A growing movement against plastic straws is playing out in Chicago, with restaurants and museums banning the items, and a South Side straw factory urgently seeking an environmentally friendly alternative for slurping down a soda or chocolate shake. The single-use plastic straw — colorful, functional and handed out in bunches — has suddenly shifted from consumer staple to scourge, projected by some critics to foul ecosystems for an eon. Scores of Chicago-area restaurants have already shunned plastic straws, along with colleges and a number of cultural venues, such as the Shedd Aquarium.