The MW (g/mol) of Poly(methylmethacrylate) (PMMA) for artificial tooth was calculated by Zimm plot method (batch) and GPC/MALS and the results were compared between the two. The Zimm plot method is to calculate the average absolute molar mass directly, without any separation. On the other hand, GPC/MALS is the method to make a size exclusion first then detect the absolute molecular weights and calculate the average. As a result, both values are almost the same. Zimm plot method can calculate the second virial coefficient, but it can’t measure the molecular weight distribution. However, combining these two methods can acquire more information and facilitate the characterization of high polymer in a steadier way. 2-mL sample loop was used for the Zimm plot analysis and the plateau was measured by flow injection. This method has less noise and enables the Zimm plot measurement in a good reproducibility in approximately 30 minutes.


Sample : Poly(methyl methacrylate)

Result :

 
                (Zimm plot)         (GPC/MALS)
Concentration  : 0.09 % to 0.41 %    0.230 %
Injection vol. : 2 mL                100 µL
Column         : No column           Shodex GPC KF-806L (8.0 mm I.D. x 300 mm)
Eluent         : THF                 THF
Flow rate      : 1.0 mL/min          1.0 mL/min
Detector       : MALS          　    MALS + RI

Data provided by Assoc. prof. Seiichiro KONDO, School of Dentistry, Hokkaido University