Some emerging techniques in polymer mwd characterization

Routine MW analysis of polymers is generally performed in solution by Gel Permeation Chromatography. The technique, however, presents increasing difficulties in the ultra‐high and ultra‐low MW range. Moreover, GPC is not applicable to most fluorinated and»high performance«thermoplastics which require dissolution temperatures close to the polymer melting point. In response to these challenges, polymer scientists have developed new methods of MWD determination. Although these methods have not yet reached the versatility of GPC, they present potential for further development and are interesting as complementary techniques to GPC. For sparingly soluble polymers, melt viscoelastic properties have been used to obtain information on polymer MWD. Flow birefringence, based on the orientation and extension of long flexible molecular chains in a shear field, has been applied to the characterization of ultra‐high MW polymers. For low MW polymers and oligomers, the MALDI mass spectrometry technique, with its unique capabilities to resolve individual oligomers within a MWD, proves to be an interesting alternative to conventional GPC characterization.