You may be right, and I may have been fooled by the white texture diaphragms of the SA3000 and SA5000, looking very much like the biocellulose membranes of the CD3000 and CD2000. "Nanocomposite" is a combined material (fibre/filler) on a microscopic level, producing a strong and stiff material. Since companies want to keep its manufaturing processes secret, Sony never told us what materials the SA3000, SA5000 and Qualia membranes were made of.
The CD1700 and CD2000 used Vectran as fibre base to the biocellulose, and Vectran is actually a liquid crystal polymer, LCP, which is the material used for the MDR-Z1000 diaphragm. The Z1000 membrane is golden transparent with no visible fibre structure. This may be due to the nanocomposite manufacturing process, melting fibre and filler together.
Enclose a few pics of the different drivers.
Sony Qualia:
Sony SA5000:
Sony CD3000:
Sony MDR-Z1000: