A size exclusion chromatographyâmultiangle laser light scattering (SECâMALLS) method is developed for determining the molar masses of amphiphilic hyaluronan (HA), consisting of a hydrophilic polymer backbone modified to varying extents with hydrophobic, polymerizable acrylate groups. The polymers are prepared via the baseâcatalyzed esterification of HA with acrylic anhydride. Various parameters are investigated including mobile phase composition, temperature, pH, salt type, and concentration in order to find the most suitable conditions for completely dissolving the modified polymers irrespective of the degree of substitution (DS), and for suppressing secondary polymer interactions. The hydrolytic and the thermal stability of the different materials at various experimental conditions are also extensively investigated. HAs with DS varying from 0 to 3.4 are subsequently analyzed at the optimized experimental conditions for the mobile phase being DMSO/H2O 60/40(v/v) with 0.05 M LiBr and an operating temperature of 40 °C. The refractive index increments (dn/dc) of the HAs are determined and the results show a dependence of dn/dc on DS.