Molar Mass Distribution and Chemical Composition Distribution of PS-b-PMMA Block Copolymers Determined by Diffusion Ordered Spectroscopy

It is well-known that the molar mass distribution (MMD) of block copolymers will be performed by size exclusion chromatography (SEC) with two calibrated detectors to determine the molar mass distribution via the average chemical composition distribution (CCD) of the block copolymers. This work will present a new way to determine the molar mass distribution via the average chemical composition of block copolymers by using the nuclear magnetic resonance (NMR) based diffusion ordered spectroscopy (DOSY) with inverse Laplace transform (ILT). This DOSY approach allows the determination of the MMD of copolymers in the bulk sample. It will be shown that DOSY can be enabled for the determination of the MMD via the CCD of block copolymers by adopting the dual detector SEC approach to DOSY. Therefore, several PS-b-PMMA block copolymers were analyzed by this new DOSY approach as well as the dual SEC-UV-RI detection. The DOSY results of the MMD and CCD are in good agreement with the common SEC-RI-UV dual detector copolymer analysis.