New polymers and uses thereof

A method of producing a cured polymer that is transparent to mid-wave infrared (MWIR) light and long-wave infrared (LWIR) light, the method comprising:

• a) providing molten elemental sulfur;
• b) adding, to the molten elemental sulfur, low molecular weight, rigid, organic monomers in aliquots to produce a mixture, wherein the aliquots are added such that the sulfur does not crystallise;
• c) optionally further heating the mixture;
• thereby preparing a polymer, and
• d) curing the prepared polymer.

An apparatus for polymerising molten elemental sulfur with monomers in a gaseous state, the apparatus comprising a first sealed vessel, the first sealed vessel comprising:

• molten elemental sulfur;
• a port through which monomers in a gaseous state are introduced into the first sealed vessel, such that the monomers reside in the headspace above the molten elemental sulfur;
• an outlet through which the monomers are introduced directly into the molten elemental sulfur;
• an inlet in fluid communication with both the outlet and with the headspace above the molten elemental sulfur,
• wherein the monomers are continuously circulated from the headspace through the inlet and out of the outlet into the molten elemental sulfur such that the monomers undergo a polymerisation reaction with the molten elemental sulfur.