含铵根离子等规聚丙烯离聚体的合成及性能研究

合成了一系列高分子量、窄分子量分布且高等规度,含有不同―NR_3~+X~-离子基团含量的聚丙烯离聚体(iPP-NR_3~+X~-).以PP/IUD共聚物作为反应中间体,与三乙胺或N-甲基咪唑氨化得到聚丙烯离聚体.通过离子交换反应制备不同反离子的N-甲基咪唑聚丙烯离聚体,包括双三氟甲基磺酰亚胺根离子(Tf_2N~-)、四氟硼酸根离子(BF_4~-)和六氟磷酸根离子(PF_6~-).热重分析结果发现N-甲基咪唑聚丙烯离聚体的热稳定性明显优于三乙胺聚丙烯离聚体,表明不含β-H的N-甲基咪唑聚丙烯离聚体具有较高的热稳定性.同时,聚丙烯离聚体的表面亲水性得到明显改善.并且,聚丙烯离聚体的断裂伸长率也得到显著提高,最高达到900%.比较不同反离子聚丙烯离聚体的屈服强度和断裂强度发现I~-聚丙烯离聚体具有最优的力学性能.     

Stable,High‐Molecular‐Weight Poly(phthalaldehyde)

Low ceiling temperature, thermodynamically unstable polymers have been troublesome to synthesize and keep stable during storage. In this study, stable poly(phthalaldehyde) has been synthesized with BF₃‐OEt₂ catalyst. The role of BF₃ in the polymerization is described. The interaction of BF₃ with the monomer is described and used to maximize the yield and molecular weight of poly(phthalaldehyde). Various Lewis acids were used to investigate the effect of catalyst acidity on poly(phthalaldehyde) chain growth. In situ nuclear magnetic resonance was used to identify possible interactions formed between BF₃ and phthalaldehyde monomer and polymer. The molecular weight of the polymer tracks with polymerization yield. The ambient temperature stability of poly(phthalaldehyde) was investigated and the storage life of the polymer has been improved. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1166–1172     

Synthesis and properties of novel soluble poly(amide‐imide)s with different pendant substituents

Two types of novel fluorinated diimide‐diacid monomers—[2,2′‐(4,4′‐(3′‐methylbiphenyl‐2,5‐diyl)bis(oxy)bis(3‐(trifluoromethyl)‐4,1‐phenylene))bis(1,3‐dioxoisoindoline‐5‐carboxylic acid)] (III) and [2,2′‐(4,4′‐(3′‐(trifluoromethyl)biphenyl‐2,5‐diyl)bis(oxy)bis(3‐(trifluoromethyl)‐4,1‐phenylene))bis(1,3‐dioxoisoindoline‐5‐carboxylic acid)] (IV)—were respectively designed and prepared by the condensation of diamines I and II with two molar equivalents of trimellitic anhydride. From both diimide‐diacids, two series of novel poly(amide‐imide)s (PAIs) (IIIa–IIIe and IVa–IVe) bearing different pendant groups were prepared by direct polymerization with various aromatic diamines (a–e). All the PAIs had a high glass transition temperatures (T_gs, 232–265 °C), excellent thermal stability (exhibiting only 5% weight loss at 493–542 °C under nitrogen) and good solubility in various organic solvents due to the introduction of the bulky pendant groups. The cast films of these PAIs (80–90 μm) had good optical transparency (73–81% at 450 nm, 85–88% at 550 nm and 87–89% at 800 nm) and low dielectric constants (2.65–2.98 at 1 MHz). The spin‐coated films of these PAIs presented a minimum birefringence value as low as 0.0077–0.0143 at 650 nm and low optical absorption at the near‐infrared optical communication wavelengths of 1310 and 1550 nm. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3243–3252     

The chemical bonding and spectral assignments of rhodium(III)‐catalyzed closo‐dodecaborate complexes: Ab initio study

The chemical bonding and spectral assignments of rhodium(III)‐catalyzed closo‐dodecaborate (RhCD) complex are systematically studied using the density functional theory calculations. It is found that the calculated main bond lengths of framework are in good agreement with experimental X‐ray observation, and the pronounced hybridization of B‐2p and Rh‐4d states is responsible for the structural stability, reflected by the large dissociation energy and HOMO–LUMO energy gap. The AdNDP chemical bonding analysis indicates that the RhCD complex can be stabilized by two H‐bridged 3c‐2e σ‐bonds (B‐H‐Rh triangles). Additionally, the theoretical calculations reproduce well the main experimental IR spectrum, and the characteristic peaks are properly assigned. These results will be helpful for further insight into the unique electronic structure of the species, and provide valuable references for potential applications in novel materials.     

In situ PM‐IRRAS studies of organothiols and organosilane monolayers–ZnO interfaces at high water activities

In situ photoelastic‐modulated Fourier transform infrared reflection absorption spectroscopy has been applied for the investigation of interfacial stability of organothiol and organosilane monolayer films on nanocrystalline zinc oxide thin films. It has been shown that for octadecyltriethoxysilane films, exposure to high water activities results in physisorption of water in the cross‐linked film. This high water activity at the interface leads to a reversible wet de‐adhesion of the interfacial silanol groups from the ZnO surface. However, the organothiol seems to form a denser monolayer and a stable by S–Zn bond that is resistant to the competition with adsorbed water. The reversible attachment for cross‐linked organosilanol films has been demonstrated for the first time by means of an in situ spectroscopic method on model ZnO surfaces. Copyright © 2016 John Wiley & Sons, Ltd.     

Amphiphilic Imbalance and Stabilization of Block Copolymer Micelles on‐Demand through Combinational Photo‐Cleavage and Photo‐Crosslinking

An amphiphilic block copolymer of poly(ethylene oxide)‐b‐poly((N‐methacryloxy phthalimide)‐co‐(7‐(4‐vinyl‐benzyloxyl)‐4‐methylcoumarin)) (PEO₄₅‐b‐P(MAPI₃₆‐co‐VBC₄)) is designed to improve the micellar stability during the photo‐triggered release of hydrophobic cargoes. Analysis of absorption and emission spectra, solution transmittance, dynamic light scattering, and transmission electron microscopy supports that polymer micelles of PEO₄₅‐b‐P(MAPI₃₆‐co‐VBC₄) upon the combinational irradiation of 365 and 254 nm light can be solubilized through the photolysis of phthalimide esters and simultaneously crosslinked via the partially reversible photo‐dimerization of coumarins. The photo‐triggered release experiment shows that the leakage of doxorubicin molecules from crosslinked micelles can be predictably regulated by controlling the irradiation time of 365 and 254 nm light.

     

Preparation and Stability Evaluation of Size‐Controllable PDHCA‐β‐CD Nanoparticles as Drug Carrier

A novel biocompatible polymer was prepared by grafting the derivate of β ‐cyclodextrin (6‐SH ‐β ‐CD ) onto poly(3,4‐dihydroxycinnamic acid) (PDHCA ) via Michael addition. PDHCA ‐β ‐CD nanoparticles were prepared by the self‐assembly of amphiphilic PDHCA ‐β ‐CD polymer with N,N ‐dimethylformamide (DMF ) as good solvent and water as poor solvent. The PDHCA ‐β ‐CD nanoparticles were monodispersed with spherical morphology as shown in the scanning electron microscopic (SEM ) images in accord with the result of dynamic light scattering (DLS ) measurement. The size of the nanoparticles could be controlled from 60 to 180 nm by tuning the grafting degree (GD ) of PDHCA ‐β ‐CD polymer and also significantly influenced by the amount of water used during the process. These as‐prepared nanoparticles were stable without any significant change in the particle size after six‐months’ storage and even after being irradiated by UV at λ >280 nm for hours. The formation mechanism of PDHCA ‐β ‐CD nanoparticles was explored. The content of doxorubicin (DOX ) loaded onto the nanoparticles was up to 39% with relatively high loading efficiency (approximately 78.8% of initial DOX introduced was loaded). In vitro release studies suggested that DOX released slowly from PDHCA ‐β ‐CD nanoparticles. These features strongly support the potential of developing PDHCA ‐β ‐CD nanoparticles as carriers for the controlled delivery of drug.