Condensation vs. addition polymerisation: which statement correctly distinguishes condensation systems from typical addition systems?

Difficulty: Easy

Correct Answer: Condensation monomers generally contain two functional groups each (difunctional).

Explanation:


Introduction / Context:
Polymerisation classifications help predict processing and properties. Condensation (step-growth) polymerisation typically links functional groups like –COOH, –OH, –NH2, or epoxide, sometimes liberating small molecules such as water or methanol. Addition (chain-growth) polymerisation adds unsaturated monomer units to a growing chain via active centers without losing small molecules.


Given Data / Assumptions:

  • Difunctional monomers (e.g., diacids, diols, diamines) are common in condensation systems.
  • Some step-growth reactions proceed without byproduct, but many release small molecules.
  • Addition systems typically involve unsaturated monomers (vinyls, dienes, olefins).


Concept / Approach:
The most reliable general distinction is monomer functionality: condensation polymers are formed when two or more functional groups on different monomers react to form linkages, often producing byproducts. Hence, “monomers generally contain two functional groups” is the correct statement. The other claims are overly absolute or incorrect.


Step-by-Step Solution:
Identify a generalised property that holds for condensation systems.Verify that difunctionality (or higher) is typical.Select the statement about two functional groups per monomer.


Verification / Alternative check:
Examples: PET (diacid + diol), nylon (diamine + diacid), phenolics (phenol + formaldehyde) all involve functional-group condensations.


Why Other Options Are Wrong:
Always unsaturated: false; condensation uses functional groups, not C=C necessarily.No co-product: many condensations release water/methanol, so this is false.Only one monomer: many systems involve two different monomers.Always lower molecular weight: depends on conversion and formulation.


Common Pitfalls:
Assuming byproduct formation is mandatory; some step-growth systems are “addition–condensation” without small-molecule loss.


Final Answer:
Condensation monomers generally contain two functional groups each (difunctional).

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