Comparative analysis of shape memory-based self-healing coatings

Self-healing materials exhibit the ability to repair and to recover their functionality upon damage. Here, we report on an investigation into preparation and characterization of shape memory assisted self-healing coatings. We built on past work in which poly(ε-caprolactone) electrospun fibers were infiltrated with a shape memory epoxy matrix and delve into fabricating and characterizing a coating with the same materials, but employing a blending approach, polymerization induced phase separation. After applying controlled damage, the ability of both coatings to self-heal upon heating was investigated. In both methods, coatings showed excellent thermally induced crack closure and protection against corrosion, with the blend approach being more suitable for large-scale applications given its process simplicity. Two different approaches to the preparation of shape memory-based self-healing coatings were compared for their ability to heal structurally and functionally by heating. These two approaches, electrospinning versus polymerization-induced phase separation were found to feature comparable and quite complete healing, with the latter system offering the advantage of facile processing. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1415–1426     

Sustainable,mild and efficient p-methoxybenzyl ether deprotections utilizing catalytic DDQ

A procedure for the selective deprotection of p-methoxybenzyl ethers using catalytic amounts of DDQ and of sodium nitrite, with oxygen as the terminal oxidant, is reported.     

Total synthesis of amorfrutin A via a palladium-catalyzed migratory prenylation–aromatization sequence

The total synthesis of amorfrutin A, a prenyl bibenzyl natural product has been achieved in five steps from 2,2,6-trimethyl-4H-1,3-dioxin-4-one. The key step of the synthesis is an efficient palladium(0)-catalyzed decarboxylative prenylation migration and aromatization sequence.     

Batch versus Flow Photochemistry: A Revealing Comparison of Yield and Productivity

The use of flow photochemistry and its apparent superiority over batch has been reported by a number of groups in recent years. To rigorously determine whether flow does indeed have an advantage over batch, a broad range of synthetic photochemical transformations were optimized in both reactor modes and their yields and productivities compared. Surprisingly, yields were essentially identical in all comparative cases. Even more revealing was the observation that the productivity of flow reactors varied very little to that of their batch counterparts when the key reaction parameters were matched. Those with a single layer of fluorinated ethylene propylene (FEP) had an average productivity 20 % lower than that of batch, whereas three‐layer reactors were 20 % more productive. Finally, the utility of flow chemistry was demonstrated in the scale‐up of the ring‐opening reaction of a potentially explosive [1.1.1] propellane with butane‐2,3‐dione.     

The synthesis and X-ray structure of five co-ordinate imidodiphosphinate complexes of indium(III)

We report the synthesis and structural characterisation of three five co-ordinate indium(III) bis-chelate complexes of imidodiphosphinates with general formula InCl{N(PR₂X)₂}₂, (R=Ph or Prⁱ, X=S or Se), formed from the 1:2 reaction of indium(III) trichloride and the potassium or sodium salt of the ligand in methanol/THF. The complexes consist of discrete monomeric, molecules and show a trigonal–bipyramidal co-ordination pattern. These are the first examples of five co-ordinate complexes containing this type of ligand, in contrast to other indium(III) and main group element complexes of similar ligands in which only the six co-ordinate tris-chelates are known.