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Cross linked polymer; inorganic polymer; chalcogenide

Short answer

Cross-linked polymers have covalent bridges between chains forming a 3D network, e.g., Bakelite, infusible. Inorganic polymer traits: high thermal stability, non-flamability, oxidation resistance, flexibility, good insulation. Calcogenide glass engineering uses: IR lenses, phase-change memory, photocopier drums.

What do you mean by cross linked polymer? What are the general characteristics of inorganic polymer? What are the engineering application of chalcogenide polymer?

Cross-linked polymer

A cross-linked polymer has its linear chains joined together by covalent bonds (cross-links) to form a three-dimensional network. It is hard, rigid, insoluble, infusible and does not melt on heating. Examples: Bakelite, vulcanised rubber, epoxy resin, melamine–formaldehyde.

General characteristics of inorganic polymers

An inorganic polymer is a polymer whose backbone is made of atoms other than carbon (e.g. Si–O, P–N, S–N, B–N). Examples: silicones, polyphosphazenes, polythiazyl, plastic sulphur.

General characteristics:

  • High thermal stability (strong backbone bonds such as Si–O, 452 kJ/mol) and non-flammability.
  • High chemical and oxidation resistance, and weather resistance.
  • Flexibility at low temperature (low glass transition temperature) because of easy rotation about Si–O or P–N bonds; many are elastomers.
  • Good electrical insulation (some, like (SN)ₓ, conduct).
  • Usually higher cost, and some are sensitive to hydrolysis.

Engineering applications of chalcogenide glasses

  • Infrared lenses, windows and fibres for thermal imaging, night vision and sensing.
  • Phase-change memory and rewritable optical discs (Ge–Sb–Te).
  • Photoreceptors in photocopiers (amorphous Se, As₂Se₃).
  • Switching devices, solar cells and chemical sensors.

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