新型聚丙烯酸酯类柴油降凝剂分子模型的建立及验证

在前期工作得出的正构烷烃含量与浊点、冷滤点、凝点的定量关系模型基础上，选择柴油降凝剂的基团对柴油降凝剂分子结构进行了设计，得出了设计模型。结果表明，将含氮基团引入柴油降凝剂可以显著提高柴油降凝剂的性能。根据设计模型合成了一系列聚丙烯酸单酯和混合酯柴油降凝剂，并通过对柴油降凝剂的性能测试结果和自行设计的计算程序对设计模型进行了验证，结果表明，从柴油正构烷烃含量对柴油降凝剂的配比进行设计是可行的。     

Linear silver clusters in aqueous solution (clusterites): radiation-induced chemical synthesis and properties

The formation and properties of the products of the radiation-induced chemical reduction of silver ions in aqueous solutions containing sodium polyacrylate were investigated. The absorption spectra of these species exhibit a band at 290 mn and a band in the visible region. The latter shifts from 470 nm to -800 nm with time or after the addition of silver ions. The species obtained (clusterites) arc linear silver clusters bound to the carboxyl groups of the ion exchanger. The red shift of the visible band is due to the increase in their size. The mechanism of the formation and the structure of the clusterites are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1429–1435, June, 1996.     

Preparation and characterization of polytetrafluoroethylene‐polyacrylate core–shell nanoparticles

Polytetrafluoroethylene (PTFE)‐polyacrylate core–shell nanoparticles were produced by using PTFE micropowder and acrylate via seeded emulsion polymerization in the presence of fluorosurfactant. The properties of emulsion under various polymerization conditions were investigated and optimized. The chemical composition of the PTFE‐polyacrylate nanoparticles was characterized by Fourier‐transform infrared spectrometry (FTIR). The particle size and core–shell structure of the resulting PTFE‐polyacrylate nanoparticles were confirmed by transmission electron microscopy (TEM). Wettability of the PTFE‐polyacrylate core–shell particles was higher than the pristine PTFE. The formation of this kind of PTFE‐polyacrylate core–shell nanoparticles could improve the compatibility of PTFE with other materials because PTFE is covered by polyacrylate shell, which make them promising in various fields. Copyright © 2007 John Wiley & Sons, Ltd.     

Nanocrystalline cellulose/fluorinated polyacrylate latex via RAFT‐mediated surfactant‐free emulsion polymerization and its application as waterborne textile finishing agent

A simple method for nanocrystalline cellulose (NCC)/fluorinated polyacrylate was developed by RAFT‐mediated surfactant‐free emulsion polymerization, in which the nanocomposites formed a core‐shell spherical morphology. The influence of the content of NCC‐g‐(PAA‐b‐PHFBA) (AA was acrylic acid, HFBA was hexafluorobutyl acrylate) on the properties of latex and film were systematically studied. The monomer conversion, the tensile strength, and water–oil repellency of film increased first and then decreased, the latex particle size decreased first and then decreased, when the content of NCC‐g‐(PAA‐b‐PHFBA) increased from 1 to 6 wt %. Elongation at break and thermal stability distinctly decreased when the content of NCC‐g‐(PAA‐b‐PHFBA) gradually increased. XPS showed that the fluorine‐containing groups well concentrated at the film–air interfaces during the annealing process. SEM analysis revealed that the treated fiber had a rugged surface, and the treated fabric had an excellent water repellency. In addition, this green grafting method in water offered a new perspective for the fabrication of exceptional NCC‐based nanocomposites with NCC as the core and also helped to promote the potential applicability of NCC in a range of multipurpose applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1305–1314     

The Effect of Weight Fraction of H-PDMS on the Latex Membrane and the Stability of Composite Emulsion of H-PDMS/Acrylate

High hydrogen-containing polymethylsiloxane(H-PDMS)/polyacrylate composite emulsion was synthesized by a drop-adding method for monomer emulsion. The effects of weight fraction of H-PDMS on the stability of composite emulsion, water resistance and heat-aging resistance of the latex membrane have been investigated. The TEM demonstrated that latex particles are a core-shell structure. By analyzing the spectrums of FTIR and ¹H-NMR, it can be indicated that H-PDMS had reacted with acrylate monomer resulting chemical bond formation. The core-shell structure and chemical bond play an important role to restrain phase separation of composite emulsion and enhance the stability of the emulsion. By analyzing the surface tension, apparent viscosity and morphological structure, the results showed that the stable composite emulsion system can be obtained in which the average latex particle size was smaller than 90 nm when weight fraction of H-PDMS is below 16% (based on the weight of acrylate monomer), the stable emulsion system can be obtained in which the average latex particle size becomes larger than 90 nm when the weight fraction of H-PDMS is above 20% of the acrylate monomer. The DSC demonstrated that the T_g of pure polyacrylate is 49°C, and there is only one T_g (35°C) when the weight fraction of H-PDMS is 13%, but there are two T_g (15°C and 25°C) when the weight fraction of H-PDMS is 16%. In addition, the water resistance and heat-aging resistance of composite latex membrane enhanced gradually with the increase of amount of H-PDMS.     

New chiral liquid crystal monomers and cholesteric polyacrylates: synthesis and characterisation

The synthesis of new chiral monomers (M₁ ?M₃ ) based on menthol and the corresponding polyacrylates (P₁ ?P₃ ) is described. The chemical structures, formula and phase behaviour of the obtained monomers and polymers were characterised with FT-IR, ¹H-NMR, elemental analyses, differential scanning calorimetry (DSC), polarising optical microscopy (POM) and X-ray diffraction (XRD). The effect of the mesogenic core rigidity, spacer length and menthyl steric effect on the phase behaviour of M₁ ?M₃ and P₁ ?P₃ is discussed. The expected mesophase of the compounds based on menthol can be obtained by inserting a flexible spacer between the mesogenic core and the terminal groups. For the chiral monomers and polyacrylates, their corresponding melting temperature (T _m), glass transition temperature (T _g) and clearing temperature (T _i) increased with an increase of the mesogenic core rigidity; while the T _m, T _g and T _i decreased with increasing the spacer length. M₁ and P₁ showed no mesophase, while M₂ and M₃ all revealed a SmC* and cholesteric phases. P₂ and P₃ only showed a cholesteric phase.     

Dynamic mechanical behavior of a side-chain liquid crystalline polyacrylate

The phenomenology of the α- and β-relaxation processes in an amorphous and a crystallized specimen of a side-chain LC polyacrylate, based on the azobenzene mesogenic unit, was investigated by thermal and dynamic mechanical methods. The activation energy of the β relaxation of the crystallized sample is equal to that of the amorphous sample. The α-transition process of the amorphous sample was described by the WLF equation. In contrast, the α-relaxation behavior of the amorphous part of the semicrystalline sample was described by a double Arrhenius law broken at T = T_g. This peculiar behavior has been tentatively related to the decrease of the motion characteristic length of the macromolecules confined in the multidomain structure of the semicrystalline state. © 1996 John Wiley & Sons, Inc.     

聚丙烯酸钠吸收释放氮肥性能

研究了聚丙烯酸钠(PAANa)吸液率及其对氮肥的吸收释放性能。结果表明,尿素对PAANa吸液率没有影响,氯化铵使其吸液率大大降低,且浓度越大吸液率越小;PAANa对不同浓度尿素溶液的吸液率均为370 g/g,对质量浓度为5、10、15和20 g/L氯化铵溶液的吸液率分别为82、62、56和55 g/g。在尿素溶液中,分配系数(mkd)约为1,而在氯化铵溶液中,mkd>1,随着氯化铵浓度增大mkd减小;PAANa对尿素没有富集作用,对NH4 有富集作用;但PAANa对尿素的吸收容量约为NH4 的10倍。PAANa对吸收的尿素和NH4 均具有缓慢释放性能,在水中经4次浸泡(24 h/次),尿素和NH4 累积释放率分别在80%和60%左右;FT-IR分析表明,NH4 与树脂中阳离子发生了离子交换。     

聚丙烯酸修饰咔唑的电化学聚合及表征

合成了侧链带有咔唑的N-丙烯酰氧己基咔唑(MACZ),通过自由基聚合得到聚N-丙烯酰氧己基咔唑(PMACZ),在四氢呋喃含10%三氟化硼乙醚与四氟化硼四丁基胺的混合电解质溶液中,直接阳极氧化PMACZ获得自支撑交联网状的聚(聚N-丙烯酰氧己基咔唑)(PPMACZ)薄膜.PPMACZ薄膜具有良好的氧化还原性和热稳定性,电导率为1.34×10-5S·cm-1.1HNMR和红外光谱表明PMACZ二次聚合反应发生在咔唑单元的3,6位上,荧光光谱表明PPMACZ薄膜是一种良好的蓝色发光材料.     

Liquid-Crystalline Solvents as Mechanistic Probes. 10. Dynamics of Intramolecular Quenching of Pyrenyl Fluorescence in the Liquid-Crystalline and Isotropic Phases of a Cholesteric Solvent1

Abstract

The effect of cholesteric order in a 59.5/15.6/24.9 (w/w/w) mixture of cholesteryl oleate/cholesteryl nonanoate/cholesteryl chloride (CM) on the intramolecular fluorescence quenching of l,3-bis(l-pyrenyl) propane (P3P) has been explored. A comparison with fluorescence quenching of N,N-dimethyl-4-[3-(l-pyrenyl)propyl]aniline (P3D) in CM is made. From the Arrhenius activation parameters for quenching in the cholesteric and isotropic phases, it is concluded that the motions which take the ground state conformers of P3P to their quenching transition state are nearly impervious to macroscopic CM mesophase order: in the cholesteric phase, E'_a = 10.5±0.4 kcal mol^?1 and ΔS^? = 1 ± 1 eu; in the isotropic phase, E'_a = 10.0 ± 0.2 kcal mol^?1 and ΔS^? = 0 ± 0.5 eu. An explanation of these results is advanced.