Step Growth Polymerisation and Condensation Polymerization
"Step growth polymerisation" and condensation polymerization are two different concepts, not always identical. In fact polyurethane polymerizes with addition polymerization (because its polymerization produces no small molecules), but its reaction mechanism corresponds to a step-growth polymerization.
The distinction between "addition polymerization" and "condensation polymerization" was introduced by Wallace Hume Carothers in 1929, and refers to the type of products, respectively:
- a polymer only (addition)
- a polymer and a molecule with a low molecular weight (condensation)
The distinction between "step-growth polymerization" and "chain-growth polymerization" was introduced by Paul Flory in 1953, and refers to the reaction mechanisms, respectively:
- by functional groups (step-growth polymerization)
- by free-radical or ion (chain-growth polymerization)
Read more about this topic: Step-growth Polymerization
Famous quotes containing the words step, growth and/or condensation:
“I grieve that grief can teach me nothing, nor carry me one step into real nature.”
—Ralph Waldo Emerson (1803–1882)
“But parents can be understanding and accept the more difficult stages as necessary times of growth for the child. Parents can appreciate the fact that these phases are not easy for the child to live through either; rapid growth times are hard on a child. Perhaps it’s a small comfort to know that the harder-to-live-with stages do alternate with the calmer times,so parents can count on getting periodic breaks.”
—Saf Lerman (20th century)
“Entification begins at arm’s length; the points of condensation in the primordial conceptual scheme are things glimpsed, not glimpses.”
—Willard Van Orman Quine (b. 1908)