THE MOLECULAR-WEIGHT AND THE REFRACTIVE-INDEX MEASUREMENTS OF FRACTIONATED OLIGO(METHYL ACRYLATE) AND OLIGO(ACRYLIC ACID)

Narrow distribution of oligo(methyl acrylate)s with a degree of polyme rization (n=2 to 10) was obtained by the use of preparative gel permea tion chromatography. The ratios of weight average molecular weight (M( w)) to number average molecular weight (M(n)) were less than 1.01 for all prepared oligo(methyl acrylate)s. Oligo(acrylic acid)s (n=2-6) wer e obtained by the hydrolysis of the oligo(methyl acrylate)s. The speci fic refractive index increment (dn/dn) was apparently independent of t he degree of polymerization of prepared oligo(methyl acrylate)s and ol igo(acrylic acid)s. In the measurements of vapor pressure osmometry of the prepared oligo(methyl acrylate)s and oligo(acrylic acid)s, it was found that a calibration coefficient K increased slightly with M(n) i n benzene and in dioxane at 45-degrees-C.