Molecular information on the dissolution of polydisperse polymers: Mixtures of long and short poly(ethylene oxide).
A systematic study of the dissolution of dry, polydisperse poly(ethylene oxide) (PEO) samples, obtained from mixtures of low-molecular-weight and high-molecular-weight PEO, was made. During the dissolution process, the individual release of the low- and high-molecular-weight fractions was monitored. The high-molecular-weight/low-molecular-weight ratio controls the release rate, and the fraction of high-molecular-weight polymers dominates the effect on the overall release rate in mixed PEO tablets. Both fractions are released at the same rate during the main part of the dissolution process; however, during the initial dissolution period a fractionation occurs. The release rate is not a unique function of the average molecular weight of the polymer, but also depends on the polydispersity. By contrast, the average dimension of a polymer coil, as given by the intrinsic viscosity, gives a good prediction of the release rate irrespective of the polydispersity or details of the molecular weight distribution.
Körner
Anna
A
Department of Physical Chemistry 1, Lund University, Box 124, SE-221 00, Lund, Sweden.
Larsson
Anette
A
Piculell
Lennart
L
Wittgren
Bengt
B
D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D012995:Solubility; D012996:Solutions / Q000737:chemistry
D011108:Polymers; D012996:Solutions; D011092:Polyethylene Glycols