| |
 |
|
|
Science Forum Index » Materials Forum » Polymers-Carbon Nanotube Nanocomposites
Page 1 of 1
|
| Author |
Message |
| Ebi |
 Posted: Wed Sep 10, 2003 10:38 am |
|
|
|
Guest
|
Dear Guys;
In fact I work on PMMA-CNT nanocomposite. Actually I faced with a
problem! If you have same experience would you please help me!?
As you know DMF is a great solvent for CNTs and PMMA, but I can't make
thin film by spin coating! Do you have any idea?
I appreciate
Ebi |
|
|
| Back to top |
|
| Uncle Al |
| Posted: Wed Sep 10, 2003 11:40 am |
|
|
|
Guest
|
Ebi wrote:
Quote:
Dear Guys;
In fact I work on PMMA-CNT nanocomposite. Actually I faced with a
problem! If you have same experience would you please help me!?
As you know DMF is a great solvent for CNTs and PMMA, but I can't make
thin film by spin coating! Do you have any idea?
I appreciate
If the nanotubes tangle they will act as crosslinking. You will get
fisheyes and other lumps. Try ultrasonicating just before spin
coating. DMF is a proven weak testicular carcinogen. Avoid skin
contact and don't breath the vapor. Aircaft technicians who bathed in
polyurethane connector depotting goop eventually sang soprano.
Another angle is a surfactant to tie together the phases across their
interface. We know that high curvature graphene sheets strongly bind
imidazolium ionic liquids (big tech press coverage). Methylimdiazole
is quaternized with a short aliphatic chain. There is no reason that
a modestly longer chain can't be functionalized at its other end to
make it strongly compatible with PMMA (or use a short
imidazolium-functionalized oligomer of PMMA). You'd only need a teeny
tiny bit to coat the nanotubes's surface before adding the PMMA
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net! |
|
|
| Back to top |
|
| Ebi |
| Posted: Thu Sep 11, 2003 2:56 am |
|
|
|
Guest
|
Hi Uncle! Thanks a lot for your answer! As you know, sonication can
make so many damages and also can cut CNTs and this phenomenon in my
case can decrease the thermal stability of produced nanocomposites.
Anyway I use this method as usual.
But about the second paraghraph. In fact I could'nt catch the point!
Sorry! Do you mean I have to modify the surface of CNTs? What kind of
modification?! Now. Plasma polymerisation is ok?
Can I ask another question?! Have you ever characterised CNTs by STM?!
I tried several times but I was not sucessful!
Thanks again
Ebi |
|
|
| Back to top |
|
| Uncle Al |
| Posted: Thu Sep 11, 2003 10:03 am |
|
|
|
Guest
|
Ebi wrote:
Quote:
Hi Uncle! Thanks a lot for your answer! As you know, sonication can
make so many damages and also can cut CNTs and this phenomenon in my
case can decrease the thermal stability of produced nanocomposites.
Anyway I use this method as usual.
But about the second paraghraph. In fact I could'nt catch the point!
Sorry! Do you mean I have to modify the surface of CNTs? What kind of
modification?! Now. Plasma polymerisation is ok?
Can I ask another question?! Have you ever characterised CNTs by STM?!
I tried several times but I was not sucessful!
A flat graphene sheet is graphite - a plane of conjugated pi electron
density. It readily interacts with strong Lewis acids. When you add
curvature you enhance its nucleophilicity, promoting interaction with
weaker Lewis acids. Nanotubes are strongly curved.
You need compatibilization. You must enhance bonding betwen the
matrix and its filler so that you get a strongly couple composite and
the filler does not want to aggregate rather than disperse. Graphene
is notorious for being inert, slippery, and self-aggregating. You
need a surface modifier.
Unlike mineral fillers and functional silanes or titanates, there is
no graphene covalent chemistry (except maybe at their ends) without
destroying the graphene network. There is, however, rich
charge-transfer chemistry under very mild conditions,
Google
nanotubes imidazolium 132 hits
Imidazolium ionic solvents *very* strongly interact with nanotube
surfaces by demonstration. The nanotubes remain chemically
unaltered. That is one hook, and the really difficult one. PMMA will
absolutely hate ionics. N-Methyl imidazole is typically quaternized
with a butyl group on its sp2-nitrogen. Aldrich hasa lovely circular
on ionic solvents. Have the quaternizing group, whatever it is, be
functionalized at its distal end or use a functionalized PMMA
oligomer. Now you have a bifunctional detergent to compatiblize the
otherwise high energy interface beteen nanotube filler and PMMA
matrix. In electronics they call it impedence mathching. In
hydraulics you would be inserting a taper to connect a big diameter
pipe to a small diameter pipe to prevent a momentum discontinuity
(shock).
The amount of compatiblizer needed is vanishingly small. All you need
do is bond a sub-monolayer to the nanotubes, then disperse them in the
PMMA. The tactics may run hot and cold, but the strategy is sound.
If it doesn't work given a few good shots, you try somebody else's
clever idea. What you have now obviously doesn't work.
An engineer faced with a system that does not work - things - seeks
optimization. A scientist faced with a system that does not work -
stuff - seeks invention. Any manager knows that optimization is
PERT-chart mathematics and a sure thing, but invention is an expensive
crapshoot. B-school says, "Never assume unquantified risk!!!" What
they don't tell you in B-school is that if there is no maximum,
optimization cannot find it.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net! |
|
|
| Back to top |
|
| |
|
Page 1 of 1
All times are GMT - 5 Hours
The time now is Mon Oct 13, 2008 7:48 pm
|
|