Vol.:(0123456789) Polymer Bulletin https://doi.org/10.1007/s00289-020-03161-z 1 3 ORIGINAL PAPER Hydrophilic modifcation and cross‑linking of polystyrene using the synthesized N,N′‑(hexane‑1,6‑diyl)diacrylamide Seyedeh Mahnaz Modarresi‑Saryazdi 1,2  · Shahrzad Rahmani 3  · Payam Zahedi 4 Received: 10 August 2019 / Revised: 21 February 2020 / Accepted: 9 March 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract The aim of this work was to synthesize a novel hydrophilic structure based on poly- styrene (PS) cross-linked by using N,N′-(hexane-1,6-diyl)diacrylamide (HDBPA). FT-IR was carried out for chemical structure characterization of HDBPA and cross- linked samples. In addition to FT-IR, 1 H NMR was also applied on HDBPA for more investigations. The results showed that HDBPA was synthetized through a condensation reaction, and consequently, it could successfully cross-link PS struc- ture. Moreover, the determination of nitrogen content in HDBPA within PS network was investigated by means of elemental analysis. Afterward, the reactivity ratios between HDBPA and styrene were calculated via Fineman–Ross equation in which the obtained values were 0.66 and 0.23, respectively. On the other hand, by add- ing the HDBPA to PS the water contact angle was decreased from 73.6° to 57.4°, thereby proving the indispensable role of the cross-linking agent on hydrophilicity of the samples. Finally, the thermal behavior of the samples was studied using DSC and TGA analyses. According to DSC thermograms, there was a shift in T g up to 30 °C for the samples with cross-linking densities ranging from 2.5 to 20 mol.%. In regard to the thermal stability of the cross-linked samples, the TGA curves revealed a reduction in this property owing to the presence of amide groups in HDBPA through the PS structure. Keywords Polystyrene · Diacrylamide · Cross-linking · Hydrophilicity · Thermal behavior · Reactivity ratio * Shahrzad Rahmani Rahmani.sh@nit.ac.ir 1 Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, P.O. Box: 15875-4413, Tehran, Iran 2 Department of Material Science and Engineering, Monash University, Melbourne, Australia 3 Department of Chemical Engineering, Babol Noshirvani University of Technology, P.O. Box: 47148-71167, Babol, Iran 4 Nano-Biopolymers Research Laboratory, School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box: 11155-4563, Tehran, Iran