A friend working with polymers told me recently that their patents tend to be vague as well, in order to block as many variations and modifications to given formula as possible, while not revealing the exact chemical process used to obtain the polymer (e.g. saying that the temperature used is between XX and YY, instead of providing the exact value).

I'm not as familiar with polymer chemistry but I worked as a lab chemist in medicinal research and there there's really not much room for vagueness.