Ion-exchange resin matrices: commercial cation/anion exchange resins are typically based on which polymer backbone?

Introduction / Context:
Ion-exchange resins are widely used in water treatment, deionisation, and catalysis. The polymer backbone must be chemically robust and allow introduction of ionic functional groups. Recognising the standard matrix helps in predicting resin stability and performance.

Given Data / Assumptions:

• Most commercial resins use a styrene–divinylbenzene (DVB) copolymer matrix.
• Cation exchangers are typically sulphonated; anion exchangers are amine-functionalised.
• Backbone must withstand aqueous environments, pH cycling, and thermal loads.

Concept / Approach:
Polystyrene crosslinked with DVB provides a rigid, porous network that can be functionalised. Alternative backbones exist (e.g., acrylic resins) but classical, general-purpose resins are styrenic. Bakelite (phenol-formaldehyde) is thermoset and brittle; PTFE (Teflon) is chemically inert but difficult to functionalise for ion exchange and lacks the typical porous network needed. Lucite (PMMA) is transparent acrylic, not the mainstream ion-exchange matrix.

Step-by-Step Solution:
Identify the standard commercial choice: polystyrene–DVB.Note functionalisation methods: sulphonation (cation), amination/quaternisation (anion).Exclude alternatives that are not typical ion-exchange matrices.

Verification / Alternative check:
Manufacturer datasheets and handbooks repeatedly specify styrene–DVB for strong-acid/strong-base resins.

Why Other Options Are Wrong:
PMMA, bakelite, PTFE: not the mainstream, general-purpose ion-exchange resin backbones.

Common Pitfalls:
Confusing the functional group (e.g., sulphonated) with the backbone polymer; the backbone is styrene–DVB.

Final Answer:
Polystyrene (crosslinked with divinylbenzene)