Spectral Analysis of Poly(propyleneamine) Dendrimers Peripherally Modified with 1,8-Naphthalimides

Seven newly synthesized poly(propyleneamine) dendrimers, modified with 1,8-naphthalimides, have been investigated by infrared, UV-vis, and fluorescence spectroscopy. The influence of the nature of the substituents at the C-4 position of the naphthalene ring on the spectral properties of the dendrimers is discussed.     

The Review of the Catalyst System of Poly（ethylene oxide）

聚氧化乙烯（PEO）是环氧乙烷经开环聚合而成的一种多功能水溶性聚合物,性能优异,用途广泛。本文简述了聚氧化乙烯的典型特征和国内外研究进展,综述了聚氧化乙烯制备的各类催化剂体系,描述了催化剂聚合环氧乙烷的聚合机理,重点介绍了几种具有工业应用前景的催化剂体系：烷基金属催化剂体系、烷氧基金属催化剂体系和碱土金属氨化物催化痢体系。并对其技术发展和应用进行了展望。     

A Mini Review on the Functional Biomaterials Based on Poly(lactic acid) Stereocomplex

Poly(lactic acid) stereocomplex (sc-PLA) prevails over homo-poly(lactic acid)s in many aspects and showed great potential as biomaterials depending on its extraordinary biological, thermal, and mechanical properties. In the past few years, sc-PLA has gained tremendous attention as a new approach to the development of new types of functional biomaterials. This paper summarizes recent progress in the application of the concept of sc-PLA in the design and fabrication of stabilized nanoparticles and in situ gelling hydrogels for biomedical applications.     

顺磁性物质CeF3中磁化率和费尔德常数的定量计算

本文首先计及晶场对顺磁性物质CeF_3中Ce~(3+)离子4f基态和5d激发态能级的影响,进而考虑了间接交换作用有效场II_v和外磁场H_e共同作用下导致的晶场基态能级的进一步分裂,然后应用基态双能级跃迁模型定量计算了CeF_3中的比法拉第旋转θ_F,费尔德常数F和磁化率X以及它们与温度的依赖关系.计算表明,CeF_3中的磁光效应及其温度特性与Ce~(3+)离子之间的间接交换作用密切相关,在60相似文献   

Synthesis of Organosilyl-Functionalized Cage-Type Germanoxanes Containing Fluoride Ions

Eight corners of a double-four ring cage-type germanoxane, containing a fluoride ion, were successfully silylated by the combination of chlorosilanes and silazanes. Three different silyl groups, trimethylsilyl, dimethylsilyl, and dimethylvinylsilyl, were attached on the corners of germanoxane cage. The solubility and reactivity of the cage modified with dimethylvinylsilyl groups were significantly increased, allowing for further reaction. Hydrosilylation reaction between dimethylvinylsilylated cage geramanoxanes and dimethylsilylated cage siloxanes afforded porous solids. Functionalization of the corners of germanoxanes with silyl groups should provide valuable building blocks in various functional materials.     

Obtaining of a PET-CaF2 hybrid multifilament: Non-isothermal crystallization studies

Poly(ethylene terephthalate) (PET) has been mixed with fluorite (CaF₂) particles to obtain micro- and nano-composites aiming to obtain a hybrid multifilament. In first term, the use of two montanic waxes and an amide wax as dispersing agents towards the compatibilization of the inorganic and organic components of the CaF₂/PET composite were considered. To do this, non-isothermal crystallization studies by differential scanning calorimetry have been carried out. Moreover, the influence of the CaF₂ particle size and concentration on the thermal properties of the system have been also studied by this technique. Finally, the extrapolation of the results has materialised as a novel PET/CaF₂ hybrid multifilament. Thermal and mechanical properties and molecular weight of the multifilament have been as well evaluated.     

Proton exchange membrane prepared by blending polybenzimidazole with poly (aminophosphonate ester)

In this article, we report a new amorphous-crystalline polymer blend system consisting of poly (4, 4′-diphenylether-5, 5′-bibenzimidazole) (OPBI) and poly (aminophosphonate ester) (PAPE) polymers, the membranes of which were fabricated using the solution blending route. A series of blend membranes at different ratios were prepared and systematically analysed for chemical interactions, morphological changes and their physico-chemical properties studied for use as proton exchange membrane. While FT-IR spectroscopy established the hydrogen bonding interactions between N–H of OPBI and phosphonate ester group of PAPE, X-ray diffraction studies revealed the development of crystallinity in the membrane matrix. Interestingly, the gradual induction of crystallinity in an amorphous OPBI matrix was found to influence the properties of the blend membranes favourably. For instance, the blend membrane containing 25 wt% PAPE in OPBI matrix displayed the maximum property enhancement in terms of storage modulus, glass transition temperature (T_g), phosphoric acid (PA) doping level (37 mol/OPBI repeat unit) and most importantly proton conductivity (0.135 S/cm at 180 °C) which is almost twice the value for pristine OPBI (0.05 S/cm at 180 °C) under identical conditions. Although improved properties were observed at other blend ratios as well, the studies ascertain that the membrane with 25 wt% PAPE was found to be the threshold ratio up to which properties increase and beyond which i.e. at >25 wt% PAPE, there is a decrement in properties like mechanical stability and proton conductivity. An important reason for this was attributed to the creation of a right balance of amorphous and crystalline domains and appropriate intra and inter-polymer hydrogen bonding interactions in the matrix of 75/25 (OPBI/PAPE) blend membrane.     

Synthesis of new environmentally friendly poly(urethane-imide)s as an adsorbent including β-cyclodextrin cavities and attached to iron nanoparticles for removal of gram-positive and gram-negative bacteria from water samples

The presence of pathogenic bacteria in water is one of the important health concerns in the world. Herein, we report a new high-performance environmentally friendly poly (urethane-imide) (PUIm) containing β-cyclodextrin (β-CD) in its backbone to adsorb bacteria from water samples with significant heat resistance. New PUIm was prepared by bonding a diisocyanate as a new cross linking agent to β-CD and magnetic nanoparticles (MNPs). The effects of concentrations of bare polymer and polymer bounded to iron nanoparticles and contact times on the adsorption of staphylococcus aureus and Escherichia coli were considered at physiological pH. The adsorption capacity of this polymer is increased by binding it to MNPs and in addition it is possible to separate the polymer from aqueous sample with external magnetic field. A filter was also provided from polymer attached to iron nanoparticles and high percentages of bacteria were removed after filtering the real wastewater.     

NMR analysis and triad sequence distributions of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Polyhydroxyalkanoates (PHAs) are considered promising “green” alternatives to synthetic polymers because they are bio-derived, biodegradable and biocompatible. The properties of bacterial PHA copolymers depend on their microstructures, which can be modified with the use of different fermentation processes and feed materials. Thus, it is desirable to have an improved testing method for the determination of PHA microstructures. In this work, a detailed NMR analysis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) microstructure was made. Previously only two of the hydroxyvalerate ¹³C NMR peaks have been assigned at the triad level. In this work, three of the ¹³C hydroxyvalerate peaks and two of the hydroxybutyrate peaks were found to be split into four peaks each due to comonomer sequence effects. Using eight copolymer samples with a wide compositional range, we were able to assign all these peaks to B-centered and V-centered triad sequences. Through curve deconvolution, the triad intensities were determined. These triad sequence intensities can then be analyzed via both the first-order Markovian and two-component Bernoullian models to obtain more in-depth information on copolymer composition and comonomer reactivities.