Characterization of novel thermoplastic polymers with phenolphthalein in their backbone chains

Abstract

Different molecular weight phenolphthalein poly(ether ketone) (PEK-C) and phenolphthalein poly(ether sulfone) (PES-C) fractions in chloroform (CHCl3) were studied by static and dynamic laser light scattering (LLS). The dynamic LLS revealed that both the PEK-C and PES-C samples contain some large polymer clusters formed in the process of polymerization. These large clusters can be removed by filtering the solution with a 0.1-μm filter. The positive second virial coefficient (A2) shows that CHCl3 is a good solvent for these polymers at room temperature. The persistence length and the Flory characteristic ratio of these polymers in CHCl3 at 25°C are ∼2 nm and ∼3, respectively, which indicate that these polymer chains are flexible. A combination of static and dynamic LLS results, namely the weight-average molecular weight from static LLS and the line-width distribution from dynamic LLS, lead to two calibrations between the translational diffusion coefficient (D) and molecular weight (M): D = 2.20 × 10−4 M−0.56 for PEK-C and D = 2.45 × 10−4 M−0.55 for PES-C in CHCl3. Using these calibrations, we are able to estimate not only the molecular weight distributions of these fractionated polymers, but also unfractionated PEK-C and PES-C samples.