Controlled Radical Polymerisation and Block Architecture · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Growing chains that stay alive

Science · Chemistry · ages 23-24
Name ______________________   Date ____________

  1. You plan a two stage block copolymer. When do you add the second monomer?

    • Before the first block starts
    • Together with the first monomer
    • After the first block nears full conversion

  2. How does a dormant active equilibrium suppress termination without stopping growth?

    • It holds most chains dormant so few ever meet
    • It freezes all motion in the flask
    • It removes the initiator entirely

  3. In a controlled run, most chains rest dormant and only a few grow at once.

    Circle one:   True   False

  4. A final trace shows a broad peak with a shoulder after the second feed. What does it show?

    • All chains extended cleanly
    • Some chains died before extending into the second block
    • The detector ran out of solvent

  5. You double the monomer per initiator at full conversion. What happens to the expected average length?

    • It halves
    • It doubles
    • It stays the same

  6. Adding the second monomer very early still gives a clean block join.

    Circle one:   True   False

  7. You set 200 monomers per initiator but stop at half conversion. What average length do you expect? Type the number.

    Answer: ______________

  8. A block run used the right ratios and order, yet the final distribution is broad. What does the breadth mean?

    • The blocks joined in perfect order
    • The dormant state worked too well
    • Control was lost partway through the run
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Growing chains that stay alive W1-mt_nQKYR0yEEs-s1

  1. After the first block nears full conversion · Living ends must finish the first block before extending it.
  2. It holds most chains dormant so few ever meet · Sleeping chains cannot meet, while each wakes in turn to grow.
  3. True · That balance keeps chains alive and growing together.
  4. Some chains died before extending into the second block · Shoulders and breadth mark chains that died early.
  5. It doubles · Length tracks the ratio, so doubling the ratio doubles the length.
  6. False · An early feed makes a tapered middle, not a clean join.
  7. 100 · Half of the ratio grew: half of 200 is 100.
  8. Control was lost partway through the run · Right settings with a broad end mean termination or transfer broke in.
Worksheet · LightMySky