4,4'-Oxydiphthalic Anhydride: Dianhydride Monomer and Shape Memory Properties

4,4'-Oxydiphthalic anhydride, as a vital aromatic dianhydride monomer, it is widely used to synthesize high-performance polyimides featuring outstanding thermal and mechanical stability for advanced materials.

(Co)poly(hydroxyimide)s Based on 4,4'-Oxydiphthalic anhydride

In this study, the novelty aspect was obtaining materials possessing a new chemical structure providing of their further modification’s the possibility by functionalization of hydroxyl groups. We synthesized the three (co)poly(hydroxyimide)s ((co)PIOHs) using a 4,4'-Oxydiphthalic anhydride (ODPA) and a mixture of 3,3′-dihydroxybenzidine (HAB) with 3,6-diaminodurene (D) in three different molar ratios (3/1, 1/1, and 1/3 HAB/D) and comprehensively characterized them. Thus, this research concerns their thermal (TGA and DSC), hydrophobicity (the water contact angle), and optical (UV-Vis, ultraviolet, and visible ranges of the spectrum) measurements in the solid state as a thin film on glass, as well as their mechanical and gas transport properties (permeation behavior of N2, O2, He, and CO2). For comparison, the obtained results for analogous polyimides are also presented in this paper. The polymer 4,4'-Oxydiphthalic anhydride-3,6-diaminodurene has already been described in a publication by our research group. Polyimides (ODPA-HAB and ODPA-D) were obtained via a one-step polycondensation reaction of the dianhydride (ODPA) with an equimolar amount of diamine (HAB or D) in a mixture of N-methyl-2-pyrrolidinone and o-dichlorobenzene (4:1; v:v), according to the described procedure. The reaction mixture (20% monomer concentration) was vigorously stirred for 2–3 h, gradually increasing the temperature to 180 °C. The imidization reaction was carried out in solution at 180 °C for 3.5 h.[1]

After the reaction was completed and the reaction mixture was cooled to room temperature, the polyimide was isolated from the solution by precipitation with a non-solvent. The crude product was purified by dissolving in DMF and reprecipitating. The polyimides were extracted with methanol in the Soxhlet apparatus for 2–3 days and dried in a vacuum dryer by gradually increasing the temperature to 150 °C. The assumed low gas permeability for 4,4'-Oxydiphthalic anhydride-HAB was also confirmed. Moreover, the ideal selectivity O2/N2 and CO2/N2 were calculated. The highest α O2/N2 was obtained for the compound (co)PIOH-1, and the highest α CO2/N2 for the (co)PIOH-2. The increase in the content of ODPA-D units in (co)PIOH causes a decrease in the value of α O2/N2. Here shows the correlation between ln P (ln permeability) and the inverse of the fractional free volume. Three new amorphous (co)poly(hydroxyimide)s were synthesized in different molar ratios of 4,4'-Oxydiphthalic anhydride-HAB(D) (3:1, 1:1, and 1:3) with their possible future functionalization. The obtained compounds were characterized by good solubility in common organic solvents (e.g., NMP, DMF, and DMSO), making them easier to process during application. All of these (co)PIOHs revealed the hydrophobicity. The 4,4'-Oxydiphthalic anhydride content in the molecule mainly influences the water contact angle measure.

High-Temperature-Induced Shape Memory Copolyimide

A series of polyimide (PI) films with a high-temperature-induced shape memory effect and tunable properties were prepared via the facile random copolymerization of 4,4′-oxydianiline (ODA) with 4,4′-(hexafluoroisopropyl)diphthalic anhydride (6FDA) and 4,4'-Oxydiphthalic anhydride (ODPA). The storage modulus of PI films in the rubber state is between 5.4 and 9 MPa, and E’(Tg + 20 °C) in the rubber state of ODPA-ODA, which reaches 8.89 MPa, is slightly higher than those of the other four systems. According to the rubber elasticity theory, the higher storage modulus is due to the higher crosslink density in the system. The ODPA-ODA system contains a large number of ether bonds, and the molecular chain is more flexible and prone to entanglement, so the system may have a greater physical crosslinking density. This physical crosslinking behavior of the molecular chain helps the 4,4'-Oxydiphthalic anhydride -ODA system store more elastic energy in the process of shape memory, giving the PI film a larger shape recovery force and a higher shape recovery.[2]

In summary, a series of high-temperature shape memory PI films were prepared via facile random copolymerization of ODA with 6FDA and 4,4'-Oxydiphthalic anhydride. Their thermomechanical performance, shape memory behaviors, and mechanical properties were characterized and analyzed to discuss the influence of dianhydride proportion on the structure and properties of the film. Results indicate that the shape fixity rate and shape recovery reached 98.81% and 96.77%, respectively, by carefully tuning the ratio of 6FDA and 4,4'-Oxydiphthalic anhydride in the copolymer system. After many fixing–recovery cycles, the maxima Rf and Rr of 98.88% and 98.04%, respectively, were obtained, which proved excellent shape memory performance for the PI films. All the films exhibit excellent thermal and mechanical properties when the thermal decomposition temperature is above 535 °C, and modulus and tensile strengths are higher than 2 GPa and 125 MPa. The polyimide prepared in this work is expected to be applied in the field of space expandable structures under harsh environments.

References

[1]Pająk, Agnieszka Katarzyna et al. “New (Co)poly(hydroxyimide)s Based on 4,4'-Oxydiphthalic Anhydride-Effect of Composition on Properties, Including Gas Transport Ability.” Materials (Basel, Switzerland) vol. 18,10 2193. 9 May. 2025, doi:10.3390/ma18102193

[2]Zi Y, Pei D, Wang J, Qi S, Tian G, Wu D. High-Temperature-Induced Shape Memory Copolyimide. Polymers (Basel). 2021 Sep 23;13(19):3222. doi: 10.3390/polym13193222. PMID: 34641038; PMCID: PMC8512334.

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