Synthesis and properties of novel self-catalytic phthalonitrile monomers with aliphatic chain and their copolymerization with multi-functional fluorene-based benzoxazine monomers

• Published in: European polymer journal 2021-12, Vol.161, p.110862, Article 110862
• Main Authors: Wang, Ting, Shi, Cheng-yu, Qadeer Dayo, Abdul, Guo, Zhi-yi, Wang, Jun, Wang, Yanhui, Gorar, Athar Ali Khan, Qiu, Jian, Liu, Wen-bin
• Format: Article
• Language: English
• Subjects: Autocatalytic phthalonitrile resin; Benzoxazines; Bisphenols; Chemical synthesis; Copolymerization; Curing characteristics; Diamines; Ethylenediamine; Glass transition temperature; Imines; Monomers; Polymerization; Polymers; Reducing agents; Substitution reactions; Temperature; Thermal decomposition; Thermal properties; Thermal stability; Thermomechanical properties; Vanillin
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2021.110862

[Display omitted] •Synthesis of novel self-catalytic phthalonitrile monomers with aliphatic chain and secondary amino group (BPAA).•The polymerization process of the BPAA monomers is an autocatalytic reaction.•The BPAA monomers have good processability.•The new polymer shows better thermal properties than traditional polyphthalonitriles.•The BPAA/diethyleneglycolamine-based benzoxazine copolymer exhibited the best thermal and thermomechanical properties. A novel series of self-catalytic phthalonitrile monomers with aliphatic segments (BPAA) were synthesized via nitro nucleophilic substitution reaction of bisphenol compound and 4-nitrophthalonitrile. Bisphenol compound was reductant with secondary amine groups of Schiff base derived from the reaction of vanillin and one of the aliphatic diamine such as 1,2-ethylenediamine, 1,3-propane diamine, and 1,6-hexamethylenediamine. The curing reaction of BPAA monomers can be carried out without any catalyst. BPAA monomers showed excellent processing properties. Moreover, BPAA polymers (poly(BAPP)) showed superior thermal stabilities and higher glass-transition temperatures (Tg) (302–317 °C). The 5% thermal decomposition temperatures (T5) of poly(BAPP) and char yield (Yc) at 800 °C under nitrogen atmosphere were 352.5–410.5 °C and 61.3–66.8%, respectively. To further improve the thermal stability of poly(BAPP), BPAA monomers were modified by multi-functional fluorene-based benzoxazine monomers (MFFB) due to their excellent reaction activities. The results showed that BAPP/MFFB systems had high reaction activities and good processing behaviors. The similar thermal stabilities between BAPP and MFFB can give stable and excellent thermal stability (T5 ≥ 378 °C) to the poly(BAPP/MFFB) systems.