As per the subject. I have looked online and in a number of stores (M&S, Mothercare, John Lewis, JojoMaman, etc.) but couldn’t find any – they all tend to be between 80 and 100% cotton.
The reason I ask is because our child, now almost 3, sweats a lot from her feet, even when it’s not warm and she’s not running around all the time, and her socks are often wet from the sweat. Cotton may have lots of nice properties but is a terrible fabric for sweating: it does not wick sweat away like merino, silk or most synthetic fabrics, but gets drenched and stays wet. Her shoes are ordinary Clarks, made of leather, without any kind of fleece or thermal lining.
Merino and silk are expensive fabrics, so it makes sense they might not even make kids’ socks in these fabrics, but polyester isn’t.