Investigation of the Side Chain Effect on Gas and Water Vapor Transport Properties of Anthracene-Maleimide Based Polymers of Intrinsic Microporosity

• Published in: Polymers 2021-12, Vol.14 (1), p.119
• Main Authors: Caliskan, Esra, Shishatskiy, Sergey, Neumann, Silvio, Abetz, Volker, Filiz, Volkan
• Format: Article
• Language: English
• Subjects: Affinity; Aliphatic compounds; Anthracene; Aromatic compounds; Copolymers; Fourier transforms; Gases; Heat treatment; Infrared analysis; Infrared spectroscopy; Microporosity; Monomers; NMR; Nuclear magnetic resonance; Permeability; Polymers; Size exclusion chromatography; Transport properties; Water vapor
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym14010119

In the present work, a set of anthracene maleimide monomers with different aliphatic side groups obtained by Diels Alder reactions were used as precursors for a series of polymers of intrinsic microporosity (PIM) based homo- and copolymers that were successfully synthesized and characterized. Polymers with different sizes and shapes of aliphatic side groups were characterized by size-exclusion chromatography (SEC), (nuclear magnetic resonance) H-NMR, thermogravimetric (TG) analysis coupled with Fourier-Transform-Infrared (FTIR) spectroscopy (TG-FTIR) and density measurements. The TG-FTIR measurement of the monomer-containing methyl side group revealed that the maleimide group decomposes prior to the anthracene backbone. Thermal treatment of homopolymer methyl-100 thick film was conducted to establish retro-Diels Alder rearrangement of the homopolymer. Gas and water vapor transport properties of homopolymers and copolymers were investigated by time-lag measurements. Homopolymers with bulky side groups ( -propyl-100 and -butyl-100) experienced a strong impact of these side groups in fractional free volume (FFV) and penetrant permeability, compared to the homopolymers with linear alkyl side chains. The effect of anthracene maleimide derivatives with a variety of aliphatic side groups on water vapor transport is discussed. The maleimide moiety increased the water affinity of the homopolymers. Phenyl-100 exhibited a high water solubility, which is related to a higher amount of aromatic rings in the polymer. Copolymers (methyl-50 and -butyl-50) showed higher CO and CH permeability compared to PIM-1. In summary, the introduction of bulky substituents increased free volume and permeability whilst the maleimide moiety enhanced the water vapor affinity of the polymers.