Steve Morton wrote:
***
 I need a moldable material with which I can form disks that are 50 to
10= 0 mm in diameter and 0.5 to 1.0 mm thick (larger disks are the
thicker). I need to be able to impart microstructures into both
sides with a minimum feature size of 0.7 to 1.0 micrometers
square. I need a low coefficient of linear expansion (this is the
hard part) of about 5 x 10E-6 (10 times lower than acrylic). It
needs to be capable of taking an optically smooth finish and
 strong enough to rotate at 3,600 to 7,200 rpm.
***
We have a Swedish research project on polymeric microstructures where we
collaborate with Toolex Alpha, a manufaturer of machines for Compact Disc
fabrication, so I understand your problem. Since most polymers have a larger
expansion coefficient than what you ask for the solution to your problem may be
to mix > 40% glass beads or glass fibers in the plastic. Polystyrene or
polycarbonate can be used in this way. If this is acceptable for yor
application we may be able to help you. Please don=B4t hesitate to contact me
if you have any further questions.

Hakan Elderstig
Swedish Industrial Microelectronics Center
email: hawk@imc.kth.se