Introduction of Temperature-Gradient Elution in Three-Dimensional Correlation Thermal Field-Flow Fractionation with Quintuple Detection for Monitoring Compositional Dynamics of Ultrahigh-Molar-Mass Poly(styrene-co-maleic anhydride).

Analogous to temperature-gradient interaction chromatography, temperature-gradient elution three-dimensional correlation thermal field-flow fractionation (TGE-3DCoTF3) coupled with quintuple-detection provides high-resolution analysis of ultrahigh-molar-mass poly(styrene-co-maleic anhydride) synthesized via biradical photoinitiation. TGE-3DCoTF3 resolves more than 3 orders of magnitude in molar-mass, cleanly separating residual monomers and oligomers from megadalton copolymers while preserving their integrity. Multidetector correlation yields molar-mass, three independent radii, intrinsic viscosity, diffusion coefficient, thermal diffusion coefficient (DT) and UV-vis spectra. Differential UV-vis absorptivity distinguishes unreacted monomers from copolymers, enabling conversion analysis. DT serves as a pseudospectroscopic probe, confirming constant styrene-to-maleic anhydride ratios and truly alternating copolymerization. Comparative analysis of "lower" and "higher" ultrahigh-molar-mass copolymers differing by a factor of 2 in degrees of polymerization reveals identical thermophoretic behavior but distinct coil compactness, evidencing transitions toward denser core-shell morphology. Collectively, TGE-3DCoTF3 offers a nondestructive, multidimensional benchmark for elucidating molar-mass, size, and compositional dynamics in polymers that challenge conventional SEC characterization.