Multidetector Thermal Field-Flow Fractionation for the Characterization of Vinyl Polymers in Binary Solvent Systems

Abstract

Thermal field-flow fractionation (ThFFF) is applied to the characterization of vinyl polymers such as poly(vinylcyclohexane) (PVCH) in terms of size, molar mass and chemical composition. It is shown by 1 H NMR that, although limited, ThFFF using single component solvents can separate polystyrene (PS) and its hydrogenated product, PVCH, according to differences in molecular microstructure. Different from single component solvents, binary solvent systems of cyclohexane and methyl ethyl ketone can provide an additional driving force (in the form of solvent partitioning) to dramatically improve the separation of PS and PVCH by ThFFF. It is found that the separation of PS and PVCH improves with increasing methyl ethyl ketone content in the mobile phase up to 30 vol %. Additionally, it is shown that the compositional distribution of PVCH in the binary solvent systems can be obtained by the online coupling of infrared spectroscopy to ThFFF.

The Role of Solubility in Thermal Field Flow Frac-tionation – A Revisited Theoretical Approach for Tuning the Separation of Chain-Walking Polymerized Polyethylene

“…In fact, such mixture effects can be also used to improve ThFFF separations. 81,82 The retention in ThFFF is a result of the interplay between DT and D. In particular D is strongly dependent on the mean layer temperature which corresponds to the retention time why δD for this cwPE appears to be significantly lower than reported for regular types of PE (δD = 18 MPa 0.5 for HDPE or LDPE δD = 17.6 MPa 0.5 )? 83 The trend to lower δD is also found for iso-alkanes in comparison to their n-derivates.…”

The Role of Solubility in Thermal Field-Flow Fractionation: A Revisited Theoretical Approach for Tuning the Separation of Chain Walking Polymerized Polyethylene

“…In the case of alkane mixtures, significant solvent effects observed in other solvent mixtures are not expected. In fact, such mixture effects can be also used to improve ThFFF separations. , …”

“…In fact, such mixture effects can be also used to improve ThFFF separations. 83,84 The retention in ThFFF is a result of the interplay between D T and D. In particular, D is strongly dependent on the mean layer temperature, which corresponds to the retention time measured in ThFFF. Hence, the question arises: to which extent does the solubility influences D T ?…”

Thermal Field‐Flow Fractionation for the Investigation of the Thermoresponsive Nature of Star and Linear Polystyrene

“…This interplay between the two mass transport processes forms the basis for the compositional (through D T ) or size‐based (through D ) separation capabilities of ThFFF . For a more in‐depth explanation of the ThFFF principles, the reader is referred to several articles addressing the subject …”

“…[19,24] For a more in-depth explanation of the ThFFF principles, the reader is referred to several articles addressing the subject. [24][25][26] Despite the remarkable separation capabilities of ThFFF only a few studies have addressed the characterization of star polymers by ThFFF. To date, it has been shown that ThFFF can be used to separate star and linear polymers based on differences in hydrodynamic size and that the chemical composition distributions as well as the number of arms of miktoarm star copolymers can be determined.…”