Self-diffusion and molecular mobility in PVA-based dissolution-controlled systems for drug delivery.
Nuclear magnetic resonance (NMR) microscopy has been used to monitor the hydration of poly(vinyl alcohol) (PVA) samples of varying molecular weight. One-dimensional profiles weighted to predominantly show the variation of water concentration were acquired every 3 min during the first 30 min of hydration and subsequently at 1 and 2 h. Diffusion-weighted profiles obtained after 30 min and 1 and 2 h were used to calculate the spatial variation of the water self-diffusion coefficient. The resulting data provide supporting evidence for the hypothesis that phenomena such as reptation are important near the glassy/rubbery interface of polymers during dissolution, while the diffusion gradually changes to Zimm type near the rubbery/solvent interface.
Snaar
J E
JE
Department of Physics, University of Nottingham, University Park, UK.
Bowtell
R
R
Melia
C D
CD
Morgan
S
S
Narasimhan
B
B
Peppas
N A
NA
D004058:Diffusion; D016503:Drug Delivery Systems; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008853:Microscopy; D008970:Molecular Weight; D011142:Polyvinyl Alcohol; D013607:Tablets; D014867:Water
D013607:Tablets; D014867:Water; D011142:Polyvinyl Alcohol