Intercomponent Reactions Research Articles

New strategy to increase oil biodegradation efficiency by selecting isolates with diverse functionality and no antagonistic interactions for bacterial consortia

The degradative ability of ten bacterial isolates individually as well as in three constructed consortia were evaluated at in-vitro and the soil environments. The bacterial consortia comprising A: five Pseudomonas, two Bacillus, one Chryseobacterium, one Ochrobactrum, and one uncultured bacterium; B: three Pseudomonas, one Bacillus, and one Chryseobacterium; C: two Pseudomonas, one Bacillus, one Ochrobactrum, and one uncultured bacterium were constructed based on degradation capacity and functional diversity. The ranking in terms of the removal effectiveness of consortia was B>A>C, in in-vitro and the soil environments. The B consortium degraded 51.6%, 61.8%, and 56.7% of the crude oil and its aliphatic and aromatic fractions, respectively. Furthermore, the B consortium represented a higher removal efficiency by 28% in the soil environment than the control. Analyses of the residual oil showed different alkane chains (≤C15 and >C25) were completely degraded (100%) in B treatment. Hence, functional diversity led to the degradation of a larger amount as well as a broader range of crude oil aliphatic and aromatic hydrocarbons. The measured interactions between isolates revealed adverse relationships between consortia components not only in in vitro but also in the soil environments. Two isolates (Ochrobactrum, and uncultured strain) had growth interference and inhibitory effects on the other components which led to a significant decline in removal efficiency in both environments. The indication was that besides the functional diversity, inter-component reactions appear to be an influential principle in the performance of microbial consortia.

Mesoporous silica with block copolymer templates: Modulation of porosity via block copolymer reaction with silica

A polystyrene-block-poly(2-hydroxyethylacrylate) diblock copolymer (PS-b-PHEA) was synthesized via a reversible addition-fragmentation chain transfer (RAFT) polymerization approach. This novel amphiphilic diblock copolymer was successfully used as the template to obtain the mesoporous silica materials. In order to modulate the porosity of mesoporous silica materials, this diblock copolymer was further functionalized via its reaction with 3-isocyanatopropyltriethoxysilane (IPTES) to afford a new diblock copolymer bearing an alkyloxysilane subchain. This derivate diblock copolymer was also employed to prepare the mesoporous silica materials through the inter-component reaction between the block copolymer and silica matrix. The results of small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) measurements showed that the inter-component reaction can be utilized to modulate the morphologies and porosity of the mesoporous silica materials.

Epoxy resin containing polyphenylsilsesquioxane: Preparation, morphology, and thermomechanical properties

AbstractPolyphenylsilsesquioxane (PPSQ) was incorporated into an epoxy resin to prepare organic–inorganic composites, and two strategies were adopted to afford composites with different morphologies. Phase separation induced by polymerization occurred in the physical blending system. However, nanostructured composites were obtained when a catalytic amount of aluminum triacetylacetonate was added to mediate the reaction between PPSQ and diglycidyl ether of bisphenol A (DGEBA). The intercomponent reaction significantly suppressed the phase separation on the micrometer scale. Organic–inorganic composites with different morphologies displayed quite different thermomechanical properties. Both differential scanning calorimetry and dynamic mechanical analysis showed that the nanostructured composites possessed higher glass‐transition temperatures than the phase‐separated composites with the same loading of PPSQ, although the intercomponent reaction between PPSQ and DGEBA reduced the crosslinking density of the epoxy matrix. This result was ascribed to the presence of nanosized PPSQ domains in the nanostructured composites, which acted as physical crosslinking sites and thus reinforced the epoxy networks. The nanoreinforcement of the PPSQ domains afforded the enhanced dynamic storage modulus for the nanostructured composites in comparison with the phase‐separated composites with a PPSQ concentration less than 15 wt %. In terms of thermogravimetric analysis, the organic–inorganic composites displayed improved thermal stability and flame retardancy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1093–1105, 2006

Inorganic–organic nanocomposites of polybenzoxazine with octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane

AbstractOcta(propylglycidyl ether) polyhedral oligomeric silsesquioxane (OpePOSS) was used to prepare the polybenzoxazine (PBA‐a) nanocomposites containing polyhedral oligomeric silsesquioxane (POSS). The crosslinking reactions involved with the formation of the organic–inorganic networks can be divided into the two types: (1) the ring‐opening polymerization of benzoxazine and (2) the subsequent reaction between the in situ formed phenolic hydroxyls of PBA‐a and the epoxide groups of OpePOSS. The morphology of the nanocomposites was investigated by means of scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Differential scanning calorimetry and dynamic mechanical analysis showed that the nanocomposites displayed higher glass‐transition temperatures than the control PBA‐a. In the glassy state, the nanocomposites containing less than 30 wt % POSS displayed an enhanced storage modulus, whereas the storage moduli of the nanocomposites containing more than 30 wt % POSS were lower than that of the control PBA‐a. The dynamic mechanical analysis results showed that all the nanocomposites exhibited enhanced storage moduli in the rubbery states, which was ascribed to the two major factors, that is, the nanoreinforcement effect of POSS cages and the additional crosslinking degree resulting from the intercomponent reactions between PBA‐a and OpePOSS. Thermogravimetric analysis indicated that the nanocomposites displayed improved thermal stability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1168–1181, 2006

Poly(hydroxyether of bisphenol A)/poly(vinyl acetate) blends:In situ polymerization preparation, morphology, and properties

The blends of poly(hydroxyether of bisphenol A) (phenoxy) and poly(vinyl acetate) (PVAc) were prepared through in situ polymerization, i.e., the melt polymerization of diglycidy ether of bisphenol A (DGEBA) and bisphenol A in the presence of PVAc. The polymerization reaction started from the initial homogeneous ternary mixture of PVAc/DGEBA/bisphenol A; the phase separation induced by reaction occurred as the polymerization proceeded. The phenoxy/PVAc blends with PVAc content up to 20 wt % were obtained and were further characterized by the solubility, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electronic microscopy (SEM). The results indicate that no intercomponent reaction occurred during the in situ polymerization. All the blends display separate glass transition temperatures (Tg's); the very fine phase-separated morphology was obtained by this polymerization blending method. Mechanical tests show that the prepared blends exhibited substantial improvement of mechanical properties, especially in impact strength, which could be ascribed to the formation of the fine phase-separation morphology during in situ polymerization. The thermogravity analysis (TGA) of the blends showed that the thermal stability of the PVAc-rich phases in the blends was enhanced in comparison to the pure PVAc due to the synergistic contribution of the two phases in energy transportation. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2329–2338, 1999

A polymer of bisphenol A and bisphenol A diglycidyl ether and its blends with poly(styrene-co-acrylonitrile):In situ polymerization preparation, morphology, and mechanical properties

The poly(hydroxy ether of bisphenol A)-based blends containing poly(acrylontrile-co-styrene) (SAN) were prepared through in situ polymerization, i.e., the melt polymerization between the diglycidy ether of bisphenol A (DGEBA) and bisphenol A in the presence of poly(acrylontrile-co-styrene) (SAN). The polymerization reaction started from the initial homogeneous ternary mixture of SAN/DGEBA/bisphenol A, and the phenoxy/SAN blends with SAN content up to 20 wt % were obtained. Both the solubility behavior and Fourier transform infrared (FTIR) spectroscopy studies demonstrate that no intercomponent reaction occurred in the reactive blend system. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electronic microscopy (SEM) were employed to characterize the phase structure of the as-polymerized blends. All the blends display the separate glass transition temperatures (Tg's); i.e., the blends were phase-separated. The morphological observation showed that all the blends exhibited well-distributed phase-separated morphology. For the blends with SAN content less than 15 wt %, very fine SAN spherical particles (1–3 μmm in diameter) were uniformly dispersed in a continuous matrix of phenoxy and the fine morphology was formed through phase separation induced by polymerization. Mechanical tests show that the blends containing 5–15 wt % SAN displayed a substantial improvement of tensile properties and Izod impact strength, which were in marked contrast to those of the materials prepared via conventional methods. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 525–532, 1999