哌嗪季铵碱催化剂的合成及其在异氰酸酯聚合反应中的应用

在温和条件下合成了一种用于脂肪族异氰酸酯聚合反应的哌嗪类双季铵碱催化剂, 制备过程简单, 且催化剂具有较高的催化活性和选择性, 催化反应所生成的聚合产物中所需的三聚体成分较高, 产物色度较低.     

聚外消旋乳酸的IPDI溶液扩链

以异佛尔酮二异氰酸酯(IPD I)为扩链剂,以外消旋乳酸(D,L-LA)直接熔融聚合合成的低分子量聚外消旋乳酸(PDLLA)为预聚体,在四氢呋喃溶液中进行扩链得扩链产物Ⅰ。Ⅰ用粘均分子量(Mη),IR,1H NMR,DSC及X-射线衍射等表征。与2,4-甲苯二异氰酸酯(TD I)的扩链产物(Ⅱ)比较,Ⅰ成功地引入了NH和IPD I反应后的刚性片段,使M,ηTg,Tm,结晶度等相应提高。但由于IPD I反应活性不如TD I,故反应速率比用TD I时慢;Ⅰ分子中脂肪环的刚性不如苯环,TⅠg低于TⅡg。     

Characterization of Novel Biodegradable Segmented Polyurethanes Prepared from Amino-Acid Based Diisocyanate

Segmented polyurethanes (SPUs) which were expected to yield non-toxic degradation products were synthesized from lysine-based diisocyanate (LDI), 1,3-propanediol (PDO), and polycaprolactone diol (PCL). SPUs were synthesized via a standard two-step prepolymer method. The hard segment fraction was changed in order to tune the mechanical properties and the degradability. The aggregation structures of the SPUs were characterized by infrared spectroscopy and differential scanning calorimetry (DSC), temperature dependence of dynamic viscoelasticity, and small-angle X-ray scattering (SAXS). DSC and dynamic viscoelastic measurements revealed that the glass transition temperature (T_g) of the soft segment increased with an increase in the hard segment fraction. SAXS of SPUs revealed the aggregation states of hard and soft segments. Furthermore, the degradation of SPUs was investigated by exposing the polymers to a buffer solution at 310 K (pH=7.6). The degradation rate of SPUs increased with an increase in the soft segment fraction. This is because the soft segment has the hydrolyzable ester linkages and the ester linkages are susceptible to hydrolysis compared with the urethane linkages. Finally, an electrospray deposition method was used to fabricate biodegradable SPU micro-fibers. FE-SEM images showed that higher concentration of solution favored the formation of uniform biodegradable micro-fibers without beads-like structure.     

Heavy metal adsorption ability of a new composite material based on starch strengthened with chemically modified cellulose

Adsorption of heavy metals (Pb, Zn, and Cu) on a new bioadsorbent based on starch reinforced with modified cellulose with toluene‐diisocyanate has been studied using batch‐adsorption technology. The study was carried out in order to find if this bio material, designed for seedling pots manufacture, is able to act like a barrier between soil pollutants and plants. The influence of contact time, pH, adsorbent dose, and salt concentrations was also evaluated. The obtained data were examined using the Langmuir and Freundlich adsorption models. Optimal results were obtained at pH 5.0, temperature of 25°C, contact time of 120 minutes, and an adsorbent dose of 4 mg/mL. Experimental data along with computed Langmuir parameters show that the adsorption process is favorable, and the maximum adsorption capacity of the adsorbent for lead, zinc, and copper was 66.66, 58.82, and 47.61 mg/g, respectively.     

Kinetic Modeling from Early Product Development to Polymerization Process Optimization

Summary: This contribution illustrates how kinetic modeling supports early product development stages under industrial constraints also for smaller scale products. Diisocyanate oligomerization is selected as an example. Data for model parameterization and validation are acquired in kinetic experiments with on-line IR monitoring. Based on these measured data and a proposed reaction scheme for the cyclo-oligomerization of diisocyanates with equal reactivity of both isocyanate groups, two kinetic models differing in level of detail are developed. All experimental trends are described correctly with these kinetic models. A functional group based model is used for parameterization and prediction of conversion profiles. This model version is also applied for assessing working hypotheses on the details of the catalytic cycle and for developing strategies for catalyst and process optimization. A second model takes into account full molecular weight distribution and thus enables prediction of individual oligomer concentrations. Fast assessment of process alternatives is possible with both models.     

Isophorone‐based organometallic chromophores: Synthesis,characterization and investigation of electro‐optical properties

A series of hybrid donor–acceptor complexes with a ferrocene moiety and isophorone derivatives were synthesized. Data from ¹H NMR, ¹³C NMR, Fourier transform infrared, atomic absorption and mass spectroscopies and CHN analysis supported the predicted structure of the products. A comparative investigation was performed using UV–visible, cyclic voltammetry and fluorescence measurements. Density functional theory was used to optimize the chromophore structure and calculation of highest occupied and lowest unoccupied molecular orbital energy levels. The ferrocene/isophorone hybrids show useful properties for further development and studies as electro‐optic materials.     

Synthesis,characterization, and electroluminescence of polyfluorene copolymers containing T‐shaped isophorone derivatives

We have successfully synthesized a series of new fluorene‐based copolymers, poly[(9,9‐bis(4‐octyloxy‐phenyl)fluorene‐2,7‐diyl)‐co‐[2(3{2[4(2{4[bis(bromophenyl‐4yl) amino]phenyl}vinyl)‐2,5‐bisoctyloxyphenyl]vinyl}‐5,5‐dimethyl‐cyclohex‐2‐enylidene)malononitrile] (PFTBMs), with varying molar ratios of the low‐energy band gap comonomer, 2(3{2[4(2{4[bis(4‐bromophenyl)amino]phenyl}vinyl)‐2,5‐bisoctyloxyphenyl]vinyl}‐5,5‐dimethyl‐cyclohex‐2‐enylidene)malononitrile (BTBM). To prepare BTBM (which has a T‐shaped structure) from triphenylamine, dialkoxy phenyl, and isophorone, we introduced three individual segments of an isophorone derivative containing two cyanide groups at the carbonyl position, a dialkoxy phenyl group for increased solubility, and a triphenyl amine for effective charge transfer. Furthermore, we introduced vinyl linkages between each segment to increase the length of π‐conjugation. The synthesized polyfluorene copolymers with the BTBM, PFTBMs, were synthesized via palladium‐catalyzed Suzuki coupling reactions. The photoluminescence emission spectra of the synthesized polymers in solution did not show significant energy transfer from PBOPF segments to the BTBM units. Light‐emitting devices based on these polymers were fabricated with an indium tin oxide/poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/polymers/Balq/LiF/Al configuration. Examination of the electroluminescence emission of the synthesized polymers showed that the maximum wavelength shifted continuously toward long wavelengths with as the number of BTBM units in the polymer main chain was increased. In particular, a device using PFTBM 05 exhibited a maximum brightness of 510 cd/m² and a maximum current efficiency of 0.57 cd/A. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 82–90, 2010     

Biodegradable aliphatic thermoplastic polyurethane based on poly(ε‐caprolactone) and L‐lysine diisocyanate

A biodegradable aliphatic thermoplastic polyurethane based on L ‐lysine diisocyanate and 1,4‐butanediol hard block segments, and 2000 g/mol poly(ε‐caprolactone) diol soft block segments was synthesized. The resulting polymer was a tough thermoplastic with ultimate tensile strength of 33 MPa and elongation of 1000%. The polymer displayed classic segmented thermoplastic elastomer morphology with distinct hard block and soft block phases. Thermal and dynamic mechanical analyses determined that the material has a useful service temperature range of around ?40 °C to +40 °C, making it an excellent candidate for low‐temperature elastomer and film applications, and potentially as a material for use in temporary orthopedic implant devices. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2990–3000, 2006     

Influence of surface polymeric oxide species on the product distribution in the aromatization of isophorone on alumina supported vanadia and molybdena catalysts

Polymeric oxide species possessing high Brönsted acidity formed on V₂O₅/Al₂O₃ and MoO₃/Al₂O₃ are found to be responsible for the transformation of isophorone to isoxylitones. Improved selectivity to 3,5-xylenol, with the addition of K₂O as promoter substantiates this observation.CT Communication No. 3077     

Influence of Accelerated Weathering on the Properties of Polypropylene/Polylactic Acid/Eucalyptus Wood Composites

In the view of producing environmentally friendly materials without compromising properties, new composites containing polypropylene as a matrix and eucalyptus wood, with or without 15% of polylactic acid, were melt processed. In order to improve compatibility between components, a chemical modification of wood with toluene-2,4-diisocyanate (TDI) was realized and evidenced by changes in FT-IR and XPS spectra. The morphological, mechanical, and thermal characterizations of the obtained composites were evaluated before and after accelerating weathering. The results showed that the material comprising 15% TDI-modified wood, PP, and 15% PLA exhibited the best properties.