The GC3 has a Fellows Program meant to address this exact problem, but it takes place during the summer and the application period won't be until early next year, which I assume is too late for your purposes. If not, you can check out last year's criteria here: GC3 Fellows Program 2015 — Green Chemistry and Commerce and keep an eye out for updates from the GC3!
The green chemistry field is pretty small, so being a Ph.D. student interested in green chem already gives you a unique advantage. In my experience, there are many companies who would be willing to take on an intern for a couple of months, but they don't necessarily advertise their openings. Some companies who do GC work that you might be surprised by include:
I'm not going to list them all here, but take a look at the Innovation Map for more examples of companies and non-profits involved in GC. Glance at their job postings and see if there are any internships listed at companies you're interested in, then let me know if there are some companies that you'd like contacts at!
You may try Creative Biolabs. These days we have new members joined in regularly, but I'm not so sure about it since I'm not in the the department of HR. You may also follow our facebook, cause the HR will put new recruits on it.
If you are going to be at the Boston ACS, take a walk around the exhibition floor with a stack of business cards in your pocket and have conversations with various folks you run into there. The ACS Green Chemistry Institute will certainly be there, and there may be representation from Green Centre Canada, Chem21 in the UK, the Warner Babcock Institute/Beyond Benign, as well as more mainstream companies who may be able to connect you to relevant people in their sustainability divisions, which are increasingly working on green chemistry and materials challenges.
Additionally, your university likely has a careers centre with a searchable database; these are sometimes targeted more at undergraduate students but if the filters are well designed these may be fruitful.
Finally, let everyone you know know what you are looking for. If you add this information to your Linkedin profile, for example, you may be surprised how many connections you get. Some will be more relevant than others, but follow up respectfully and appropriately and this could even point you beyond an internship and into a career.
Hard-working green-minded PhD student based in NYC looking for a 2 month to 4 month industry internship to garner a better understanding of how green chemistry in industry works. While my background is in organic materials, I have organic chemistry and engineering experience.
Looking for connection to potential industrial advisors for an applicable internship. Very open to all ideas.