Skip to main content

Short note: Sulphur based polymers

Short answer

Sulphur-based inorganic polymers include plastic sulphur (quenched from melt, rubbery chains), polythiazyl (SN)x (metallic conductor), and polysulphide rubber (Thiokol) made from ClCH2CH2Cl and Na2S4. Thiokol resists oils and solvents, used for sealants and hoses.

Write a short note on sulphur based polymers.

Sulphur forms inorganic polymers because S atoms can catenate (S–S bonds) and link with N.

  1. Plastic sulphur: Ordinary rhombic sulphur has S₈ rings. When sulphur is heated above about 160 °C, the rings open and join into long chains (S)ₙ, and the liquid becomes very viscous. If this hot liquid (heated to near its boiling point) is poured into cold water, the chains are frozen as a brown, rubber-like, elastic solid called plastic sulphur. It slowly reverts to the S₈ form.
  2. Polythiazyl (SN)ₓ: a chain polymer of alternating S and N, made by polymerising S₂N₂ (from S₄N₄ over hot silver wool); a metal-like conductor and a superconductor at about 0.3 K.
  3. Polysulphide rubber (Thiokol): n ClCH₂CH₂Cl + n Na₂S₄ → [–CH₂CH₂–S₄–]ₙ + 2n NaCl; oil and solvent resistant, used for sealants, gaskets and fuel hoses.
  4. Sulphur network (chalcogenide) glasses such as As₂S₃ for infrared optics.

Sulphur cross-links also vulcanise rubber.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Engineering Chemistry chapter 4 questions →