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An effort to control mold growth
Pittsburgh Post-Gazette


January 24, 2007

It ruins more than old bread.

It can blemish floors, walls and ceilings and destroy entire homes. Worse, it can affect human health.

Long it's been told
of the boldness of mold,
which can damage a home
so it can't be sold.

As it unfolds,
the famed fungus of old
can cost the poor owner
a carload of gold.

Bad but true poetry aside, the Insurance Information Institute said insurance payments for mold damage amounts to a whopping $2 billion a year.

Alan Russell, University of Pittsburgh professor of chemical and petroleum engineering, has led a team in developing coatings that prevent mold growth. The technology could be used in mold-repellent mixtures and coatings to protect everything but bread.

For now, Russell said, he's awaiting someone in the construction industry to take notice of the published research and use it. He said the technology would have many applications in construction.

His team developed a hairy polymer surface that causes mold's filaments, known as mycelia, to explode before they produce spores.

The method reduces to a basic biophysical process: The hairy polymer carries a positive charge. After a few intermediate processes, the negatively charged mold couples like a magnet with the positively charged polymer. That's when the polymer's spray of ions pops open the membrane of the mold's mycelia, making it impossible to produce spores.

To date, Russell and crew have produced two types of mold-popping polymers. One repels water and the other is water-soluble. Both restrict spore production in a battle of filaments: polymer hairs vs. mycelia.

Russell's crew tested its polymers on wood soaked in potato broth, which produces a circus of molds. Tests showed success. Wood covered with the polymer developed no moldy spots.

As that happens, Russell said his team continues figuring out whether the fungi can become "more clever," and what will happen if the mold-repelling surfaces his team created becomes dirty.

That's what piqued Russell's interest in producing growth-killing polymers that mimic the "lotus effect." Despite living in dirty ponds, the lotus leaf never gets dirty. As it turns out, its hydrophobic (or water-repellent) surface prevents water from ever touching the leaf. As water rolls off, it dissolves dust and dirt, leaving the leaf forever clean.

"It's perfectly repellent," Russell said. "We hope to design a surface like the lotus leaf that also will kill the fungus."

While the lotus effect inhibits natural substances from sticking to surfaces, there's uncertainty whether it also can repel industrial chemicals, diesel fuel and oil that could ruin the mold-inhibiting effect.

Which prompts us to end this story before it gets moldy. Russell's team of researchers proved the basic principle and met MSI's challenge by developing mold-inhibiting surfaces.

"Now someone needs to come along and give it a try," he said. "It has broad utility."

A journal article on the research was published late last year, with anticipation of subsequent articles to update the research.

For now, his team is figuring out whether it would be best to mix the polymer in paint or create a coating to apply over painted surfaces. The team also is trying to figure out how long the mold repellent will remain on surfaces and whether surface dirt will reduce its repellent qualities.

"This won't happen overnight," Russell said. "But we now understand the biology, chemistry and the materials and now can define applications."

In new technology for repelling molds, only time will tell what next unfolds.



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