用烯酸合成聚烯酸酯的合理路线——由一道高考试题引发的思考

用烯酸合成聚烯酸酯，一是先酯化后加聚，二是先加聚后酯化，哪一条合成路线更合理？2016年北京高考卷化学部分25题第（7）问设计烯酸酯合成路线，学生感到困惑，提出质疑，促使教师研究该类素材在高考命题中的应用，解决问题、答疑解惑，从而促进教师和学生换位思考，教学相长。

聚氨酯／聚丙烯酸酯复合涂料的新进展

本文综述了近年来聚氨酯／聚丙烯酸酯复合涂料的新进展，主要介绍了合成方法、特点及几类新型的涂料体系，并对该领域进一步的发展提出了看法。

Incorporation of Reactive Corrosion Inhibitor in Waterborne Acrylic Polyurethane Coatings and Evaluation of its Corrosion Performance

Hydroxyl-epoxy phosphate （HEP） as a reactive corrosion inhibitor was innovatively synthe- sized by the reaction of bisphenol A epoxy resin with phosphoric acid. HEP was mixed with hydroxyl acrylate resin, and crosslinked with waterborne isocyanate curing agent, which was used to form waterborne HEP/acrylic polyurethane composite （HEP-APU） coatings on Q235 steel surfaces. Electrochemical impedance spectroscopy and polarization curves were applied to analyze the corrosion behavior of the HEP-APU coatings in 3.5wt% NaCl solutions. The results indicated that the HEP-APU coatings show a superior passivation property and efficient corrosion protection of Q235 steel. The waterborne acrylic polyurethane coating containing 0.5wt% HEP exhibited the best corrosion performance among all the coating specimens. The improved flash-rust resistance can be attributed to the introduction of the phosphate group which could form phosphate film on the steel substrate.

Preparation of Hollow Silica Microspheres via Poly（N-isopropylacrylamide）

Core-shell structured SiO2/poly（N-isopropylacrylamide） （SiO2/PNIPAM） microspheres were successfully fabricated through hydrolysis and condensation reaction of tertraethyl orthosilicate （TEOS） on the surface of PNIPAM template at 50 ~C. The PNIPAM template can be easily removed by water at room temperature so that SiO2 hollow microspheres were finally obtained. The transmission electron microscope and scanning electron microscope observations indicated that SiO2 hollow microspheres with an average diameter of 150 nm can be formed only if there are enough concentration of PNIPAM and TEOS, and the hy- drolysis time of TEOS. FTIR analysis showed that part of PNIPAM remained on the wall of SiO2 because of the strong interaction between PNIPAM and silica. This work provides a clean and efficient way to prepare hollow microspheres.

Post treatment preparation of hybrid metal halide perovskite nanocrystal-embedded polymethylmethacrylate blends with enhanced stablity

Hybrid organic-inorganic perovskites have been the subject of recent intense interest due to advances in photovoltaic and other optoelectronic applications. However, their poor stability limits commercial market application We enhance water stability by post treatment preparation of hybrid metal halide perovskite nanocrystal-embedded polymethylmethacrylate （PM- MA） blend films. Through blending process without any cleaning of nanocrystals, crystalline hybrid organic-inorganic perovs-kite nanocrystals were incorporated into PMMA matrix with well-dispersion Passivation of PMMA on the surface of the per-ovskite nanocrystals results in decreased traps and a long photoluminescence （PL） lifetime despite the bromine vacancies in the crystal lattice. Moreover, such color purity and inherent high transmittance for fluorescence emission of perovskite nanocrystals will endow the films with promising potentials in diverse practice photonic applications.

STUDY ON THE STARCH GRAFTED ACRYLATE MONOMERS AND ITS COMPATIBILITY FOR THE BLEND SYSTEM OF STARCH AND POLYETHYLENE

By means of initiation of the high temperature and shearing stress of an extruder,we synthesized the graft copolymer of starch with acrylate monomers based on the simple dry method.The effects of reaction conditions on graft copolymerization were discussed. Grafted starch used as a compatibilizer for the blend system of starch and polyethylene was further investigated. The results indicate that grafted starch as a compatibilizer can improve the mechanical properties and rheologic properties of the blend of starch and polyethylene.

Preparation and Characterization of Two-component Waterborne Polyurethane Comprised of Water-soluble Acrylic Resin and HDI Biuret

A two-component waterborne polyurethane(2K-WPU) was prepared by mixing water-soluble acrylic resin and hexamethylene diisocyanate biuret, and then diluted for phase inversion with water. Compared with water-soluble acrylic resin, the phase inversion of 2K-WPU occurs at lower water content. It is indicated by TEM that 2K-WPU parti-cles show a core-shell structure, in which HDI biuret is encapsulated by hydrophilic acrylic resin. 2K-WPU emulsion with HDI biuret has larger particle size and narrower distribution index, while for 2K-WPU emulsion with HDI iso-cyanurate, the latex not only has large particle size, but also has two-peak distribution. FTIR shows that the reaction be-tween HDI biuret and acrylic resin can complete in 12h. In addition, studies on effect of composition of acrylic resin on performance of 2K-WPU show that narrowing the polar difference between water-soluble acrylic resin and HDI biuret and improving the miscibility of two components are the key to prepare the transparent and high gloss films with high crosslinking density.

Separation of aluminosilicates and diaspore from diasporic-bauxite by selective flocculation

The flocculation tests of four pure minerals(diaspore,kaolinite,illite,pyrophyllite)and bauxite ore were investigated by the sedimentation.The dispersion behavior of the four pure minerals shows a very good consistency with the variation of zeta potential.The concentrate with the mass ratio of Al2O3 to SiO2(m(Al2O3)/m(SiO2))8.90 and the recovery of Al2O3 86.98%is obtained from bauxite ore(m(Al2O3)/m(SiO2)=5.68)in pH range of 9.5-10.0 by using sodium carbonate(5 kg/t)and sodium polyacrylate(7 g/t)as dispersant and flocculant respectively.Sodium carbonate acts as both pH modifier and favorable dispersant for aluminosilicates.The high performance of sodium polyacrylate on flocculation for diaspore is contributed to the carboxyl of sodium polyacrylate that interacts with active Al sites on diaspore by chemical absorption,and the hydrogen bond effects between hydroxyl group of macromolecule and surface Al—OH on diaspore to accelerate the sedimentation of diaspore.

Synthesis and Characterization of Poly(St-co-BA) Latex with an Organic-Inorganic Hybrid Compound as Emulsifier

A poly (St-co-BA) latex was successfully synthesized by using an organic-inorganic hybrid compound (OIHC), an aliphatic carboxylate sodium/nano-silica composite, as the emulsifier, and investigated by particle size analyzer, transmission electron microscope (TEM), optical contact angle measurement (OCA) and dynamic mechanical analyzer (DMA). It was found that the protective agent, sodium polyacrylate (PA),could obviously improve the polymerization stability and the functional monomer, glycidyl methacrylate (GMA), could enhance the store stability of the latex. The particle size of poly(St-co-BA) latex decreased and then leveled off as OIHC content increased. TEM shows that the prepared polymers were actually organic-inorganic nanocomposites, and these films have better waterproof property than those prepared by traditional poly(St-co-BA) latex or organic silicone modified poly(St-co-BA) latex. The nanocomposite polymer has much higher glass transition temperature than organic silicone modified poly(St-co-BA) polymer containing the same organic silicone content.

Synthesis and properties of UV curable polyurethane acrylates based on two different hydroxyethyl acrylates

Two kinds of UV curable polyurethane acrylate oligomers （PUPA and PUCA） were synthesized via the addition reaction between isophorone diisocyanate （IPDI） and polyethylene glycol monoacrylate （PEA6） or polycaprolactone modified hydroxyethyl acrylate （PCLA2）. The structures of PUPA and PUCA were characterized by Fourier transform infrared spectroscopy （FT-IR）, IH nuclear magnetic resonance （^H NMR）, gel permeation chromatography （GPC） and differential scanning calorimeter （DSC）, and the thermal stability and dynamic mechanical thermal properties of their cured films were measured by thermogravimetric analysis （TGA） and dynamic mechanical analysis （DMA）, respectively. The viscosity of the oligomers and mechanical properties of the cured films were also studied. The results show that both oligomers have narrow molecular weight distribution. The viscosity of PUPA is 2.310 Pa.s at 25 ℃, while that of PUCA is： up to 3.980 Pa-s. The UV cured PUPA and PUCA films have homogeneous phase structure, and the PUCA film shows higher glass transition temperature and storage modulus. Furthermore, the PUCA film possesses better mechanical properties than PUPA, while the latter shows better alkali resistance.

Preparation of poly （methyl methacrylate）／nanometer calcium carbonate composite by in-situ emulsion polymerization

Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.

Polycarbonate/Polypropylene/Fibrillar Silicate Ternary Nanocomposites via Two-step Blending Process: Degradation and Morphology

The method of two-step melt blending was used to prepare polycarbonate/polypropylene/attapulgite ternary nanocomposite, and the various techniques including gel permeation chromatography, rheometer, transmis- sion electron microscope, dynamic mechanical analysis were used to examine the degradation of polycarbonate (PC) and the nanocomposite morphology. The results showed that the molecular weight degradation of PC triggered by attapulgite (AT) during the direct blending process was inhibited effectively by using two-step melt blending, in which AT was blended with polypropylene (PP) prior to compound with PC. The morphology of encapsulation was formed in the PC matrix, where PP encapsulates AT fibrillar single crystals to form a core-shell inclusion. Dynamic mechanical analysis (DMA) measurements showed that the PC/PP/AT ternary nanocomposites were more effective than conventional PC/PP blends in reinforcement, meanwhile the addition of AT in the ternary nanocomposites shifted the glass transition temperature of the PP phase to a higher value.

Spherical Micro-lens Array of PMMA Produced by Micro-molding

Micro-lens （ML） and Micro-lens array （MLA） are important optical components widely used in many fields; Soft-lithography, a vital little process technology, has its unique performance to produce ML and MLA; The cylinder and spherical MLA of polymethyl methacrylate （PMMA） were successfully obtained by micromolding inSoft-lithography. Some suitable experimental parameters in the process were discussed, and the imaging property of the MLA was also studied simply.

Study on PVA Membranes Blended with Acrylic Ester-Acrylic Acid Copolymer for Dehydration of Ethanol

The viability of polyvinyl acetate (PVA) membranes blended with acrylic ester-co-acrylic acid copolymers (AE-co-AA), for ethanol dehydration was examined. The effects of the operating temperature on the permeate flux and separation factor of the membranes were investigated. The pervaporation separation characteristics of PVA/(AE-co-AA) membranes were related to the blend ratio, the dose of crosslinking agents and the operating temperature.

UV-curing of hyperbranched polyurethane acrylate-polyurethane diacrylate/SiO_2 dispersion and TGA/FTIR study of cured films

UV-curable hyperbranched polyurethane acrylate-polyurethane diacrylate/SiO2 dispersion （HBPUA-PUDA/SiO2） was prepared with isophorone diisocyanate （IPDI）, hyperbranched polyester Boltorn H20 （H20）, hydroxy-ethyl acrylate （HEA）, polyethyleneglycol （PEG-200）and nano-SiO2. The UV curing kinetics of the films was investigated by FTIR. The results show that the curing speed of the films increases with the adding of nano-SiO2 and decreases with the adding of PUDA due to the slower chain movement. The thermal stability of the HBPUA-PUDA/SiO2 films was studied by using thermogravimetric analysis coupled with Fourier transform infrared spectroscopy （TGA/FTIR）. The results show that all films exhibit two degradation stages located at about 320 and 440℃ corresponding to the degradation for hard segments of urethane-acrylate and the degradation for soft segment and polyester core. In addition, the results from the analysis of TGA/FTIR also indicate that the decomposition temperature of HBPUA-PUDA/SiO2 film is 15℃ higher than that obtained for pure polymer. The degradation mechanism was proposed according to TGA/FTIR results.

Modified graphite filled natural rubber composites with good thermal conductivity

The rubber composites with good thermal conductivity contribute to heat dissipation of tires. Graphite filled natural rubber composites were developed in this study to provide good thermal conductivity. Graphite was coated with polyacrylate polymerized by monomers including methyl methacrylate, n-butyl acrylate and acrylic acid. The ratios between a filler and acrylate polymerization emulsion and those between monomers were varied. Eight types of surface modification formulas were experimentally investigated. Modification formula can affect coating results and composite properties greatly. The best coating type was achieved by a ratio of1:1 between methyl methacrylate and n-butyl acrylate. The coating of graphite was thermally stable in a running tire. Filled with modified graphite, the tire thermal conductivity reached up to 0.517–0.569 W·m-1·K-1. In addition, the mechanical performance was improved with increased crosslink density, extended scorch time and short vulcanization time.

Optical Properties of Nd^3＋ in Nd（DBM）3Phen-doped Poly（methyl methacrylate）

Nd（DBM）3Phen-doped （DBM is dibenzoylmethane and Phen is phenanthroline） polymethyl methacrylate （PMMA） is prepared. Optical absorption, excitation and emission spectra were analyzed for Nd^3＋ in Nd（DBM）3Phen-doped PMMA. Using the Judd-Ofelt theory, the absorption spectrum was analyzed. The Judd-Ofelt（J-O） intensity parameters of Nd（DBM）3Phen-doped polymethyl methacrylate were calculated to be Ω2 = 20.97 × 10^-20 cm^2, Ω4= 3.42 × 10^-20 cm^2, Ω6 = 2.90 × 10^-20 cm^2. The radiative lifetime （631 μs） of the excited 4F3/2 level is given. The stimulated emission cross-sections and the fluorescence branch ratios for the ^4F3/2 →^4Ij′ transitions are also evaluated. Analysis reveals that Nd（DBM）3Phen-doped PMMA is promising for application in polymer optical fibers and planar waveguides.

Preparation and Characterization of Hybrid Aqueous Dispersions Composed of Silica Sol and Poly(styrene-co-acrylate)

A stable silica sol with 3-5 nm in diameter, which can form homogeneous film without crack, was prepared and characterized. Then, the inorganic-organic hybrid aqueous dispersion composed of such a silica sol and an emulsion of styrene （St） and acrylate （Ac） copolymer was prepared and the hybrid effect between the silica sol and poly（St-co-Ac） was observed by Fourier transform infra-red （FT-IR） spectroscope. The toughness of the film prepared by this kind of hybrid aqueous dispersion was excellent, as it was enhanced appreciably by commixing with a small amount of poly（St-co-Ac） emulsion. Some amino-polysiloxane modified hybrid aqueous dispersions were also prepared and the properties of the modified dispersions and their films were investigated. The experimental results showed that the film prepared with such an amino-polysiloxane modified hybrid dispersion exhibited excellent hydrophobicity and low surface energy after heat treatment for 1.5 h, during which the formation of the graft copolymer was observed. The surface energy of this film decreases as a result of the enrichment of siloxane segments on the film surface.

Injection molding of micro patterned PMMA plate

A plastic plate with surface micro features was injection molded to investigate the effect of pressure rise of melt on the replication of the micro structures. Prism pattern, which is used in many optical applications, was selected as a model pattern. The prism pattern is 50 μm in pitch and 108° in the vertical angle. The overall size of the plate was 335 minx213 mm and the thickness of the plate varied linearly from 2.6 mm to 0.7 ram. The prism pattern was firstly machined on the nickel plated core block using micro diamond tool and this machined pattern core was installed in a mold for injection molding of prism patterned plate. Polymethyl methacrylate （PMMA） was used as a molding material. The pressure and temperature of the melt in the cavity were measured at different positions in the cavity and the replication of the pattern was also measured at the same positions. The results show that the pressure or temperature profile through the process depends on the shape and the size of the plate. The replication is affected by the temperature and pressure profiles at the early stage of filling, which is right after the melt reaches the position to be measured.

ADSORBENTS USED IN THE CLEARANCE OF ENDOTOXIN

A series of modified poly (methyl methacrylate, PMMA) resins were prepared and compared their adsorption abilities to endotoxin. The results showed that adsorbents, which were grafted with tertiary amine and long spacing arms, had the best adsorption capacities and good blood compatibility. It is hopeful to be used as adsorbent in hemoperfusion for clinical clearance of endotoxin. The influence of original concentration of endotoxin on adsorption and the adsorption mechanism were also investigated.