A series of thin cyclomatrix polyphosphazene films has been prepared by interfacial polymerization of hexachlorocyclotriphosphazene (HCCP) with an aromatic biphenol. The pK_a values of the biphenol used strongly influence the properties of the hyper-cross-linked films formed. 4,4′-Dihydroxybiphenyl (BPH) and 4,4′-dihydroxydiphenyl ether (DHPE) possess pK_a values in the range of 9.4–9.6 & 10.0–10.3 for the mono- and di-ionized forms, respectively, and produce films with a lower cross-link density, whereas 4,4′-dihydroxybenzophenone (DHBP) and 4,4′-sulfonyldiphenol (BPS) feature lower pK_a values (7.4–7.6 & 8.0–8.2), resulting in films with a higher cross-link density. The difference in cross-link density is reflected in, e.g., the surface morphology and mechanical properties of the films. Mechanical stiffness has been quantitatively assessed by PeakForce QNM AFM. Lower cross-link densities result in Young's moduli with average values of 44–69 MPa, with a sharp distribution, while higher cross-link densities yield broadly distributed Young's moduli with average values of 255–306 MPa, depending on the choice of the biphenol. The surface chemistry of the films was successfully altered by post-functionalization.

中文翻译：

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环矩阵聚磷腈薄膜：六氯环三磷腈与芳香族双酚的界面聚合

通过六氯环三磷腈（HCCP）与芳香族双酚的界面聚合制备了一系列薄的环矩阵聚磷腈薄膜。所用双酚的p K _a值强烈影响所形成的超交联膜的性能。4,4'-二羟基联苯（BPH）和4,4'-二羟基联苯醚（DHPE）的单电离和二电离形式的p K _a值分别在9.4–9.6和10.0–10.3范围内，并产生膜的交联密度较低，而4,4'-二羟基二苯甲酮（DHBP）和4,4'-磺酰基二酚（BPS）的p K _a值较低（7.4–7.6和8.0–8.2），从而导致膜的更高的交联密度。交联密度的差异体现在：例如，薄膜的表面形态和机械性能。机械刚度已通过PeakForce QNM AFM进行了定量评估。较低的交联密度会导致杨氏模量的平均值为44–69 MPa，分布较尖锐；而较高的交联密度会产生分布较广的杨氏模量，平均值为255–306 MPa，具体取决于双酚的选择。通过后功能化成功改变了薄膜的表面化学性质。