Last week, Emma Watson sported a 'sustainable' Calvin Klein outfit to Met Gala 2016: 'Manus x Machina: Fashion In An Age Of Technology'. All the headlines read "WATSON'S DRESS MADE OF PLASTIC BOTTLES!" but that was all the info we were getting. 
Now, in the last ten minutes, the actress has posted just what makes the outfit 'sustainable', and it's very impressive - particularly the bit about you being able to wear it 30 times. Not that a celebrity would ever wear the same red carpet offering 30 times, but it's nice to know they could.  

As for why you should recycle, that's addressed at the bottom of the below picture - namely "Just 1 plastic bottle takes 450 years to biodegrade"