wire shielding

i want buy some wire to make interconnect cable.
do anyone know what are difference between silk ;teflon and PVC cover of wire? thanks
My understanding is that any natural material like silk will eventually let enough oxygen through to oxidize the wires and that could be a bad thing. I believe teflon is a good material in that it protects the wire without introducing capacitance or impedence issues.
The thing about silk, is it will hold a static charge, especially if you like stroking your ICs on your bearskin rug :~))
Rather than pretending to know more than I do, I recommend that you look at Enjoy the Music website and Audioholics for good discussions of wire. That includes the shielding, inductance, capacitance and resistance. I likewise will shortly buy wire and supplies to make interconnects. I am still deciding if I want a coax style with a center conductor, or a twisted wire type. The short answer is that Teflon is second only to air as a dialectric and this reduces capacitance. Apparently, many commercial interconnects use PVC, but Teflon is superior as a dialectric. Whether this is significant to the sound is matter of debate. TNT-Audio also has good discussions about the electrical properties of materials in the production of audio wires, including a few good DIY projects. Good luck!