Niehoff Ansgar, Mantion Alexandre, McAloney Richard, Huber Alexandra, Falkenhagen Jana, Goh Cynthia M, Thünemann Andreas F, Winnik Mitchell A, Menzel Henning
Institute for Technical Chemistry, Braunschweig University of Technology, Hans-Sommer-Straße 10, 38106 Braunschweig, Germany.
Colloid Polym Sci. 2013 Jun;291(6):1353-1363. doi: 10.1007/s00396-012-2866-9. Epub 2012 Dec 14.
The synthesis, characterization, self-assembly, and gel formation of poly(γ-benzyl-l-glutamate) (PBLG) in a molecular weight range from ca. 7,000-100,000 g/mol and with narrow molecular weight distribution are described. The PBLG is synthesized by the nickel-mediated ring-opening polymerization and is characterized by size-exclusion chromatography coupled with multiple-angle laser light scattering, NMR, and Fourier transform infrared spectroscopy. The self-assembly and thermoreversible gel formation in the helicogenic solvent toluene is investigated by transmission electron microscopy, atomic force microscopy, small-angle X-ray scattering, and synchrotron powder X-ray diffraction. At concentrations significantly below the minimum gelation concentration, spherical aggregates are observed. At higher concentrations, gels are formed, which show a 3D network structure composed of nanofibers. The proposed self-assembly mechanism is based on a distorted hexagonal packing of PBLG helices parallel to the axis of the nanofiber. The gel network forms due to branching and rejoining of bundles of PBLG nanofibers. The network exhibits uniform domains with a length of 200 ± 42 nm composed of densely packed PBLG helices.
描述了分子量范围约为7,000 - 100,000 g/mol且分子量分布窄的聚（γ-苄基-L-谷氨酸）（PBLG）的合成、表征、自组装及凝胶形成过程。PBLG通过镍介导的开环聚合反应合成，并通过尺寸排阻色谱结合多角度激光光散射、核磁共振和傅里叶变换红外光谱进行表征。利用透射电子显微镜、原子力显微镜、小角X射线散射和同步辐射粉末X射线衍射研究了在螺旋性溶剂甲苯中的自组装和热可逆凝胶形成。在显著低于最低凝胶化浓度的浓度下，观察到球形聚集体。在较高浓度下，形成凝胶，其呈现出由纳米纤维组成的三维网络结构。所提出的自组装机制基于与纳米纤维轴平行的PBLG螺旋的扭曲六方堆积。凝胶网络是由于PBLG纳米纤维束的分支和重新结合而形成的。该网络呈现出由紧密堆积的PBLG螺旋组成的长度为200 ± 42 nm的均匀区域。
