It's called "electrochromic glass". Do a google search for more info. This glass tints when voltage is applied. It never becomes completely opqaque.
The variety you're looking for is called "Liquid Crystal Glazing" or PDLC. It turns completely transparent when voltage is applied.
http://www.glassonweb.com/glassmanual/index.php
http://www.howstuffworks.com/smart-window2.htm
This company, Priva-Lite, will send you their demonstration kit to keep for 245 Euros... ~ $238... a bit pricey, eh?
http://www.sggprivalite.com/en/sommaire.html
http://www.sage-ec.com/
These aren't commercial products... so that $250 demonstration kit is all you'll find. I suggest you switch projects. If this is a research paper, tell me so I can delete this post and you can
DO YOUR OWN RESEARCH.