2. HARDNESS OF
WATER
28-OCTOBER-2013
S.T. POPOVICI

3. HARRIS 25-7
• Why and when SEC
• Limitations of SEC

4. POLYMERS SKELETAL
STRUCTURES
- Are related to mechanical propertjes/product/ lifetime etc…..

5. POLYMERS SKELETAL
STRUCTURES
- Are related to mechanical propertjes/product/ lifetime etc…..

6. DISTRIBUTIONS OF POLYMERS

7. DISSOLUTION OF POLYMERS
- Which solvent to use ??? To dissolve your sample?

8. DISSOLUTION OF POLYMERS
The Mark–Houwink equation gives a relation between intrinsic
viscosity and molecular weight :
From this equation the molecular weight of a polymer can be
determined from data on the intrinsic viscosity and vice versa.
The values of the Mark–Houwink parameters, and , depend on
the particular polymer-solvent system. For solvents, a = 0,5
value of is indicative of a theta solvent - then the solvent
starts to precipitate !!!! (not wanted)
a and K are empirically determined constants (to be found in

9. BEST SOLVENT?
- You want a sort of ideal shape of a polymer in solution (see
Flory - Nobel Price in Chemistry in 1974) – page 160
- http://www.nobelprize.org/nobel_prizes/chemistry/laureat
es/1974/flory-lecture.pdf
- Leading to a Univarsal Calibration curve (example article
below)
- http://www.nist.gov/data/PDFfiles/jpcrd273.pdf

10. HYDRODYNAMIC VOLUME
- The apparent size of the polymer in solution
- Reflects both the polymer chain itself and the solvating
molecules in inner and outer spheres
-Hydrodynamic Volume is related to an Expansion Factor, α
α = 1 is the value for the “non-expanded” polymer in the
“ideal” statistical coil having the smallest possible size
as α increases, so does the Hydrodynamic Volume of the
sample

11. SOME EXTRA INFO
http://www.shimadzu.com/an/hplc/support/lib/lctalk/55/55int
ro.html

12. INTERPRETATION OF MMD
http://www.ias.ac.in/initiat/sci_ed/resources/chemistry/MolW
eight.pdf

13. CALIBRATION CURVE OF 14
STANDARDS

14. Molecular weight and dispersion an example:
Here are:
10 chains of 100 molecular weight
20 chains of 500 molecular weight
40 chains of 1000 molecular weight
5 chains of 10000 molecular weight
Mn
Mw
Polydispersity
(10 100) (20 500) (40 1000) (5 10000)
1347
10 20 40 5
(10 100 2 ) (20 500 2 ) (40 1000 2 ) (5 10000 2 )
(10 100 ) (20 500 ) (40 1000 ) (5 10000 )
Mw
Mn
4
5390

15. EXTRA INFO (FOR THE ONES
WANTING MORE)
http://www.shodex.net/?lang=2&applic=1483
http://www.separations.us.tosohbioscience.com/ServiceSuppo
rt/TechSupport/ResourceCenter/FAQs/HPLCColumns/SizeExclu
sion/
http://www.chem.agilent.com/Library/brochures/5990-7995GPCaqueous-Apr11-9lo.pdf
15

16. HOMEWORK (IN DUO) – NOTE
NEXT SLIDE TOO
1) When would you use SEC ?
2) When wouldn’t you use SEC ?
• Make a list of examples immagine from practice!
3) Which type of detectors can you use for SEC. Which
information give these detectors? How can you kwantitate
4) Make a scheme of the method development of a procedure
for the analysis of a polymer. Choose yoursef a easy example
and describe the procedure with existing equipment !!!! .
You will discuss it during next CHR lesson. SEE NEXT SLIDE!!!!!

17. HOMEWORK (2)
5) Explain in your own words what happends if the polymer
you are injecting has a high viscosity ?? (which negative aspect
can occur, why ?)