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02/15/2000
Killer Apparel and Bedding
We''re all familiar with rechargeable batteries but rechargeable
fabrics? Last year I saw predictions that in the new millennium
we would have new fabrics in clothing that wouldn''t need
cleaning and in germ-killing sheets. At the time, I was somewhat
skeptical about the claims. Now, of course, I find an article in the
January 2000 issue of Discover magazine that makes it all seem
quite feasible. The article deals with such things as Teflon suits,
phase-change fabrics and rechargeable killer clothing. Not only
that, but it looks like those ink-jet machines we discussed last
week might be used to produce custom fabrics.
Just the other day, I was wearing my 20-year old Majer 100%
wool slacks that won''t wear out and a couple drops of oil dripped
onto them from my pizza, which I shouldn''t have been eating
anyway. A trip to the cleaners is obviously in order. Teflon may
be the answer. Apparently, Teflon is now being used by some
manufacturers to coat individual fibers so that the staining fluids
from pizza and the like will just roll right off, cutting cleaning bills
appreciably. Actually, this could also be a boon for harried
parents who have to worry about their drooling and clumsy
offspring soiling their bibs and other apparel. However, I suspect
that Teflon would not find a market in diapers, where absorbency
is critical?
But the next item, phase-change fabrics, really grabbed my
attention. We''re all well acquainted with phase changes, the most
ubiquitous being the phase change from liquid water to solid ice
or vice versa. In your Scotch on the rocks, the phase change not
only helps to dilute the possible overly relaxing effect of the
alcohol but also serves to keep the drink at a pretty constant
temperature. The reason for this is that it takes heat to melt ice,
something known as the heat of fusion (melting). Conversely,
when water freezes, heat is given off in the same amount. So, if
you want to keep something at a constant temperature for a long
period of time, find a substance with a phase change at that
temperature. Textile engineers are trying to do just that in an
attempt to counter that offensive characteristic of humans trying
to adjust to temperature swings, sweating. Excuse me, I should
have used the more erudite term, perspiration.
About ten years ago, a waxy compound was developed which
turns from solid to liquid in just the right temperature range for
potential use in pilots'' gloves to keep their hands warm.
Unfortunately, cuts in the defense budget shelved the
development of this phase-change product. However, some
entrepreneurial types have taken this material and are marketing
boots and socks incorporating capsules of this wax, with the
socks having a ten-degree comfort zone. Another phase-change
approach is being tested using a compound known as
polyethylene glycol, or PEG for short. The PEG molecule is in
the form of a helix, like DNA. As the temperature changes the
molecule coils and uncoils, either giving off or absorbing heat.
Actually, this polymer does double duty. When PEG encounters
damp heat, i.e., sweat, it uncoils and traps the water and the heat.
Both effects are reversed when the wearer enters that air-
conditioned movie theater. Apparel incorporating PEG is
expected to be in your department stores within a year.
PEG also looks promising to the medical community. For some
reason, fabrics treated with this polymer aren''t good hosts for
microorganisms. This antibacterial property isn''t well understood
but the speculation is that microbes either can''t exist on the dry
fabric or perhaps the PEG alters the fabric in a way that the little
buggers just can''t hang on to the fibers. The FDA is currently
reviewing PEG-treated products such as bandages, scrubs for
doctors, bedding and blankets, footwear, dressings, etc.
If PEG-treated clothing doesn''t suit you, there is an alternative
killer fabric. There are compounds known as N-halamines,
whatever their formula, that are used in your local swimming
pools to stabilize the chlorine used to kill the germs. A company
in Seattle has found a way to attach the N-halamine molecules to
cotton. Now the cotton can offer chlorine atoms something to
hang on to and do their job of germ killing. Due out this year is a
line of chlorine-doped socks, uniforms, air filters, bandages etc.
Suppose the chlorine encounters so many little obnoxious critters
that it gets used up fighting them? You just recharge your
garment by washing it in the laundry with chlorine bleach. The
killer garment is loaded with chlorine, all set for another round of
bug fighting.
We''ve been talking about microbes so far. Are you as distressed
as I am about those millions of larger creatures we share our beds
with? Chances you''ve seen many pictures of these horrid looking
dust mites but yet have never heard of the fungus Aspergillis
repens. It never even occurred to me that the dust mites depend
on good old Aspergillis to break down those flakes of my skin to
form a suitable dish upon which the mites can dine. Now a
company in England has reportedly found that acrylic fibers can
be treated with a chemical that stops the fungus from
reproducing. As a result, Aspergillis fades away and the poor
dust mites starve to death. May they rest in peace!
While the above discoveries and applications seem quite
reasonable to me, the Discover article ends on a note that may be
stretching things just a bit too far. Apropos of last week''s
column, there is an Institute for Molecular Engineering, whose
president predicts that nano-manufacturing mills (like our plastic
spitting ink-jet printers) will spin out custom fabrics from the raw
materials such as carbon, nitrogen and oxygen. He envisions
sensors being incorporated into the fabric that will detect such
things as rips in the garment or the presence of specks of dirt.
These sensors will then dispatch nanorobots that will mend the
fabric or carry away the dirt to a collection area. Then this fellow
believes the tiny robots could circulate water throughout the
structure giving the equivalent of a rinse cycle!
Personally, I think the use of nanorobots for these frivolous duties
is truly beyond the pale. Better to concentrate on others'' visions
of tiny nanorobots scooting through our bodies cleaning up fatty
deposits in our blood vessels or devouring cancer cells and the
like. Actually, I don''t expect to live long enough to see
nanorobots employed in any of these capacities but I hope I''m
wrong about the medical possibilities. My own arteries could no
doubt use a good scouring!
Allen F. Bortrum
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