Complex Branched Polymers for Structure–Property Correlation Studies: The Case for Temperature Gradient Interaction Chromatography Analysis
Abstract
The idiom "can't see the wood for the trees" would appear uniquely apt in describing attempts to characterize structural dispersity in complex branched polymers, especially dendritically branched polymers, by size exclusion chromatography (SEC) alone. SEC is incapable of resolving polymers with nearly identical hydrodynamic volumes which may differ in molecular weight—a particular problem in the characterization of branched polymers. This paper discusses in detail the variety of synthetic methodologies used to synthesize complex branched polymers including H-shaped polymers, comb-branched polymers, and with particular emphasis on dendritically branched polymers, also known as Cayley trees and DendriMacs. The advantages and limitations of each method are discussed, supported by a review of recent reports of temperature gradient interaction chromatography (TGIC) analysis of such polymers. With one eye to the future, recent results should provoke the polymer chemists to devise improved synthetic strategies, but it is clear that TGIC is now an indispensable technique for revealing structural dispersity in complex branched polymers and allowing teams involved in structure–property correlation studies to see "the wood and the trees".