This literature review covers the solubility and processability of fluoropolymer polyvinylidine fluoride (PVDF). Fluoropolymers consist of a carbon backbone chain with multiple connected C–F bonds; they are typically nonreactive and nontoxic and have good thermal stability. Their processing, recycling and reuse are rapidly becoming more important to the circular economy as fluoropolymers find widespread application in diverse sectors including construction, automotive engineering and electronics. The partially fluorinated polymer PVDF is in strong demand in all of these areas; in addition to its desirable inertness, which is typical of most fluoropolymers, it also has a high dielectric constant and can be ferroelectric in some of its crystal phases. However, processing and reusing PVDF is a challenging task, and this is partly due to its limited solubility. This review begins with a discussion on the useful properties and applications of PVDF, followed by a discussion on the known solvents and diluents of PVDF and how it can be formed into membranes. Finally, we explore the limitations of PVDF’s chemical and thermal stability, with a discussion on conditions under which it can degrade. Our aim is to provide a condensed overview that will be of use to both chemists and engineers who need to work with PVDF.
This study explores a binary solvent system composed of biobased Cyrene and its derivative Cygnet 0.0 for application in membrane technology and in biocatalytic synthesis of polyesters. Cygnet‐Cyrene blends could represent viable replacements for toxic polar aprotic solvents. The use of a 50 wt % Cygnet‐Cyrene mixture makes a practical difference in the production of flat sheet membranes by nonsolvent‐induced phase separation. New polymeric membranes from cellulose acetate, polysulfone, and polyimide are manufactured by using Cyrene, Cygnet 0.0, and their blend. The resultant membranes have different morphology when the solvent/mixture and temperature of the casting solution change. Moreover, Cyrene, Cygnet 0.0, and Cygnet‐Cyrene are also explored for substituting diphenyl ether for the biocatalytic synthesis of polyesters. The results indicate that Cygnet 0.0 is a very promising candidate for the enzymatic synthesis of high molecular weight polyesters.
With the increasing restriction and control of hazardous solvents, safer alternatives need to be identified. Here a contemporary approach to solvent selection and substitution is presented that offers a more scientific alternative to the simple "like-for-like" exchange. A new family of levoglucosenonederived compounds is proposed, modeled to determine their solvent properties, synthesized, and tested. These new molecules show promise as replacements for polar aprotic solvents that have chronic toxicity issues, such as dichloromethane, nitrobenzene, and N-methylpyrrolidinone. The success of this approach makes it possible for academia and industry to make calculated, intelligent choices for solvent substitution in the future.
Short-chain
oxymethylene dimethyl ethers (OMEs) (molecular formula:
H3CO–(CH2O)
n
–CH3, where n = 3–5) have
previously been studied as diesel-like fuels and fuel additives. OMEs
can be produced from sustainably sourced methanol, and tests indicate
that they are neither genotoxic nor mutagenic. In this report, their
potential as solvents has been investigated to expand the bio-derived
solvent space. According to traditional solvatochromic parameters,
a commercial mixture of OME3–5 and its individual
components (OME3, OME4, and OME5)
have solvation properties similar to problematic industrial ether
solvents such as 1,4-dioxane. Peroxide formation, one of the chief
dangers of classical ether solvents, was found to occur much more
slowly in OMEs than in conventional solvents such as tetrahydrofuran
(THF), demonstrating an improved safety profile. The commercial OME3–5 mixture was found to be broadly miscible with organic
solvents but immiscible with water, suggesting potential application
in aqueous extractions. It performed well in the dissolution of polystyrene
and removal of paints and coatings, indicating OME3–5 may suitable to replace dichloromethane in polymer recycling, polymer
welding, and cleaning applications. To further demonstrate applicability
as a solvent, this mixture was shown to facilitate a model Suzuki
coupling reaction at rates similar to cyclopentyl methyl ether, which
is currently marketed as a green ether. Finally, OME3–5 proved a suitable solvent for enzymatic polymerization, giving high
yields, moderately high degrees of polymerization, and remarkably
narrow dispersity values.
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