Hydroxy terminated silicone oils are very common - they are called silanols.

Thanks for your comment, I need diols not only one OH. Could you suggest silandiols?

From what I understand of silicon chemistry, you would have to look extra hard to find a monofunctional silanol. Look at what Gelest has (www.gelest.com)

What you planned to make from this diols? I think much different diols described. Do you need industrial product?

I want to make polyesters from these diols (silicone, sulfur, or phosphorous-based diols) and an acid dichloride

I think some of siloxane-contain diol used in polyurethanes. In the end, I see POSS diol http://us.chemicalbook.com/ChemicalProductProperty_US_CB2504456.aspx.

I think many of proper diol exist in world.

Select your choice here:=>

http://www.siltechpersonalcare.com/pdfs/products/Reactive_Silicones.pdf

I buy from them. Many silicone derivatives.

Your other choice would be BYK Chemie.

But it will be a problem to obtain the samples.

They will ask how many kilos per year you intent to consume?