No, they are not.
If the bottles were to be autoclaved, it could cause some discoloration because of the plastic coating. In addition, autoclaving by heat will melt the plastic coating, and autoclaving by gas may discolor and harden the plastic. In either event, it is not recommended. They are designed to be used at ambient temperatures.
To sterilize, we recommend using the non-coated bottles with a safety mesh which can be purchased from your local laboratory supply distributor.
The bottle caps that are provided with these bottles generally can withstand 140°C.