Polyimide & Graphene Oxide (GO) : A Start to a Summer of Composites

This summer my research focuses on making polyimide/graphene nanocomposites. Those sure are some words, right? I’d rather just break it down into four introductory questions:

  1. Who am I?
  2. What are polyimides?
  3. What is graphene oxide (GO)?
  4. Why on earth are we trying to make composite materials from these particular materials?

So lets start off with the easy question (well, it might be hard, it depends how philosophical we’re getting here.)

Who am I?

I’m Natalie — hello! This is my last summer here at the College which means senior year is coming (ah!). I am a Chemistry major from Fredericksburg, VA and I’ve been involved in Dr. Kranbuehl’s research lab since freshman year. This is starting to sound a little it like a resume so how about some slightly more interesting personal facts? I fence foil here with the William and Mary Fencing team, I enjoy rockclimbing casually (and sometimes falling), embroidery and hand sewing.

Now you know! And on to the more difficult questions:

What are polyimides?

Polyimides are a class of high performance polymers. They are thermoset polymers which means that once they are completely set, made, done, they’re done — there is no going back and there is no melting. They have incredible thermal stability and mechanical properties. This just means they’re great for high temperature high stress situations, think industrial machinery and electronics. There are even polyimide tapes in our friend Mars Rover Curiosity. Also, they’re a characteristic almost beautiful yellowy-orange color though transparent which I think is a cool bonus.

What is graphene oxide (GO)?

You might not have heard of graphene oxide but you’ve probably heard of graphene. It was the subject of the Nobel Prize in Physics in 2010. Graphene is a single atom thick layer sheet of carbon atoms arranged in a honeycomb structure and is incredibly strong. Graphene Oxide is this basic structure but with the addition of oxygen via hydroxy groups, carbonyl groups and epoxy bridges. Pristene graphene, aside from being a fun rhyme, is perfectly flat. This is not the case with Graphene Oxide and it is not as strong as pristine graphene but it is more hydrophilic than graphene. Pristine graphene is extremely hydrophobic which makes it, well, hard to put into stuff. Therefore, GO is the better choice as we get to keep some of the amazing structural properties and have the hydrophilic groups we need to, well, basically, make the stuff go together.

Why on earth are we trying to make composite materials from these particular materials?

Polyimides are pretty great on their own, don’t get me wrong, but what if we could make them better? Incorporation of GO into the polymer matrix could potentially improve the mechanical properties of the material as well as potentially creating a polyimide that already has all of its own great properties but is a fantastic gas barrier.

The struggle will be in all the actual bench work because a) things look easier on paper b) the devil’s in the details. Overall, we’re striving for homogenous dispersions and reproducible samples without macro structural defects from the production process.

Comments

  1. Natalie, can’t agree more with ‘the devil;s in the details’!
    One question: How incredible the mechanical properties of polyimide are, compared to GO? (I could google it but maybe you have a metaphor better than the numbers themselves.) =]

  2. nvhudsmith says:

    Hi Jing!
    I’ve found some pretty handy numbers for comparison. Pristene Graphene is famous for the Young’s Modulus of 1000 GPa. I looked up the Young’s Modulus for Graphene Oxide (Suk et al. ASCNano) which was found to be 207.6 GPa. This is expected, of course, because of the defects and crinkling due to the additional oxygen functional groups.
    Polyimide mechanical properties really depend on the polyimide — there are quite a few kinds out there but I found a site that lists their film for purchase and cited the polyimide Young’s Modulus at anywhere from 8-15 GPa. So, graphene oxide and graphene are of magnitudes stronger. I guess I don’t really have a metaphor for this handy but I’ll try to think of one. On an intuitive level, though, this concept always reminds me of the practice of adding rebar to reinforced concrete, just waaaay tinier. 🙂