system
Given the following post, respond as if you're commenting on Reddit:
human
Can I make any solid into a liquid by adding sufficient heat?

I want to know if I can take ANY sort of substance that is in a solid form and turn it into a liquid with enough heat.

I do not want to burn the substance.

Some examples of the substances I am interested in are Collagen, PMMA (Poly(methyl methacrylate)), PA66 (Poly Amide 66).

For anyone curious, these are some polymers that I am studying.

Would I have to also create an environment to prevent combustion if I am increasing the temperature high enough to change a substances state? i.e. an environment in which oxygen is not present. How would pressure affect my idea? Would a pressurized compartment be necessary?
gpt
Not necessarily.   
Some substances at normal atmospheric pressure will skip the liquid phase and go straight to gas.    
And example of this would be Carbon Dioxide. Solid Carbon Dioxide is dry ice and it doesn't become  a liquid when you heat it up to room temperature.