Design and mediated hydrogen bonding strength of Poly(styrene-alt- alt- N - (ethyl-4-hydroxyphenyl)maleimide)-4-hydroxyphenyl)maleimide) copolymer to enhance miscibility with hydrogen bonded acceptor homopolymers

In this study, the monomer N -(ethyl-4-hydroxyphenyl)maleimide (TyHPMI) was synthesized from tyramine and maleic anhydride. Subsequently, free radical copolymerization was used to prepare the poly(S-alt-TyHPMI) alt -TyHPMI) alternating copolymer by reacting TyHPMI with styrene. We confirmed the chemical structure using Fourier transform infrared (FTIR), 1 H and 13 C nuclear magnetic resonance (NMR). The sequence distribution of the poly (S-alt-TyHPMI) alt -TyHPMI) alternating copolymer was analyzed using mass-analyzed laser desorption ionization/time-of-flight (MALDI-TOF) mass spectrometry. Differential scanning calorimetry (DSC) measurements showed a single glass transition temperature (Tg) T g ) across various weight fractions of binary blended systems containing strong hydrogen-bonded acceptors, such as poly(S-alt-TyHPMI)/poly(4-vinyl alt -TyHPMI)/poly(4-vinyl pyridine) (P4VP) and poly(vinyl pyrrolidone) PVP, implying full miscibility. The T g values predicted by kwei equation for the poly (S-alt-TyHPMI)/P4VP alt -TyHPMI)/P4VP and poly(S-alt-TyHPMI)/PVP alt -TyHPMI)/PVP blends show a positive deviation from linearity. This deviation is due to the short alkyl chain reinforcing the addition of acidic TyHPMI units, which enhances intermolecular hydrogen bonding between the pyridyl or C=O =O groups and the OH units of the TyHPMI segment. As a result, FTIR spectral analyses indicate that the intermolecular hydrogen bonding between pyridyl and C=O =O groups is stronger in the poly(S-alt-TyHPMI) alt -TyHPMI) copolymer compared to the poly(S-alt-HPMI) alt -HPMI) copolymer. This is supported by the larger ratio of the inter/self-association equilibrium constant (KA/KB) K A / K B ) value.