Ternary blends from biological poly(3-hydroxybutyrate-co-4-hydroxyvalerate), poly(L-lactic acid), and poly(vinyl acetate) with balanced properties.

Herein, poly(3-hydroxybutyrate-co-4-hydroxyvalerate) (P34HB), poly (L-lactic acid) (PLA), and poly(vinyl acetate) (PVAc) were initially melt compounded to prepare a ternary blend with balanced properties. Further, the miscibility, phase morphology, thermal and crystallization behaviors, and rheological and mechanical properties of the blends were studied. The dynamic mechanical analysis (DMA) results indicated that P34HB and PLA were partially miscible; however, PVAc showed full miscibility with PLA and P34HB. PVAc would selectively disperse in the PLA phase when considering low content, whereas it would gradually diffuse into the P34HB phase with the increasing PVAc concentration. A phase-separated morphology was observed for all the blends using scanning electron microscopy (SEM), and the diameters of the dispersed phases increased with the increasing PVAc concentration. The crystallization of P34HB was enhanced by the presence of PLA alone and was restrained by the simultaneous incorporation of PVAc and PLA. The rheological properties of P34HB were significantly improved because of the PVAc phase. Unexpectedly, the toughness and stiffness of the P34HB in ternary blends clearly improved because of the incorporation of PLA and PVAc.

Effect of loadings of nanocellulose on the significantly improved crystallization and mechanical properties of biodegradable poly(ε-caprolactone).

Biodegradable poly(ε-caprolactone) (PCL)/nanocellulose (NC) nanocomposites were prepared using solvent-free melt processing techniques with various NC contents. Both the nonisothermal and isothermal melt crystallization processes of PCL/NC nanocomposites were significantly accelerated by adding NC. The nonisothermal melt crystallization peak temperature obviously increased from 18.8 °C for neat PCL to 30.9 °C for the PCL/NC nanocomposite with 10 wt% NC content at a cooling rate of 10 °C min-1; moreover, the half-time isothermal crystallization at 40 °C significantly decreased from 12.2 min for neat PCL to 2.0 min. Apparently, NC enhanced PCL's crystallization rate. The crystalline morphology study confirmed the increased nucleation density of PCL spherulites, indicating the role of NC as an efficient nucleating agent. Moreover, the loading of NC did not change the crystal structure of PCL, and with increase in NC content, the Young's modulus and yield strength increased; however, the elongation-at-break and the breaking strength decreased. Compared with pure PCL, the thermomechanical properties of PCL/NC nanocomposites were significantly improved. These biodegradable PCL/NC nanocomposites showed excellent crystallization capabilities and tailored mechanical properties, thus proving their potential as a substitute for traditional commercial plastics.

Morphological, thermal, rheological and mechanical properties of poly (butylene carbonate) reinforced by stereocomplex polylactide.

Fully biodegradable blends of poly (butylene carbonate) (PBC) and a bioresource-based stereocomplex polylactide (sc-PLA) were prepared by melt compounding at a temperature far below the melting point (Tm) of sc-PLA, and above the Tm of PBC, poly (l-lactide) (PLLA) and poly(d-lactide) (PDLA). sc-PLA was uniformly dispersed in the PBC matrix as spherical particles. Interestingly, the size of the dispersed sc-PLA particles did not increase significantly with increasing amounts of PLLA and PDLA. sc-PLA accelerated the non-isothermal and isothermal melt crystallization of PBC. Simultaneously, the thermal decomposition temperature of the PBC/sc-PLA blends increased by about 46 °C. The solid filler sc-PLA could reinforce the PBC matrix over a relatively wide temperature range. Consequently, formation of the percolation network structure of spherical sc-PLA in the blends significantly improved the rheological and mechanical properties of PBC after incorporation of sc-PLA. This report may open a new avenue to achieve higher-performance biodegradable polymer blend materials.

Enhancement of the properties of biosourced poly(3-hydroxybutyrate-co-4-hydroxybutyrate) by the incorporation of natural orotic acid.

The aim of this study is to use natural orotic acid (OA) as a sustainable, environmentally friendly additive to improve the crystallization, rheological, thermal, mechanical, and biodegradation properties of bacterially synthesized poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB). OA was found to be an efficient nucleating agent for P34HB, and dramatically enhanced both non-isothermal and isothermal crystallization rates. The incorporation of OA increased nucleation density and decreased spherulite size, but had little effect on the crystalline structure. The rheological properties of the P34HB were greatly improved by the solid filler OA, particularly when a percolation network structure was formed in the blends. The thermal stability of P34HB was strongly enhanced, as exemplified by the ~23 °C increase in the onset thermal decomposition temperature (To) for the blend loaded with 5 wt% OA compared to that of pure P34HB. Moreover, the yield strength and elongation at break of P34HB containing 0.5 wt% OA increased by 25% and 119%, respectively. The most intriguing result was the clear enhancement in the enzymatic hydrolysis rates of the P34HB/OA blends compared to that of neat P34HB. The synergetic improvement in these properties may be of significant importance for the wider practical application of biosourced P34HB.

Uniaxial stretching and properties of fully biodegradable poly(lactic acid)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) blends.

In this work, fully biodegradable poly (lactic acid) (PLA)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) blends of various compositions were uniaxially stretched at different stretch ratios above the glass transition temperature (Tg) of PLA. These stretched blends exhibited a closed microvoid structure, as evaluated by scanning electron microscopy. Differential scanning calorimetry and wide-angle X-ray diffraction analyses verified that stretching-induced crystallization in the α-form could be achieved in the PLA matrix. This hierarchical structure could improve the multifunctional performance of PLA blends. The density of drawn blends with a P(3HB-co-4HB) content of 30 wt% and stretch ratio of 6 was reduced by 20% as compared to neat PLA. The excellent combination of strength, modulus, and ductility of drawn blends with a P(3HB-co-4HB) content of 10 wt% and stretch ratio of 6 was demonstrated; compared to neat PLA, these parameters increased by 300%, 320%, and 317%, respectively in breaking strength, modulus, and elongation at break (172.2 MPa, 4200 MPa, and 18.4%), respectively. Meanwhile, control over the degradation rate and thermomechanical-property improvement was achieved by adjusting the stretch ratio and/or blend composition. In practical terms, this processing technique provides a new way to manufacture lightweight and high-performance microvoid-containing biopolymers.

High-performance biodegradable polylactide composites fabricated using a novel plasticizer and functionalized eggshell powder.

A novel polyester poly(diethylene glycol succinate) (PDEGS) was synthesized and evaluated as a plasticizer for polylactide (PLA) in this study. Meanwhile, an effective sustainable filler, functionalized eggshell powder (FES) with a surface layer of calcium phenyphosphonate was also prepared. Then, PLA biocomposites were prepared from FES and PDEGS using a facile melt blending process. The addition of 15 wt% PDEGS as plasticizer showed good miscibility with PLA macromolecules and increased the chain mobility of PLA. The crystallization kinetics of PLA composites revealed that the highly effective nucleating FES significantly improved the crystallization ability of PLA at both of non-isothermal and isothermal conditions. In addition, the effective plasticizer and well-dispersed FES increased the elongation at break from 6% of pure PLA to over 200% for all of the plasticized PLA composites. These biodegradable PLA biocomposites, coupled with excellent crystallization ability and tunable mechanical properties, demonstrate their potential as alternatives to traditional commodity plastics.

Polycaprolactone nanocomposite reinforced by bioresource starch-based nanoparticles.

Biodegradable polymer nanocomposites with bioresource starch-based nanoparticles (SNPs) as reinforcing fillers for polycaprolactone (PCL) were prepared by melt blending. Scanning electron microscopy observation revealed that SNPs as spherical particles were evenly dispersed in the PCL matrix without any aggregation even with the content of SNPs increasing to 10wt% in the nanocomposite. Consequently, the rheological performances of PCL have been improved efficaciously after incorporation with SNPs as well as mechanical properties, especially with a percolation network structure of SNPs in the PCL matrix formed. In addition, the enzymatic hydrolysis experiments showed a more interesting behavior that the hydrolysis rates had been accelerated apparently in the nanocomposites than that in the neat PCL as observed. Such high performance nanocomposites may have great potential in expanding the utilization of starch from sustainable resources and the practical application of PCL-based biodegradable materials.

Highly selective Pt/ordered mesoporous TiO2-SiO2 catalysts for hydrogenation of cinnamaldehyde: The promoting role of Ti(2.).

A highly selective and stable catalyst based on Pt nanoparticles confined in Mesoporous TiO2-SiO2 frameworks were prepared and employed for selective hydrogenation of cinnamaldehyde to cinnamyl alcohol. The as-prepared Pt/MesoTiO2-SiO2-M catalyst displayed excellent selectivity to cinnamyl alcohol (around 91%) at nearly complete conversion. Ti(2+) and stronger metal-support interaction (SMSI) played key roles on the adsorption behavior of cinnamaldehyde and activation of CO bonds. The existence of amorphous SiO2 and mixed TiO2 phases (anatase and rutile) was helpful for the formation of Ti(2+) sites and SMSI. The electron-enriched Pt surfaces and the formed Pt-TiOx system benefited the enhanced activity and selectivity.

Photocatalytic reduction of o-chloronitrobenzene under visible light irradiation over CdS quantum dot sensitized TiO2.

The photocatalytic activity of CdS/P25 hybrid catalysts was studied under visible-light irradiation. The CdS quantum dots sensitized P25 (CdS QDs-P25) showed extremely enhanced activity in the reduction of o-chloronitrobenzene (o-CNB) by comparing to CdS-P25 prepared by the direct deposition-precipitation method in the presence of HCOOH. The synergistic effects between CdS QDs and P25 were beneficial for the separation of photogenerated carriers in space and thus the combination of photoelectrons and holes was prevented, and the CdS QDs could provide more photocharges than CdS due to the particle size effect. Furthermore, the process of photocatalytic reduction in the present system was investigated, under visible-light irradiation, the photogenerated electrons transferred from the valence band (VB) to the conduction band (CB) of CdS QDs, and injected into the CB of inactivated P25. Meanwhile, the holes generated in the VB of CdS QDs could oxidize HCOO(-) to give ˙CO2(-) and H(+). Then, o-CNB was reduced to o-chloroaniline (o-CAN) by the couple of e(-) and ˙CO2(-) with H(+). It is a significant method and a green process for hydrogenation of nitro compounds, which may have great potential applications in the reduction of various organic chemicals.

Trace amounts of water-induced distinct growth behaviors of NiO nanostructures on graphene in CO2-expanded ethanol and their applications in lithium-ion batteries.

In this work, we have developed a new method to grow NiO nanomaterials on the surface of graphene nanosheets (GNSs). The morphologies of NiO nanomaterials grown on GNSs could be tailored by trace amounts of water introduced into the mixed solvents of CO2-expanded ethanol (CE). Small and uniform Ni-salt nanoparticles (Ni-salt-NPs) were grown on the surface of graphene oxide (GO) through the decomposition of nickel nitrate directly in CE. However, when trace amounts of water were introduced into the mixed solvents, Ni-salt nanoflakes arrays (Ni-salt-NFAs) were grown on the surface of GO with almost perpendicular direction. After thermal treatment in N2 atmosphere, these Ni-salt @GO composites were converted to NiO@GNSs composites. The forming mechanisms of the NiO-NPs@GNSs and NiO-NFAs@GNSs were discussed by series comparative experiments. The presence of the trace amounts of water affected the chemical composition and structure of the precursors formed in CE and the growth behaviors on the surface of GNSs. When used as anode materials for lithium-ion batteries, the NiO-NPs@GNSs composite exhibited better cycle and rate performance compared with the NiO-NFAs@GNSs.

Fabrication of Co(OH)2 coated Pt nanoparticles as an efficient catalyst for chemoselective hydrogenation of halonitrobenzenes.

Co(OH)(2) coated platinum nanoparticles Pt/Co(OH)(2) were prepared by microwave assistance and hydrothermal method, and the prepared samples were composed of Pt nanoparticles with an average size of 1.8 nm coated uniformly in the thin Co(OH)(2) leaves based on the results of X-ray diffraction, transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The Pt/Co(OH)(2) presented excellent catalytic performance in the chemoselective hydrogenation of halonitrobenzenes such as chloronitrobenzenes, bromonitrobenzene and iodonitrobenzene, and above 99.6% selectivity to haloanilines was achieved at complete conversion irrespective of the substrates used, even for iodonitrobenzene to which the dehalogenation is more easily to occur. Co(OH)(2) was confirmed to prohibit the dehalogenation effectively, and the Pt/Co(OH)(2) catalyst could be recycled for several times.

Polyureas from diamines and carbon dioxide: synthesis, structures and properties.

Polyureas were synthesized from diamines and carbon dioxide in the absence of any catalyst or solvent, analogous to the synthesis of urea from condensation of ammonia with carbon dioxide. The method used carbon dioxide as a carbonyl source to substitute highly toxic isocyanates for the synthesis of polyureas. FTIR and DFT calculations confirmed that strong bidentate hydrogen bonds were formed between urea motifs, and XRD patterns showed that the PUas were highly crystalline and formed a network structure through hydrogen bonds, which served as physical cross-links. The long chain PUas presented a microphase separated morphology as characterized by SAXS and showed a high melting temperature above 200 °C. The PUas showed high resistance to solvents and excellent thermal stability, which benefitted from their special network structures. The PUas synthesized by this method are a new kind of functional material and could serve some areas where their analogues with similar functional groups could not be applied.

Steaming multiwalled carbon nanotubes via acid vapour for controllable nanoengineering and the fabrication of carbon nanoflutes.

A new concept of steaming multiwalled carbon nanotubes (MWCNTs) via acid vapour was presented for controllable nanoengineering of the MWCNTs. This method is more simple, effective, precisely-controllable and environmentally-friendly compared to traditional ones. Moreover, novel porous carbon nanotubes, named carbon nanoflutes, were fabricated based on this strategy.