Polymer Size Flashcards
how is polymer size expressed
mean-square avg.
square avg. radius of gyration
mean-square avg.
distance btw chain ends (avg r^2)
linear polymers
square avg. radius of gyration
about a center of gravity
(avg s^2)
branched polymers
average molecular mass determination methods
viscometry Mv
gel permeation chromatography/size exclusion chromatography
osmometry
viscometry
dilute soln
bases characterization of a standard
determine flow time of a specific volume through a capillary
GPC
most widely used if you have $
can calculate MW, Mv, Mn
not absolute, must calibrate with MW of known polymer
uses column chromatography
how does GPC work
column packed with beads with mazes
4 different columns to separate diff sizes (high pressure)
small molecules are trapped
bigger molecules come out first
detector at the end uses UV or IR
