丙烯酸甲酯和甲基丙烯酸酯基团转移无规共聚的竞聚率

丙烯酸甲酯和甲基丙烯酸酯基团转移无规共聚的竞聚率⒇邹友思林东海张景辉潘容华（厦门大学化工系，厦门大学核磁共振实验室，厦门，３６１００５）单体竞聚率作为一个定量数据，对于不同投料比下共聚物组成的预计和控制，共聚反应动力学和机理研究均有重要作用。丙烯酸...     

Preparation and magnetic properties of polymer magnetic composites based on acrylate resin filled with nickel plating graphite nanosheets

Nickel plating graphite nanosheets (Ni/GNs) were prepared by electroless plating method using graphite nanosheets (GNs). Then a novel polymer magnetic composites based on acrylate pressure-sensitive adhesive (acrylate PSA) filled with Ni/GNs were fabricated by solution blend method. The Ni/GNs and acrylate PSA/Ni/GNs composites were characterized by scanning electron microscope (SEM)/energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and transmission electron microscope (TEM). All results showed that relatively uniform and compact Ni layer is successfully coated onto GNs under the given conditions, furthermore, Ni/GNs are homogeneously dispersed in acrylate PSA. The VSM results showed that the saturation magnetization of acrylate PSA/Ni/GNs composites increases with an increasing content of Ni/GNs while the coercivity decreases with an increasing content of Ni/GNs. When the content of GNs is 20 wt%, acrylate PSA/Ni/GNs composites exhibites good mechanical properties.     

Fabrication of acrylate monolith using photopolymerization: Effect of light intensity on electrochromatographic performance

A hexyl acrylate monolith was prepared via photopolymerization into a cyclic olefin copolymer micro-device for reversed-phase electrochromatography purposes. This work deals with the influence of the irradiation conditions (irradiation time and light intensity) used during synthesis on the electrochromatographic performances of the monolithic column obtained. Up to day, the monolith structure was often controlled by means of irradiation time at constant light intensity, but the effect of light intensity (irradiance) on the monolith structure was scarcely considered. This study shows a strong effect of light intensity on electrochromatographic efficiency. Using an optimal light intensity of 4.7 mW/cm(2) and an irradiation time of a few minutes allows obtaining heights equivalent to a theoretical plate reaching down to 5 μm for the reversed-phase separation of six polycyclic aromatic hydrocarbons.     

Chiral phosphinothiourea-catalyzed asymmetric Morita-Baylis-Hillman reactions of acrylates with aromatic aldehydes

A series of chiral bifunctional phosphinothioureas were synthesized and applied to the enantioselective Morita-Baylis-Hillman reaction of aromatic aldehydes with acrylates. In the presence of 8 mol % of organocatalyst 2e, the Baylis-Hillman adducts were obtained in good enantioselectivities and up to 96% yield under mild reaction conditions.     

Study of peak shape and efficiency in butyl acrylate-based monolithic columns for capillary electrochromatography

The study and modelling peak shape of in capillary electrochromatography (CEC), obtained using butyl acrylate (BA)-based monolithic columns, is described in this article. A modified-Gaussian model, which is a function of conventional experimental parameters: retention time (t_R), peak height (H₀) and standard deviation (σ₀) at the peak maximum, and left (A) and right (B) halfwidths, was used to describe the peaks of thiourea and several polyaromatic hydrocarbons compounds, which were eluted under several applied voltages. A mean relative error below 2% in the prediction of peak shape is obtained. Based on peak parameters, an easy and reliable estimation of global chromatographic performance, efficiency and peak capacity of BA-based monoliths was also considered. A comparison in terms of chromatographic performance of BA-based monoliths in CEC with CE mode and RPLC microparticulate columns was also performed.     

Surface modification of P(EMA-co-HEA)/SiO2 nanohybrids for faster hydroxyapatite deposition in simulated body fluid?

P(EMA-co-HEA)/SiO₂ nanocomposites with 0, 15 and 30 wt% of silica were obtained by copolymerization of ethyl methacrylate, EMA, and hydroxyethyl acrylate, HEA, during the simultaneous acid-catalyzed sol–gel polymerization of tetraethoxysilane, TEOS. A surface modification treatment was applied in order to reduce the induction time for hydroxyapatite (HAp) nucleation, combining a previous NaOH attack to increase the number of surface nucleating sites, and an alternate soaking process in Ca and P solutions to form apatite precursors, prior to the immersion in a simulated body fluid (SBF). The NaOH treatment was not effective by itself in shortening the HAp induction time. It introduced sodium carboxylates in the copolymer but hydrolyzed the silica network excessively, thus reducing the surface nucleating potential of its boundary silanols. Therefore, bioactivity was only due to the surface carboxylate groups of the organic phase. Maybe a controlled dissolution extent of the silica network so as to improve bioactivity could be attained by reducing the duration of the NaOH-treatment. This would be interesting in the hybrid with 30 wt% of silica, because its dense silica network is not able to hydrolyze in SBF without any previous treatment, whereas the silica network in the hybrid with 15 wt% of silica hydrolyzes at the surface promoting the deposition of HAp. The CaP treatment was able to coat the surfaces of the samples with a calcium phosphate layer within minutes. This amorphous calcium phosphate acted as HAp precursor, skipping the induction period in SBF.     

ESTIMATION OF REACTIVITY RATIOS OF METHYL ACRYLATE WITH N-ARYLMETHACRYL-AMIDE COPOLYMERS BY ~1H NMR METHOD

The copolymerizations of methyl acrylate (MA) with different N- arylmethacrylamide (N-ArMA) were carried out in benzene solution by free radical initiation. The compositions of the copolymers were deter mined by ~1H NMR method. The monomer reactivity ratios were calculated by the Fineman-Ross (F-R) method. The reactivity ratios and the activity of various N-ArMA with MA were investigated.     

聚合物—皮革复合材料的研究：Ⅰ.丙烯酸酯单体在铬鞣猪皮中的聚合过程

采用Ｋ＿２Ｓ＿２Ｏ＿８－ＮａＨＳＯ＿３引发体系，研究了丙烯酸乙酯（ＥＡ）、甲基丙烯酸丁酯（ＢＭＡ）及其二元混合单体（ＥＡ－ＢＭＡ）在铬鞣猪皮中的聚合过程，考察了反应温度、时间、单体浓度和铬鞣猪皮的部位不同对反应的影响，初步探讨了改性过程的反应机理。     

Photochromic polymers: effects of structure and environment on photoresponsiveness

In this review paper the photoresponsiveness of photochromic macromolecules under different structural and environmental conditions is discussed with reference to results from the authors' laboratories. Polypeptides, in particular poly(L -glutamic acid) and poly(L -lysine), with spirobenzopyrane side chains show photoinduced conformational variations which are amplified by addition of organic acids or bases to hexafluoro-2-propanol (HFP) solutions. Thus combination of light and environment effects allows modulation of order–disorder conformational transitions. Such photoindiced conformational changes are not observed in the case of macromolecules with a hydrocarbon main chain and azobenzene or stilbene side chains, obtained by polymerization of acrylic monomers. However, even in these systems structural variations affect the dependence of optical properties on irradiation. Moreover, the combination of organic solvents and water shows that polymer solubility can be modulated by light.     

聚丙烯酸丁酯/蓖麻油聚氨酯半互穿弹性体网络研究

用同步预聚合法合成了聚丙烯酸丁酯/蓖麻油聚氨酯半(SEN),通过拉伸试验、TBA和SEM等手段对其性能和形态进行了表征.结果表明,在一定组分比下半SEN的力学性能协同增加.该半SEN为部份相容体系,具有两相结构,相区尺寸约8000um左右.讨论了形态对性能的影响.