Mixture Flash Point Calculation: Recent Advances and a Closer Look at Biodiesel

To safely handle, transport, and store flammable or combustible liquids, such as biodiesel and its blends, it is important to have knowledge of a few physical-chemical properties. The Flash Point is an important one, as it is related to the flammability of the fuel blend. It can be experimentally measured through open cup or closed cup standard procedures. However, due to the usual scarcity of experimental data for multicomponent systems, developing a model to predict flash points of mixtures is of interest. To do so, there are a few possible approaches, which include empirical regression of data, vapor pressure-based methods, and QSPR. When it comes to mixtures, the most popular modeling method is based on vapor pressure, which usually employs LeChatelier’s rule and vapor–liquid equilibria (VLE) calculations to flash point prediction. Generally, a γ–φ approach is adopted to describe the VLE behavior, although some authors have shown interest in φ–φ approaches. In recent years, studies on QSPR for FP prediction of mixtures have evolved, which represents an advance toward more generalized FP prediction models. Additionally, COSMO type models have been gaining attention in FP prediction, usually associated with vapor pressure models or even empirical models. When it comes to biodiesel though, not much progress has been made since 2014, with just a few works being published since then. This paper seeks to review advances made in FP prediction methods for mixtures in general, while giving attention to those involving biodiesel and petro-diesel

Microfluidic Fabrication of Pluronic Vesicles with Controlled Permeability

Block copolymers with a low hydrophilic-to-lipophilic balance form membranes that are highly permeable to hydrophilic molecules. Polymersomes with this type of membrane enable the controllable release of molecules without membrane rupture. However, these polymersomes are difficult to assemble because of their low hydrophobicity. Here, we report a microfluidic approach to the production of these polymersomes using double-emulsion drops with ultrathin shells as templates. The small thickness of the middle oil phase enables the attraction of the hydrophobic blocks of the polymers adsorbed at each of the oil/water interfaces of the double emulsions; this results in the dewetting of the oil from the surface of the innermost water drops of the double emulsions and the ultimate formation of the polymersome. This approach to polymersome fabrication enables control of the vesicle size and results in the efficient encapsulation of hydrophilic ingredients that can be released through the polymer membrane without membrane rupture. We apply our approach to the fabrication of Pluronic L121 vesicles and characterize the permeability of their membranes. Furthermore, we show that membrane permeability can be tuned by blending different Pluronic polymers. Our work thus describes a route to producing Pluronic vesicles that are useful for the controlled release of hydrophilic ingredients