MChem Master of Chemistry Polymer Chemistry 2

Question 1

Which of the following is an example of a condensation (step-growth) polymer?

Accepted Answer

Nylon-6,6

Answer

Nylon-6,6 is formed by condensation of hexamethylenediamine and adipic acid with elimination of water, a classic step-growth mechanism.

Question 2

What does the Carothers equation predict in step-growth polymerization?

Accepted Answer

The number-average degree of polymerization as a function of monomer conversion

Answer

The Carothers equation, DP̄n = 1/(1-p), relates the number-average degree of polymerization to the fractional monomer conversion p, showing high conversion is needed for high molecular weight.

Question 3

In atom transfer radical polymerization (ATRP), what component serves as the persistent radical?

Accepted Answer

The Cu(II) complex (oxidized metal halide)

Answer

In ATRP, the Cu(II)/L complex is the persistent (stable) radical that caps the propagating chain, maintaining low active radical concentration via the persistent radical effect.

Question 4

Which analytical method directly measures the absolute molecular weight of a polymer without calibration standards?

Accepted Answer

Multi-angle light scattering (MALS)

Answer

Multi-angle light scattering (MALS) measures the absolute weight-average molecular weight directly from the angular dependence of scattered light intensity without requiring calibration standards.

Question 5

What structural feature distinguishes an isotactic polymer from an atactic polymer?

Accepted Answer

Isotactic polymers have all pendant groups on the same side of the backbone

Answer

In an isotactic polymer, all repeat units have the same relative configuration (all pendant groups on the same side of the extended backbone), allowing efficient chain packing and crystallization.

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Polymer Chemistry 2