The biggest fashion breakthrough of the '90s is less apt to spring from a runway in Paris than from a laboratory in Wilmington, Del. Without fanfare, Du Pont, among other mills, has been concocting synthetic "performance" fibers that dramatically improve on the natural—and will no longer carry the déclassé stigma of polyester.

CALVIN KLEIN signaled designer acceptance of these new test-tube textiles with a $1,250 quilted dress parka made from the most sophisticated so far: microfiber, which is softer and more luxurious than silk, DONNA KARAN is also known to be experimenting with this revolutionary new chemistry, first stretched by the demands for superior athletic wear.

A precursor was Lycra (1960), now finally elevated from bathing suits to evening gowns. "It gives a wonderful sleek look," says Randolph Duke, who features it in jumpsuits and turtle-necks. Du Pont's four-year-old Supplex, a cottony nylon billed as "stronger than steel," is also suddenly chic. "I used to be opposed to synthetics," confesses designer DIANNE BEAUDRY, whose new collection includes Supplex chemises and bodysuits. "But the great selling point of Supplex is that it won't fall apart."

By 1999, labs expect new fibers that, in one garment, will keep you warm in winter, cool in summer. New dyes could enable people to change the color of a jacket at will—thus, you might pack one for a trip instead of two or three. Some novelty kids' clothes already have coatings that turn different shades in water or at different air temperatures.

"Once people experience the new synthetics, they won't want to wear anything else," promises forecaster David Wolfe. He may not be far off. At a recent European trade fair, a sales rep was overheard promoting a new natural weave as "cotton with a microfiber feel."