1 research outputs found
High Temperature Quadruple-Detector Size Exclusion Chromatography for Topological Characterization of Polyethylene
Modifying
material properties in simple macromolecules such as
polyethylene (PE) is achieved by different connection modes of ethylene
monomers resulting in a plurality of possible topologies–from
highly linear to dendritic species. However, the challenge still lies
within the experimental identification of the topology and conformation
of the isolated macromolecules because of their low solubility, which
demands methods with specific solvents and high operating temperatures.
Additionally, a separation technique has to be coupled to different
detection methods to meet the specific demands of the respective characterization
goal. In this work, we report a quadruple-detector high temperature
size exclusion chromatography (HT-SEC) system which contains online
multiangle laser light scattering, dynamic light scattering, differential
viscometry, and differential refractometry detectors. Quadruple-detector
HT-SEC was successfully applied to explore the full range of physical
parameters of various PE samples with different branching topologies
ranging from highly linear macromolecules, polymers with moderate
level of branching, to highly branched PEs with hyperbranched structure.
This method is a useful tool not only to investigate molecular weight,
mass distribution, and size but also to enable access to important
factors which describe the conformation in dilute solution and branching
density