Department of Materials and Optoelectronic Science, Center for Functional Polymers and Supramolecular Materials, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan.
Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
Int J Mol Sci. 2022 Jun 24;23(13):7018. doi: 10.3390/ijms23137018.
In this study, we synthesized a poly(cyclohexene carbonate) (PCHC) through alternative ring-opening copolymerization of CO with cyclohexene oxide (CHO) mediated by a binary LZnOAc catalyst at a mild temperature. A two-dimensional Fourier transform infrared (2D FTIR) spectroscopy indicated that strong intramolecular [C-HO=C] hydrogen bonding (H-bonding) occurred in the PCHC copolymer, thereby weakening its intermolecular interactions and making it difficult to form miscible blends with other polymers. Nevertheless, blends of PCHC with poly(vinyl phenol) (PVPh), a strong hydrogen bond donor, were miscible because intermolecular H-bonding formed between the PCHC C=O units and the PVPh OH units, as evidenced through solid state NMR and one-dimensional and 2D FTIR spectroscopic analyses. Because the intermolecular H-bonding in the PCHC/PVPh binary blends were relatively weak, a negative deviation from linearity occurred in the glass transition temperatures (). We measured a single proton spin-lattice relaxation time from solid state NMR spectra recorded in the rotating frame [(H)], indicating full miscibility on the order of 2-3 nm; nevertheless, the relaxation time exhibited a positive deviation from linearity, indicating that the hydrogen bonding interactions were weak, and that the flexibility of the main chain was possibly responsible for the negative deviation in the values of .
在这项研究中，我们通过二元 LZnOAc 催化剂催化 CO 与环氧化物（CHO）的交替开环共聚反应，在温和的温度下合成了一种聚（环己烯碳酸酯）（PCHC）。二维傅里叶变换红外（2D FTIR）光谱表明，PCHC 共聚物中存在强烈的分子内[C-HO=C]氢键（H 键）相互作用，从而削弱了其分子间相互作用，使其难以与其他聚合物形成混溶性共混物。然而，PCHC 与聚（乙烯基苯酚）（PVPh）的共混物是混溶的，因为 PCHC 的 C=O 单元和 PVPh 的 OH 单元之间形成了分子间氢键，这可以通过固态 NMR 和一维和二维 FTIR 光谱分析得到证明。由于 PCHC/PVPh 二元共混物中的分子间氢键相对较弱，因此玻璃化转变温度（）出现了负偏离线性。我们从旋转框架中记录的固态 NMR 谱测量了单个质子自旋晶格弛豫时间[（H）]，表明在 2-3nm 的范围内完全混溶；然而，弛豫时间表现出正偏离线性，表明氢键相互作用较弱，主链的灵活性可能导致值的负偏离。
