AN1005: Identifying Polymer Short-Chain Branching

Polymer branching is an important molecular parameter since it affects various macroscopic polymer properties such as crystallinity, melting temperature, toughness, ductility, and optical clarity. Two types of branching are recognized: long-chain branching (LCB) wherein the molar mass of the branches is greater than the entanglement molar mass, and short-chain branching (SCB) wherein the molar mass of the branches is smaller than the entanglement molar mass.

Size-exclusion chromatography with multi-angle light scattering (SEC-MALS), alone or in conjunction with a viscometer (SEC-MALS-IV) is often used to characterize LCB in macromolecules. A simple means of distinguishing between LCB and SCB would be of great value to polymer scientists. This application note describes how SEC-MALS identifies and quantifies these two properties.