An initiator- and catalyst-free hydrogel coating process for 3D printed medical-grade poly(ε-caprolactone).

Additive manufacturing or 3D printing as an umbrella term for various materials processing methods has distinct advantages over many other processing methods, including the ability to generate highly complex shapes and designs. However, the performance of any produced part not only depends on the material used and its shape, but is also critically dependent on its surface properties. Important features, such as wetting or fouling, critically depend mainly on the immediate surface energy. To gain control over the surface chemistry post-processing modifications are generally necessary, since it's not a feature of additive manufacturing. Here, we report on the use of initiator and catalyst-free photografting and photopolymerization for the hydrophilic modification of microfiber scaffolds obtained from hydrophobic medical-grade poly(ε-caprolactone) via melt-electrowriting. Contact angle measurements and Raman spectroscopy confirms the formation of a more hydrophilic coating of poly(2-hydroxyethyl methacrylate). Apart from surface modification, we also observe bulk polymerization, which is expected for this method, and currently limits the controllability of this procedure.

Carba-closo-dodecaborate anions with two functional groups: [1-R-12-HC≡C-closo-1-CB11H10]⁻ (R = CN, NC, CO2H, C(O)NH2, NHC(O)H).

Disubstituted carba-closo-dodecaborate anions with one functional group bonded to the cluster carbon atom and one ethynyl group bonded to the antipodal boron atom were synthesized from easily accessible {closo-1-CB11} clusters. [Et4N][1-NC-12-HC≡C-closo-1-CB11H10] ([Et4N]4b) was prepared starting from Cs[12-Et3SiC≡C-closo-1-CB11H11] (Cs1c) via salts of the anions [1-HO(O)C-12-HC≡C-closo-1-CB11H10](-) (2b) and [1-H2N(O)C-12-HC≡C-closo-1-CB11H10](-) (3b). In a similar reaction sequence [Et4N][1-CN-12-HC≡C-closo-1-CB11H10] ([Et4N]7b) was obtained from Cs[1-H2N-12-HC≡C-closo-1-CB11H10] (Cs5b) by formamidation to yield [Et4N][1-H(O)CHN-12-HC≡C-closo-1-CB11H10] ([Et4N]6b) and successive dehydration. In addition, the synthesis of the isonitrile [Et4N][1-CN-closo-1-CB11H11] ([Et4N]7a) is presented. The {closo-1-CB11} derivatives were characterized by multinuclear NMR as well as vibrational spectroscopy, mass spectrometry, and elemental analysis. The crystal structures of [Et4N][1-HO(O)C-12-HC≡C-closo-1-CB11H10] ([Et4N]2b), [Et4N][1-H2N(O)C-12-HC≡C-closo-1-CB11H10] ([Et4N]3b), [Et4N][1-NC-12-HC≡C-closo-1-CB11H10] ([Et4N]4b), [Et4N][1-H(O)CHN-12-HC≡C-closo-1-CB11H10] ([Et4N]6b), [Et4N][1-CN-12-HC≡C-closo-1-CB11H10] ([Et4N]7b), and K[1-H(O)CHN-closo-1-CB11H11] ([Et4N]6a) were determined. The transmission of electronic effects through the carba-closo-dodecaboron cage was studied based on (13)C NMR spectroscopic data, by results derived from density functional theory calculations, and by a comparison to the data of related benzene and bicyclo[2.2.2]octane derivatives.