I am synthesizing a new polymer composite consisting of a polymer having molecular weight (MW) above 2,000,000 Da. Now after completing the reaction i want to make sure that this polymer is effectively conjugated with other block of polymer and to confirm that desired polymer composite has been synthesized successfully.
Not clear if this polymer conjugate/composite is supposed to be covalently linked together or if it is simply a molecular association between two polymers.
If it is covalently linked and the material is soluble you can use typical polymer characterization tools. Light scattering can give you MW, you can do size exclusion chromatography to see if it is one piece that travels through the system together - different detectors are possible: if the two components have separable UV-Vis spectra a diode array can be useful, refractive index and light scattering are generally useful in determining MW and MWD. You can also use diffusion NMR to determine if the two are connected - they will have the same diffusion coefficient! QELS can also measure diffusion coefficient but is less precise - still, if there are two components with different MW it will show up in the population analysis.
If it is a non-covalent association in solution you are a little more limited but many of the same techniques will work: diffusion NMR is particularly useful here.
If it is a solid state polymer blend interaction you can pick this up through solid state NMR using NOESY, or through peak shifts in the IR. SEM, X-Ray diffraction and some other imaging techniques (AFM, etc) may be useful to be sure it is truly a blend and not small domains of each polymer interspersed with each other (this is pretty common - more common then the formation of solid state homogeneous blends).
Thank you sir for providing me with such a clear description. I have one more question, can it be possible to use MALDI-TOF technique is this case? or is there any other mass analytical technique that could be more useful? James E Hanson
Yes, MALDI-TOF or electrospray ionization techniques can be used (electrospray only works if water soluble). These are mainly useful if you have covalently attached materials, although MALDI-TOF has been used as an analytical tool for examining non-covalent complexes ( Anal Chem. 2003 Jul 15;75(14):3385-95. )
If you are over 2,000,000 make sure your MALDI-TOF can go that high! (I should have pointed out that for SEC you need to be sure your column works for that high of a MW as well - if the pores are too small you won't get any separation!).
- Badges
- Science topic