Low-Density, Semicrystalline Poly(phenylene sulfide) Aerogels Fabricated Using a Benign Solvent
Low-Density, Semicrystalline Poly(phenylene sulfide) Aerogels Fabricated Using a Benign Solvent
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DOI：
10.1021/acsapm.3c01171
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发表时间：
2023-09
影响因子：
5
通讯作者：
Garrett F. Godshall;G. Spiering;Erin R. Crater;R. Moore
中科院分区：
文献类型：
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作者：
Garrett F. Godshall;G. Spiering;Erin R. Crater;R. Moore
利用热诱导相分离工艺，首次以1,3-二苯丙酮（DPA）为良性溶剂制备了聚苯基硫化物（PPS）热可逆凝胶。PPS/DPA相图揭示了可结晶聚合物在良好溶剂中经常观察到的固液分离机制。利用测定Flory-Huggins相互作用参数χ的两种不同方法来了解控制相行为的聚合物-溶剂相互作用。采用实验方法，拟合熔点下降曲线与实验PPS/DPA熔点数据，得到χ = 0.41的交互参数。利用PPS公认的Hansen溶解度参数和通过基团贡献法计算的DPA参数，估计聚合物-溶剂相互作用参数为χ = 0.49。两种方法的合理一致性表明PPS与DPA具有良好的相互作用，并验证了计算的DPA溶解度参数。在低于225°C的温度下凝胶化后，随后通过冷冻干燥将溶剂抽离，得到低密度为0.11至0.25 g/cm3的气凝胶，体积孔隙率为92.3至82.2%。PPS气凝胶的物理性能与聚醚醚酮（PEEK）气凝胶相当。超小到广角x射线散射（USAXS/SAXS/WAXS）曲线显示出有序的、层次分明的形貌，具有尖锐的界面，其中微观结构由堆叠的片层的半结晶聚集体组成。扫描电子显微镜显微照片显示，PPS气凝胶具有高度多孔性，层状堆叠呈细长、相互连接的原纤维形式。气凝胶密度随压缩模量的幂律缩放表明，相互连接的层状聚集体倾向于在压缩中弯曲和/或屈曲，其方式类似于开孔泡沫中的支撑变形。尽管PPS气凝胶具有相似的物理性质，但由于其网状形态，在相同密度下，PPS气凝胶的模量比PEEK气凝胶高。
Utilizing a thermally induced phase separation process, poly(phenylene sulfide) (PPS) thermoreversible gels are developed using for the first time a benign solvent, 1,3-diphenylacetone (DPA). The PPS/DPA phase diagram revealed a solid–liquid phase separation mechanism often observed with crystallizable polymers in good solvents. Two different methods of determining the Flory–Huggins interaction parameter, χ, were utilized to understand the polymer–solvent interactions that govern the phase behavior. Using an experimental approach, a melting point depression curve was fit to experimental PPS/DPA melting point data, revealing an interaction parameter of χ = 0.41. Using accepted Hansen solubility parameters of PPS and calculated parameters for DPA via a group contribution method, the polymer–solvent interaction parameter was estimated to be χ = 0.49. The reasonable agreement between both methods indicates good interactions between PPS and DPA and verifies the calculated solubility parameters for DPA. Upon gelation at temperatures below 225 °C, subsequent solvent evacuation via freeze–drying yields aerogels with low densities ranging from 0.11 to 0.25 g/cm3and volumetric porosities ranging from 92.3 to 82.2%. The physical properties of the PPS aerogels were found to be comparable to similar aerogels made from poly(ether ether ketone) (PEEK). Ultra-small to wide-angle X-ray scattering (USAXS/SAXS/WAXS) profiles reveal an ordered, hierarchical morphology with sharp interfaces, whereby the microstructure is composed of semicrystalline aggregates of stacked lamella. Scanning electron microscopy micrographs indicate that the PPS aerogels are highly porous and that the lamellar stacks take the form of elongated, interconnected fibrils. Power-law scaling of aerogel density with compressive modulus suggests a tendency of the interconnected lamellar aggregates to bend and/or buckle in compression in a manner similar to strut deformation in open-celled foams. Despite their similar physical properties, PPS aerogels demonstrated higher moduli than PEEK aerogels at comparable densities due to their network-like morphology.