Thermally responsive graft copolymer of soy protein isolate and N-isopropylacrylamide: synthesis and self-assembly behavior in aqueous solution

In recent years, soy protein isolate (SPI) has attracted great attention due to its biodegradability, biocompatibility, and wide availability. It has been used in food and pharmaceutical industry such as edible films and drug delivery systems. In this study, we report the synthesis and self-assembly behavior in aqueous solution of thermally responsive graft copolymer (SPI-g-poly(N-isopropylacrylamide) (PNIPA)) of soy protein isolate and N-isopropylacrylamide in aqueous solution. SPI-g-PNIPA was synthesized in the 8 mol/l urea cushioning solution, by using ammonium persulfate as the initiator and mercaptoacetic acid as the protein unfolding agent. Laser light scattering, transmission electron microscopy, and fluorescence spectroscopy have been used to study the self-assembly behavior of SPI-g-PNIPA in aqueous solution. Above the critical micelle concentration (cmc), SPI-g-PNIPA aggregates could assemble into different structures including the simple spherical structure, spherical core–shell structure, and random coil structure, depending on the graft copolymer concentration. The graft copolymer concentration, temperature, pH value, and ionic strength were found to influence the aggregate size and morphology of SPI-g-PNIPA in aqueous solution. With increasing ionic strength, the aggregate size increases. However, pH value, SPI-g-PNIPA concentration, and temperature have complicated influences on the aggregate size. The lower critical solution temperature of the SPI-g-PNIPA at pH 8.5 is 36 °C. The method of intrinsic fluorescence spectroscopy was used for the first time to determine the cmc value of SPI-g-PNIPA in aqueous solution.     

An improved procedure for the three‐component synthesis of benzo[g]chromene derivatives using basic ionic liquid

A basic ionic liquid, 1‐butyl‐3‐methyl imidazolium hydroxide ([bmim]OH), efficiently promotes a one‐pot, three‐component condensation of aromatic aldehydes, malononitrile or ethyl cyanoacetate, and 2‐hydroxy‐1,4‐naphthoquinone to produce 4‐aryl‐5,10‐dihydro‐4H‐benzo[g]chromene‐5,10‐dione derivatives in high yields at room temperature. This reaction does not involve any hazardous organic solvent and toxic catalyst. The ionic liquid is recovered and recycled for subsequent reactions. Moreover, this protocol has the advantages of easy work‐up, short reaction time, high yields, and environmentally benign procedure compared with the reported methods. J. Heterocyclic Chem., (2011).     

Pyrenylamine‐functionalized aromatic polyamides as efficient blue‐emitters and multicolored electrochromic materials

A series of novel aromatic polyamides with pyrenylamine in the backbone were prepared from a newly synthesized dicarboxylic acid monomer, N,N‐di(4‐carboxyphenyl)‐1‐aminopyrene, and various aromatic diamines via the phosphorylation polyamidation technique. These polyamides were readily soluble in many organic solvents and could be solution‐cast into tough and amorphous films. They had useful levels of thermal stability with glass‐transition temperatures in the range of 276–342 °C and 10% weight loss temperatures in excess of 500 °C. The dilute N‐methyl‐2‐pyrrolidone (NMP) solutions of these polymers exhibited fluorescence maxima around 455–540 nm with quantum yields up to 56.9%. The polyamides also showed remarkable solvatochromism of the emission spectra. Their films showed reversible electrochemical oxidation and reduction accompanied by strong color changes from colorless neutral state to purple oxidized state and to yellow reduced state. The polyamide 4g containing the pyrenylamine units in both diacid and diamine sides exhibited easily accessible p‐ and n‐doped states, together with multicolored electrochromic behaviors. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

A facile pathway for the fast synthesis of colloidal crystal‐loaded hydrogels via frontal polymerization

In this work, a dually sensitive colloidal crystal (CC)‐loaded hydrogel has been synthesized via frontal polymerization (FP) in a facile and rapid way. First, a polystyrene CC film was fabricated by vertical deposition on the inner wall of a test tube. Then, a mixture of acrylic acid (AAc), 2‐hydroxyethyl methacrylate (HEMA), and glycerol along with the initiator and crosslinker was added to this test tube to carry out FP, resulting in the formation of CC‐loaded hydrogel. The influence of the mass ratios of HEMA/AAc on front velocity and temperatures were studied. The swelling behavior, the morphology, and the stimuli‐responsive behavior of the CC‐loaded hydrogels prepared via FP were thoroughly investigated on the basis of swelling measurement, scanning electron microscopy, and reflection spectra. Results show that the as‐prepared CC‐loaded hydrogels exhibit excellent dual sensitivity to both methanol concentrations and pH values with very short response time, which can be observed visually without the aid of instruments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and chiroptical properties of chiral binaphthyl‐containing polyfluorene derivatives

New chiral binaphthyl‐containing polyfluorene (PF) derivatives, PFOH , PFMOM , and PFP , bearing different binaphthyl units ((S)‐2,2′‐bis(methoxymethoxy)‐1,1′‐binaphthyl for PFMOM , (S)‐1,1′‐binaphthyl‐2,2′‐diol for PFOH , and (S)‐2,2′‐bis(diphenylphosphinyl)‐1,1′‐binaphthyl for PFP ) in the backbone have been designed and synthesized through Pd‐catalyzed Suzuki polycondensation. Their properties have been investigated in detail by ¹H NMR, ¹³C NMR, TGA, DSC, UV–vis, photoluminescence (in solutions, in thin films before and after annealing), and circular dichroism (CD) spectroscopic methods compared with poly(9,9‐dihexylfluorene‐2,7‐diyl) ( PF ). The resulting copolymers possessed excellent solubility in organic solvents and emitted strong blue light. The phosphine oxide‐containing copolymers PFP and PFMOM exhibited higher quantum yields and better thermal spectral stability in comparison with PF . All the copolymers exhibited obviously the linearly polarized photoluminescent properties both in solutions and in solid states. High emission polarization ratios (R_PL) of PFP were observed with no obvious decrease upon thermal annealing. In addition, investigation of the CD spectroscopic properties of these copolymers in THF solutions indicated that the chirality of the binaphthyls could be transferred to the whole PF backbone. All these results demonstrated that introduction of the chiral binaphthyls, particularly BINAPO, into the backbone could effectively improve the performances of the copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

聚邻氨基苯酚接枝聚己内酯的合成与表征

以邻氨基苯酚为起始原料,合成了一新型接枝聚合物--聚邻氨基苯酚接枝聚己内酯(POAP-gPCL).利用核磁共振仪、红外光谱仪、X射线衍射仪、热重分析仪、电化学测试仪和紫外可见光谱仪等分析手段对聚邻氨基苯酚和聚己内酯接枝的聚邻氨基苯酚进行了结构和性能的表征.结果表明,与聚邻氨基苯酚相比,接枝聚合物表现出较好的热稳定性和电...     

Coulomb traction on a penny-shaped crack in a three dimensional piezoelectric body

The axisymmetric problem of a penny-shaped crack embedded in an infinite three-dimensional (3D) piezoelectric body is considered. A general formulation of Coulomb traction on the crack surfaces can be obtained based on thermodynamical considerations of electromechanical systems. Three-dimensional electroelastic solutions are derived by the classical complex potential theory when Coulomb traction is taken into account and the poling direction of piezoelectric body is perpendicular to the crack surfaces. Numerical results show that the magnitude of Coulomb tractions can be large, especially when a large electric field in connection with a small mechanical load is applied. Unlike the traditional traction-free crack model, Coulomb tractions induced by an applied electric field influence the Mode I stress intensity factor for a penny-shaped crack in 3D piezoelectric body. Moreover, compared to the current model, the traditional traction-free crack model always overestimates the effect of the applied electric load on the field intensity factors and energy release rates, which has consequences for 3D piezoelectric fracture mechanics.     

Godavarin K: a New Limonoid with an Oxygen Bridge between C(1) and C(29) from the Godavari Mangrove Xylocarpus moluccensis

Godavarin K ( 1 ), a new limonoid with an oxygen bridge between C(1) and C(29), was obtained from seeds of an Indian mangrove, Xylocarpus moluccensis, together with a known tetranortriterpene, 6‐de(acetyloxy)‐7‐deacetylchisocheton compound E (=(5α,7α,13α,17α)‐7‐hydroxy‐4,4,8‐trimethyl‐3‐oxocarda‐1,14‐dienolide; 2 ). The structure of godavarin K was established on the basis of spectroscopic data. In addition, the confusion of ¹H‐ and ¹³C‐NMR data for compound 2 in previous literature was clarified.