Fabrication,chemical modification,and topographical patterning of reactive gels assembled from azlactone‐functionalized polymers and a diamine

The work reported here demonstrates an approach to the fabrication of chemically reactive and topographically patterned hydrogels using the azlactone‐functionalized polymer poly(2‐vinyl‐4,4'‐dimethylazlactone) (PVDMA) and the hydrophilic diamine Jeffamine®. Gels were initially assembled in DMSO but can be subsequently transferred into aqueous media to form hydrogels. Spectroscopic characterization of assembled gels demonstrated that variation in the stoichiometric ratio of azlactones to amines during gel synthesis permits control over the extent of crosslinking in the gels. Residual azlactones not consumed during crosslinking can be exploited to further functionalize these gels with hydrophobic, hydrophilic, and macromolecular amines that influence the physicochemical properties of these materials in aqueous solvents. The surface and bulk of these gels can be differentially functionalized (i.e., different functional groups on the gel surface relative to the bulk) by taking advantage of different rates of diffusion of macromolecular amines versus small molecule amines into assembled gels. Finally, these azlactone‐functionalized gels can be topographically patterned with microwell arrays using a replica molding technique and chemically modified postfabrication with amine nucleophiles. This reactive approach to the fabrication of topographically patterned and chemically functionalized hydrogels offers a straightforward method for the rapid synthesis of micropatterned scaffolds of interest in a broad range of applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3185–3194     

Calorimetric measurements of diluted spin crossover complexes [FexM1−x(btr)2(NCS)2]·H2O with M = Zn and Ni

Motivated by the application of the First Order Reversal Curve (FORC) technique to obtain a distribution of like spin domains in the spin crossover complexes [Fe_xM_1−x(btr)₂(NCS)₂]·H₂O with M^II = Zn and Ni, we have performed Differential Scanning Calorimetry (DSC) experiments. We have measured the heat capacity in the heating and cooling modes and then calculated the enthalpy and the entropy variations at the phase transition. In the framework of an Ising-like model, we have converted the experimental thermal hysteresis into terms of physical parameters related to these compounds. We have also performed a statistical analysis of these parameters and concluded that the correlation between them increases with the dilution degree of these spin crossover complexes.     

Proposal for underwater structural analysis using the techniques of ESPI and digital holography

The purpose of this article is to study the application of the holographic interferometry techniques in the structural analysis of submarine environment. These techniques are widely used today, with applications in many areas. Nevertheless, its application in submarine environments presents some challenges. The application of two techniques, electronic speckle pattern interferometry (ESPI) and digital holography, comparison of advantages and disadvantages of each of them is presented. A brief study is done on the influence of water properties and the optical effects due to suspended particles as well as possible solutions to minimize these problems.     

Synthesis of a Chiral Hexane-1,6-Dinitrile from D-Glucose

Abstract

Using well-established methodology, D-glucose was transformed into a tribenzoyloxy cyclohexanone oxime derivative. Sodium azide treatment permitted the regiospecific exchange of the benzoyloxy group at a α-position relative to ketone oxime. Under standard Beckmann conditions the α-azido was oxime cleaved to provide an ω-dicyano compound.