Molar mass determination via linear regression from SEC measurements: The case of polylactide, polycaprolactone and poly(2,2‐dimethylthrimethylene carbonate)

Abstract

AbstractMolar mass correction coefficients (cc) were determined for calculating the absolute molar masses of polylactide (PLA), polycaprolactone (PCL), and poly(2,2‐dimethyltrimethylene carbonate) (PDTC) in the range of 2,5–190 kg/mol, using calibration based on polystyrene standards (PS). Linear PLAs, PCLs, and PDTCs with a wide range of molar masses were synthesized using tin (II) octoate and diol as a catalyst/initiator system. Size Exclusion Chromatography (SEC) coupled with a Refractive Index detector (SEC‐RI) or a Multi‐Angle Laser Light Scattering detector (SEC‐MALLS) was utilized to determine the relative molar mass or absolute molar mass of the samples under investigation. Additionally, for comparison, the absolute molar mass of low molar mass PLA, PCL, or PDTC was calculated based on end‐group analysis using the 1H NMR method. Correction coefficients were subsequently calculated by comparing the molar mass obtained from SEC‐MALLS and SEC‐RI. The calculated correction coefficients ranged from 0.40 to 0.87 and increased with the rising molar mass of the polymers. The derived equation could be used to evaluate the absolute molar masses from PS standards over a broad range for the analyzed polymers.