or antibacterial properties to either kill or inhibit the development
of bacteria that cause common discoloration or staining. Antimicrobial qualities are also needed in paints in many settings to prevent
the spread of germs harmful to health. In common usage, antifungal
or antimold qualities are also included within the broad term antimicrobial. The enormous need for coatings of this type is described
earlier in this chapter, where several approaches to imparting these
qualities to paint are also described in detail. As discussed there,
one of the most common applications for paints again uses the
photocatalysis process, which oxidizes common organic substances
that form on a surface or are deposited on it. This action, in turn,
helps prevent staining, mold, and other problems.
Many paints containing nanoparticles can have multiple properties.
Hence many paints are claimed to be self-cleaning, antistaining, antibacterial, and antiscratching. Not all actions can be achieved with
equal efficiency simultaneously, but multiple functions can indeed
be achieved. Paints with multifunctional characteristics are being
developed extensively in the automobile industry with the intent
of making finishes glossier, harder, scratch resistant, and resistant
to various chemical substances found in everything from rain to
bird droppings (see Figure 10.36). For example, Mercedes-Benz has
used a nanoparticle clear coat for several years. Small ceramic particles are contained in a polymer matrix that forms a cross-linked
matrix when hardened under heat in an oven. The final paintwork
on an automobile body commonly consists of five layers, with a
total thickness of about 0.10 millimeters (100 micron). The first
layer is a zinc phosphate coating to protect the sheet metal from
corrosion and provide a basis for the subsequent cataphoretic dip
priming layer. The whole automobile body is submerged in a tank.
Next comes a filler layer that is electrostatically applied and that
has only a minor amount of organic solvent. Electrostatic charges