Core–Shell Poly (Ionic Liquid)@Mesoporous Silica Chemiluminescent Nanoprobes for Sensitive Intracellular Hydrogen Peroxide Imaging

Despite significant developments in spatial distribution imaging of H₂O₂ as one the most important nonradical reactive oxygen species, novel background‐free, highly sensitive, and selective probes that allow intracellular sensing are still imperative. This is mainly because the fluorescent probes usually suffer some drawbacks such as, fluorescence bleaching and requirement of bulky light sources. In this study, the rational design and fabrication of a nonenzymatic nanoprobe (c‐PIL@mSiO₂) with dramatically improved sensitivity for chemiluminescent (CL) imaging of intracellular and in vivo H₂O₂ at nano molar level is presented. The limit of detection is lower than the endogenous H₂O₂ concentration, and is significantly better than that of some recently reported fluorescent and CL probes. Structurally, the nanoprobe is composed of a unique amphiphilic poly(ionic liquid) core for preserving H₂O₂ responsive reagents, and a mesoporous silica shell acts as an “exoskeleton” to provide hydrophilic nature. The multiple alternating hydrophobic and hydrophilic nanodomains of the poly(ionic liquid) core increase mass transfer dynamics, which increase the sensitivity of H₂O₂ imaging. RAW264.7 macrophages and mice models of inflammations experiment show that the c‐PIL@mSiO₂ is capable of imaging H₂O₂ intracellular and in vivo. This probe for the first time achieves CL detection of endogenous intracellular H₂O₂ without disruption of cells.     

离子液体中聚氧化乙烯(PEO)相变过程中的氢键效应

我们把Flory-Huggins模型推广应用到聚合物/离子液体体系,研究聚氧化乙烯(PEO)在离子液体[EMIM][BF_4]中相变过程中的氢键效应,理论模型考虑了三种类型氢键(Ⅰ型:PEO-[EMIM]~+氢键,Ⅱ型:PEO-[BF_4]~-氢键和Ⅲ型:[EMIM]~+-[BF_4]~-氢键)的形成,分析了三种类型的氢键分数随温度、 PEO体积分数的变化.研究发现,三种类型的氢键分数随温度的升高而减少.在较小PEO体积分数条件下,增加PEO体积分数,Ⅰ型、Ⅱ型氢键分数轻微地减小;在较大PEO体积分数条件下,增加PEO体积分数,Ⅰ型、Ⅱ型氢键分数急剧减少.Ⅲ型氢键分数随着PEO体积分数的增加而急剧降低.由于三种氢键效应,第二维里系数A_2随温度的增加而减小.通过计算分析不同分子量的PEO在[EMIM][BF_4]中的相图发现,在PEO体积分数较低的条件下,Ⅰ型、Ⅱ型和Ⅲ型氢键是PEO相变的主要驱动力;在PEO体积分数较高的条件下,Ⅰ型和Ⅱ型氢键在PEO相变过程中起到主导作用.     

Electrodeposition of Poly(3-Chlorothiophene) Film on WO3 Surfaces in an Ionic Liquid

Poly(3-chlorothiophene) (PCT) was electrochemically polymerized on the surface of tungsten oxide (WO₃) in the ionic liquid 1-butyl-3-metyllimidazolium hexafluorophosphate by a potentiodynamic method. The PCT/WO₃ films were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray analysis. Cyclic voltammetric experiment results showed that the electrochemical activity of the PCT/WO₃ composite film was significantly improved due to the contribution of unique structure and interactions between PCT and WO₃.     

The Surface Wettability and Adhesion of Poly(Ester Urethane)s and Poly(Ether Urethane)s

In this study the wetting characteristics of untreated and plasma-treated polyurethane thin films were investigated. The degree of wettability was investigated by measuring the contact angle formed between a liquid drop and the solid surface. The work of adhesion, interfacial free energy, spreading coefficient, and Girifalco–Good's interaction parameter changed significantly for plasma-treated polyurethane films. Both complete and partial wetting were analyzed from the spreading coefficient of liquid drops on the solid substrate.     

Micellization Process in Poly(Ether Urethane) Solutions

Poly(ether urethane)s containing different hard segments were investigated by viscometry, fluorescence spectra, polarizing optical microscopy, and scanning electron microscopy. The polarity dependence of the vibrational structure of the pyrene emission spectrum indicated the formation of aggregates at concentrations that are significantly below the critical concentrations that define the separation of dilute‐semidilute domains. Unlike the sample with 4,4'‐methylene diphenylene diisocyanate, the sample with 2,4‐tolylene diisocyanate in hard segments gives a fluorescence spectra in which the pyrene excimer appears. Supermolecular structures associated with the form of spherulites or of spherical micelles were detected by scanning electron microscopy. The results are discussed in correlation with viscometric data and optical microscopy.     

High Thermally Stable and Organosoluble New Poly(amide-imide)s Derived from Bis(4-trimellitimido phenoxy)phenyl Triptycene

A triptycene-containing dicarboxylic acid monomer, bis(4-trimellitimido phenoxy)phenyl triptycene, was successfully synthesized by refluxing the diamine, bis(4-aminophenoxy)phenyl triptycene with trimellitic anhydride in glacial acetic anhydride. A series of aromatic poly(amide-imide)s were prepared by condensation polymerization of the dicarboxylic acid monomer and seven different commercially available diamines. The resulting poly(amide-imide)s were soluble in various solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and pyridine. The polymers were amorphous and had inherent viscosities in the range 0.40–0.67?dL/g. These polymers had low dielectric constants ranging from 2.09 to 2.18. The glass transition temperatures of these polymers were observed between 229°C and 277°C. These polymers showed good thermal stability without significant weight loss up to 500°C. The temperatures at 10% weight loss ranged from 512°C to 570°C in nitrogen. The UV-Vis absorption spectra revealed that most of the polymers had absorption maxima around 312–348 nm, indicating the conjugation between the aromatic rings and nitrogen atoms. Solvent cast films had tensile strengths from 75 to 108?Mpa, elongates at break of 7%–9% and tensile moduli of 1.7–2.0?Gpa, indicating they were strong materials.     

Synthesis and Kinetic Study of Thermal Cycloimidization of Novel Poly(Amide Amic Acid) to Poly(Amide Imide) by Thermogravimetric Analysis

A new series of fluorinated poly(amide imide)s (PAIs) were prepared by polycondensation of diamine amic acid (DAA) with isophthaloyl, terephthaloyl, or trimellitic anhydride chloride in dimethylformamide, and their subsequent thermal cycloimidization. DAAs were obtained by reacting 4, 4′ (hexafluoroisopropylidene) diphthalic anhydride (6FDA) with diamines in dimethylformamide at 0–5°C. The kinetics of thermal cycloimidization of poly(amide amic acid) (PAA) to PAIs was investigated by thermogravimetric analysis under isothermal conditions at four different temperatures, i.e. 175, 200, 225, and 260°C, for 75 min. A generalized equation to calculate the theoretical amount of weight loss upon complete imidization, i.e. T_w % = 18Nw/R _Mw, was developed. In the above equation numeral 18 corresponds to the molecular weight of water, N is the number of water molecules, which are eliminated per repeat unit of PAA upon cycloimidization, w is the weight of PAA taken for TGA, and R _Mw is the molecular weight of the repeat unit of PAA. The polymers were characterized by FT-IR spectra. Complete cycloimidization process is discussed in terms of monomer structure (diamines and acid chlorides), effect of imidization temperature and time, types of linkages (meta or para) present, and influence of electron withdrawing groups, such as sulfone, in the monomer structure. It was observed that cycloimidization occurred at a faster rate at the beginning, up to about 30 min, and then proceeded at a slower rate till the end of curing. The thermal and thermooxidative stabilities of PAIs were also investigated in nitrogen and oxygen atmosphere.     

Formation of Ring-Banded Spherulites of Poly (L-lactide) in its Miscible Mixture with an Ionic Liquid

Incorporation of an ionic liquid, nonvolatile and thermally stable, promoted formation of ring-banded spherulites in poly (l-lactide) (PLLA) during its sol–gel transition. Their formation is correlated with low viscosity and insignificant chain entanglements in the mixtures induced by the ionic liquid. In addition to a driving force for lamellar twisting that depended on the crystallization temperatures, it is believed that reduced lamellar twisting resistance caused by the ionic liquid plays a vital role in the formation of the ring-banded spherulites of PLLA from the mixtures. This study gives further insights into the structural formation of PLLA during a sol–gel transition, which could open new opportunities to tailor the properties of ion gels based on PLLA.     

Isothermal Melt Crystallization Kinetics for Poly(Trimethylene Terephthalate)/Poly(Butylene Terephthalate) Blends

The kinetics of isothermal melt crystallization of poly(trimethylene terephthalate) (PTT)/poly(butylene terephthalate) (PBT) blends were investigated using differential scanning calorimetry (DSC) over the crystallization temperature range of 184–192°C. Analysis of the data was carried out based on the Avrami equation. The values of the exponent found for all samples were between 2.0 and 3.0. The results indicated that the crystallization process tends to be two‐dimensional growth, which was consistent with the result of polarizing light microscopy (PLM). The activation energies were also determined by the Arrhenius equation for isothermal crystallization. The values of ΔE of PTT/PBT blends were greater than those for PTT and PBT. Lastly, using values of transport parameters common to many polymers (U*=6280 J/mol, T _∞=T _g – 30), together with experimentally determined values of T _m ⁰ and T _g, the nucleation parameter, K _g, for PTT, PBT, and PTT/PBT blends was estimated based on the Lauritzen–Hoffman theory.     

Poly(allylamine) Stabilized Iron Oxide Magnetic Nanoparticles

This paper describes a new method for the dispersing and surface-functionalization of metal oxide magnetic nanoparticles (10 nm) with poly(allylamine) (PAA). In this approach, Fe₃O₄ nanoparticles, prepared with diethanolamine (DEA) as the surface capping agent in diethyleneglycol (DEG) and methanol, are ligand exchanged with PAA. This method allows the dispersing of magnetic nanoparticles into individual or small clusters of 2–5 nanoparticles in aqueous solutions. The resulting nanoparticles are water soluble and stable for months. The PAA stabilized Fe₃O₄ nanoparticles are characterized by TEM, TGA, and FT-IR. The PAA-coated Fe₃O₄ nanoparticles will allow further chemical tailoring and engineering of their surfaces for biomedical applications.     

Rheological Behavior of Blends of Poly(Phenylene Sulfide) with a Thermotropic Liquid Crystalline Aromatic Poly(Ether Ester)

A new type of thermotropic liquid crystalline aromatic poly(ether ester) (PEE) was prepared from 1,3-bis(4′-carboxyphenoxy)benzene, 1,4-diacetoxybenzene, and p-acetoxybenzoic acid through a melt transesterification process. The rheological behavior of blends of poly(phenylene sulfide) (PPS) with PEE was studied using a high-pressure capillary rheometer with the shear rate range of 50 s^?1 to 3000 s^?1. The results show that according to the range of shear rate, the flow curves of PEE/PPS blends can be divided into three zones: a first shear-thinning zone (n < 1, “n” represents non-Newtonian indexes), a shear-thickening zone (n > 1), and a second shear-thinning zone (n < 1), and the former two zones are more obvious with the increase of PEE content or elevated temperature. In the second shear-thinning zone, the PPS melt is close to a Newtonian fluid at high temperature and high shear rate; meanwhile the non-Newtonian behavior of the PPS melt at high temperature is enhanced with the addition of PEE. The apparent viscosity of PPS melts sharply dropped after adding PEE, especially at relatively low temperature and low shear rate. The curve of apparent viscosity vs. shear rate starts to flatten out after adding PEE, suggesting that the addition of PEE lowers the sensitivity of PPS to shear rate. As the content of PEE increases, the activation energy of the viscous flow, ΔE_η, of PPS decreases, which means that adding PEE weakens the temperature sensitivity of the apparent viscosity of the PPS melt. It can clearly be seen that the addition of PEE is beneficial to the processing of PPS.     

三螺旋DNA分子poly(dT)·poly(dA)·poly(dT)的构型和振动谱

我们计算了ｐｏｌｙ（ｄＴ）·ｐｏｌｙ（ｄＡ）·ｐｏｌｙ（ｄＴ）的Ｈｏｗａｒｄ模型的原子笛卡尔坐标，并利用晶格动力学方法对模型进行了简正分析。结果发现其０ Ｐ ０对称振动模式位于８０４ｃｍ－１，这和８１０ｃｍ－１附近没有拉曼和红外谱线的实验结果不符。在８００～１０００ｃｍ－１的范围内只有四个振动模式，明显少于拉曼和红外光谱在该范围内的谱线数目。所以我们认为Ｈｏｗａｒｄ模型需要进一步地完善和修正，ｐｏｌｙ（ｄＴ）·ｐｏｌｙ（ｄＡ）·ｐｏｌｙ（ｄＴ）必须具有三条不完全一致的脊骨     

Evaluation of the Complexation Process Between Poly(Aspartic Acid) and Poly(Ethylene Glycol) Through Dynamic Rheology and Electrokinetic Potential

Investigations concerning the interactions between the polymeric pair constituted of poly(aspartic acid) (PAS) as a proton-donating polycarboxilic acid and poly(ethylene glycol) (PEG) as a proton-accepting compound are continued from previous studies. The complexation between PAS and PEG has potential use as a matrix for encapsulation of bioactive substances with potential biomedical applications. The interactions that occurred were monitored in dilute solutions by determining the particle size distribution and the zeta potential (ZP) through laser light scattering method; data associated with oscillatory rheology was used as a complementary analysis. The influence of the ratio between the components and the temperature conditions during the complexation process brought additional data concerning the intermolecular links formed through hydrogen bonds.     

Discrimination of Poly(butylenes adipate-co-terephthalate) and Poly(ethylene terephthalate) with Fourier Transform Infrared Microscope and Raman Spectroscope

ABSTRACT

The analysis of plastics and fibers is of importance to forensic scientists, especially in the investigation of trace evidence. In this study, we use Fourier transform infrared microscope and confocal Raman spectroscope to investigate two kinds of polymers: poly(butylenes adipate-co-terephthalate) and poly(ethylene terephthalate), which are very similar in structure and cannot be discriminated easily with other instruments. Infrared and Raman spectra were tentatively interpreted. The indicative peaks (937 cm^?1, 1121 cm^?1 in Infrared spectra; 996 cm^?1, 1396 cm^?1 in Raman spectra) to distinguish the two polymers were also summarized. The data in this study can help forensic scientists identify these two polymers accurately and avoid wrong certificate of authenticity. The data also offer the producer and researchers an effective and fast method to characterize and identify the poly(butylenes adipate-co-terephthalate).     

Microstructure,Rheology, and Potential Oil Absorbency of Poly(Butyl Methacrylate) and Poly(Hydroxyethyl Methacrylate) Blends

To prepare oil-absorptive polymers with moderate cross-linking structure, poly(butyl methacrylate) (PBMA) was synthesized as a linear hydrophobic polymer by suspension polymerization. In addition, hydroxyethyl methacrylate (HEMA), as a monomer, which could construct a network structure among the macromolecules via hydrogen bond interactions, was solution polymerized in dimethylacetamide (DMAc) with PBMA, yielding a polymer blend of PBMA and PHEMA. The solution of the polymer blend was investigated by rotational viscometry and extended rheometry. The results showed that the viscosity varied greatly with the temperature and shear rate for three different compositions. Fourier transform infrared (FTIR) spectra indicated that an entanglement or interlocking cross-linking structure of molecular chains was constructed by hydrogen bonds. The results from nuclear magnetic resonance (NMR) spectra exhibited a downfield movement of the proton peak as influenced by end groups or hydroxyls in the polymer chains. The rheological measurements demonstrated that the cross-linking structure greatly affected the rheological behavior of the blend solution. In addition, the cross-linking structure was also evaluated by oil absorbency of films.     

High-Pressure Analysis of the Multiple Melting Endotherms of Poly(ethylene succinate) and Poly(butylene succinate)

The origin of the multiple melting peaks in two linear polyesters, poly(ethylene succinate) (PES) and poly(butylene succinate) (PBS), of isothermally crystallized samples was investigated by differential scanning calorimetry (DSC) at atmospheric pressure and high-pressure differential thermal analysis (HP-DTA) at elevated pressures. In PES, the DSC melting curves showed three endothermic peaks at slow heating rates, which decreased to two with increasing heating rates. The HP-DTA curves showed that the area (qualitative) and peak height of the high-temperature peak decreased with increasing pressure and merged with the low-temperature peak at pressures above 450 MPa. This behavior supported the melting, recrystallization, and remelting model for the observed multiple melting endotherms. In PBS, the DSC melting curves were similar to those seen in PES. The HP-DTA curves were also similar to PES up to 400 MPa, but above this pressure the area and the peak height of the high-temperature peak and the temperature difference between the high- and low-temperature peaks remained unchanged. This observation suggested that the two peaks in PBS were due to the melting of two populations of crystals with different lamellar thickness originally present in the sample. The multiple melting behavior in isothermally crystallized PBS is proposed to incorporate both the melting of two populations of crystals and melting, recrystallization, and remelting.     

Improving the Barrier Properties of Poly(Lactic Acid) by Blending with Poly(Ethylene-Co-Vinyl Alcohol)

Poly(lactic acid) (PLA)/poly(ethylene-co-vinyl alcohol) (EVOH) blends were prepared via melt blending to improve the barrier properties of PLA. The phase morphologies and final properties (rheological behavior, thermal and dynamical-mechanical features, barrier properties, and mechanical behaviors) of the blends were investigated as a function of the EVOH content. The results indicated that hydroxyl groups of EVOH promoted the degradation of PLA, and thus affected the viscosities and morphologies of the resulting blends. The intrinsic viscosities of PLA in the blends decreased with the content of EVOH. The PLA and EVOH presented typical phase-separated morphologies, with a relatively small domain size of the EVOH phase. The EVOH enhanced the cold-crystallization behavior of PLA. The barrier properties to water vapor and oxygen increased linearly with increasing EVOH content.     

Miscibility and Isothermal Crystallization Behavior of Poly (Butylene Succinate-co-Adipate) (PBSA)/Poly (Trimethylene Carbonate) (PTMC) Blends

Poly(butylene succinate-co-adipate) (PBSA)/poly (trimethylene carbonate) (PTMC) blend samples with different weight ratios were prepared by solution blending. The morphologies after isothermal crystallization and in the melt were observed by optical microscopy (OM). Differential scanning calorimetry (DSC) was used to characterize the isothermal crystallization kinetics and melting behaviors. According to the OM image before and after melting, it was found that the blends formed heterogenous morphologies. When the PTMC content was low (20%), PBSA formed the continuous phase, while when the PTMC contents was high (40%), PBSA formed the dispersed phase. The glass transition temperatures (T_g) of the blends were determined by DSC and the differences of the T_g values were smaller than the difference between those of pure PBSA and PTMC. In addition, the equilibrium melting points were depressed in the blends. According to these results, the PBSA/PTMC blends were determined as being partially miscible blends. The crystallization kinetics was investigated according to the Avrami equation. It was found that the incorporation of PTMC did not change the crystallization mechanism of PBSA. However, the crystallization rate decreased with the increase of PTMC contents. The change of crystallization kinetics is related with the existences of amorphous PTMC, the partial miscibility between PLLA and PTMC, and the changes of phase structures.     

Molecular Simulations of Physical and Chemical Properties of Poly(Imino Ketone)s

Six kinds of poly(imino ketone)s (PIKs) with different structures were designed, involving different ratios of carbonyl and imino groups, and the insertion of two types of bulky groups in the main chain. Under 3D periodic boundary conditions, simulations of physical and chemical properties for PIKs with six different structures on the molecular level, including fractional free volume (FFV) and melt density, solubility, and glass transition temperature, were carried out.     

离子液体凝胶聚合物电解质PP13TFSI-LiTFSI-P(VdF-HFP)的电化学性能 (cited: 1)

采用溶液浇铸法将N-甲基-N-丙基哌啶二(三氟甲基磺)亚胺(PP13TFSI)、二(三氟甲基磺)亚胺锂与偏氟乙烯-六氟丙烯共聚物(P(VdF-HFP))混合制备离子液体凝胶聚合物电解质(ILGPEs). 通过扫描电子显微镜观察发现,这种离子液体凝胶聚合物电解质由于液体相的均匀分布而具有疏松的结构. 采用电化学阻抗、计时电流法、线性扫描伏安法测试了电解质的离子电导率、锂离子迁移数和电化学窗口. 室温下离子液体凝胶聚合物电解质的离子电导率和锂离子迁移数分别是0.79 mS/cm和0.71,电化学窗口为0～5.1 Vvs. Li⁺/Li. 电池性能测试表明,这种离子液体凝胶聚合物电解质在Li/LiFePO₄电池中是稳定的,放电容量在30、75和150mA/g倍率下分别为135、117和100 mAh/g,电池经100个循环后容量保持在100%而几乎没有衰减.