A sample taken during a chain
growth polymerization will not have
A.
O polymer
B.
O active growing chain
C.
initiator
D.
O Starting monomers
Answers
Explanation:
In 1953, Paul Flory first classified polymerization as “step-growth polymerization” and “chain-growth polymerization”.[2] IUPAC recommend to further simplified “chain-growth polymerization” to “chain polymerization”. It is a kind polymerization where an active center (free radical or ion) is formed, and a plurality of monomers can be polymerized together in a short period of time to form a macromolecule having a large molecular weight. In addition to the regenerated active sites of each monomer unit, polymer growth will only occur at one (or possibly more) endpoint.[3]
Many common polymers can be obtained by chain polymerization such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate.[4]
Typically, chain-growth polymerization can be understood with the chemical equation:
{\displaystyle P_{x}*+M\rightarrow P_{x+1}+L(x=1,2,3...)}{\displaystyle P_{x}*+M\rightarrow P_{x+1}+L(x=1,2,3...)}
In this equation, P is the polymer while x represents degree of polymerization, * means active center of chain-growth polymerization, M is the monomer which will react with active center, L is a low-molar-mass by-product obtained during chain propagation. Usually, for chain-growth polymerization, there is no by-product formed. However, there are still some exceptions. For example, amino acid N-carboxy anhydrides polymerizing to oxazolidine-2,5-diones.