Bill, there are a lot of different synthetics used for insulation. Ray Jardine is a big proponent of synthetic for his quilts-
http://www.rayjardine.com/ray-way/Quilt-Kit/index.htm

There are continuous filament and chopped fiber batts that will substitute for down. Ray uses a continuous filament batt. They can be used in jackets as well. Wiggy uses something similar. Primaloft is one brand. Some jackets use Thinsulate, which is also used in boots.
http://www.primaloft.com/en/performance/products.html

Google down v. synthetic and there articles, videos, blogs, posts, the whole gamut on the Internet.