Cooling a solution of a crystalline polyolefin from 1408C to room temperature causes the dissolved polymer to crystallize. If a laser beam passes through this solution, the crystallization will cause the beam to scatter, which thereby decreases the intensity of the beam. With this principle, it is possible to follow the crystallization of polyolefins under controlled cooling. An instrument capable of doing these analyses was manufactured, and several different polyolefins were analyzed. The effect of the experimental parameters are illustrated for both cooling and reheating experiments. In addition, an interesting dependence on molecular weight was also observed for a series of metallocene polypropylenes.

For the first time, the solution crystallization and dissolution behavior of polyolefins in a variety of solvents was investigated by using a recently developed crystallization based analysis technique, solution crystallization analysis by laser light scattering (SCALLS). SCALLS results provide clear evidence that crystallization and dissolution of linear polyethylene (PE) and isotactic polypropylene (iPP) are greatly influenced by the type of solvent used. It was demonstrated for a blend of PE and iPP that cocrystallization effects are minimal in solvents such as TCB and o-DCB and are significantly more pronounced in xylene and decalin. Surprisingly, in xylene, individual dissolution curves (bimodal SCALLS profile) for both PE and iPP with minimal codissolution effects were observed while in TCB, o-DCB, and decalin both components dissolve simultaneously. These findings provide a novel and facile approach to understand the effect of solvents on cocrystallization and codissolution of chemically dissimilar components in preparative fractionations such as prep TREF (which normally uses xylene), by using TCB as the crystallization solvent and xylene as the eluent.

Solution crystallization analysis by laser light scattering offers a direct way of studying the solution crystallization of polyolefins. The technique yields similar results to Crystaf, but in a shorter time and with apparently greater sensitivity in some cases. The use of SCALLS is demonstrated for the study of selected propylene/ higher a-olefin copolymers. Some conclusions are also drawn regarding the effect of molecular weight on the solution crystallization of polyolefins.

Beneficial soil microbes like plant growth-promoting rhizobacteria (PGPR) significantly contribute to plant growth and development through various mechanisms activated by plant-PGPR interactions. However, decoding this belowground chemical intercommunication is still enigmatic, thus hindering the use of PGPR formulations for sustainable agriculture. Therefore, we report the application of mass spectrometry (MS)-based untargeted metabolomics and molecular networking (MN) to interrogate and profile the intracellular chemical space of PGPR Bacillus strains: B. laterosporus, B. amyloliquefaciens, B. licheniformis 1001 and B. licheniformis M017 and their consortium. The results revealed differential and diverse chemistries in the four Bacillus strains when grown separately, and also differing from when grown as a consortium. MolNetEnhancer networks revealed 11 differential molecular families that are comprised of lipids and lipid-like molecules, benzenoids, nucleotide-like, and organic acids and derivatives. Consortium and B. amyloliquefaciens were characterized by the high abundance of surfactins, whereas B. licheniformis strains were characterized by the unique presence of lichenysins. Thus, this work demonstrates that the application of metabolome mining tools offers unique opportunities to map the microbial chemical space, thus providing unprecedented access and insights to molecular information of microbial systems. Such fundamental knowledge is essential for the informed future formulation of PGPR-based biostimulants.

In this study, multidetector Thermal FFF (ThF3) is utilized to study amphiphilic block copolymers in different selective and nonselective solvents. Depending on the solvent quality and the polymer concentration, amphiphilic block copolymers can form aggregates or micelles; the blocks can adopt different coil conformations. ThF3 is chosen because of the noninvasive nature of the technique that will not destroy the conformations that amphiphilic block copolymers can adopt in selected solvents. The effect of different polymer-solvent systems on the diffusion and thermal diffusion coeffi cients, and the resultant separation, is studied. It is found that, depending on the solvent, the macromolecules adopt extended coil or partially collapsed coil conformations. Experimental conditions are identifi ed where the block copolymers behave similar to one of their parent homopolymers. For the fi rst time, it has been shown that ThF3 is a unique tool to study the solution properties and the coil conformations of amphiphilic copolymers and to relate this information to the fractionation behavior of the polymers. block copolymers have a tendency to aggregate and even form micelles under suitable conditions. Classical chromatographic techniques utilize packed columns to fractionate polymers. These packed columns contained microporous particles as stationary phase that can destroy given conformations or prevent aggregation or micelle formation. To study the behavior of amphiphilic block copolymers in different solvents, fi eld-fl ow fractionation (FFF), specifi cally thermal fi eld-fl ow fractionation (ThF3) was chosen. ThF3 utilizes an open channel that is conducive to the analysis of shear sensitive polymer structures. The mechanism of separation is not reliant on adsorption and thus sample loss is minimized. The separation force, a thermal gradient, is applied perpendicular to the eluent fl ow through the channel and the separation is governed by both diffusion and thermal diffusion. These two forces act in opposition to each other and allow separation according to molecular size and chemical composition.ThF3 and, more recently, microthermal field-flow fractionation are subtechniques of FFF that have been