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:
“One year, I’d completely lost my bearings trying to follow potty training instruction from a psychiatric expert. I was stuck on step on, which stated without an atom of irony: “Before you begin, remove all stubbornness from the child.” . . . I knew it only could have been written by someone whose suit coat was still spotless at the end of the day, not someone who had any hands-on experience with an actual two-year-old.”
—Mary Kay Blakely (20th century)
“It is in the comprehension of the physically disabled, or disordered ... that we are behind our age.... sympathy as a fine art is backward in the growth of progress ...”
—Elizabeth Stuart Phelps (1844–1911)
“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)