The design of polymeric biomaterials with long‐lasting X‐ray contrast could advance safe and effective implants and contrast agents. Herein, a new set of wholly aliphatic, iodinated polyesters are synthesized and evaluated as high‐contrast biomaterials and nanoparticle contrast agents for general computed tomography imaging. A single iodinated monomer is used to synthesize a variety of aliphatic polyesters with tunable thermal and mechanical properties. These iodinated polyesters are end‐functionalized with a photocurable methacrylate group, which allows easy processability. The resulting materials exhibit no cytotoxicity and are radiopaque, containing over 40% iodine by weight after processing. The polymers can be formulated into lipid–polymer hybrid nanoparticles using a modified nanoprecipitation method. Initial studies indicate that these nanoparticles show good continual contrast over 60 minutes with no uptake into the kidneys. The work presented here illustrates a novel platform for iodinated polyesters that exhibit high radiopacity and processability, low cost, and no cytotoxicity. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2171–2177

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We report the first supramolecular engineering polymer with melt viscosity suitable for non-degradative processing plus enhanced thermal and mechanical properties.

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In order to better understand the design rules of epoxy–phenol thermosets we will report on the chemistry and (thermo)mechanical properties of cured epoxy–phenol thermoset films. Ortho‐, meta‐ and para‐isomers of dihydroxybenzene (DHB) were reacted with the diglycidyl ether of bisphenol A (DGEBA) in the presence of an acid catalyst or triphenylphosphine (PPh3). The glass transition temperatures (Tg) of the cross‐linked films decreases in the order of meta‐ (Tg = 115°C) > ortho‐ (Tg = 102°C) > para‐DHB (Tg = 96°C) as measured by differential scanning calorimetry. Uniaxial tensile testing of cross‐linked films showed excellent stress–strain behavior. The average ultimate strength values ranged from 65 to 82 MPa and the average values of the strain‐at‐break ranged from 4.8% to 6.9% at 25°C for all cross‐linked films. When a PPh3 was used, the network properties were profoundly different. The base catalyzed thermoset of DGEBA and meta‐DHB shows a Tg of 85°C, which is 30°C lower than the Tg of the acid‐catalyzed analog. Tensile films appear to be more ductile, as they exhibit a strain‐at‐break of 20%. The results of this study confirm that simple dihydroxybenzene hardeners can be used to prepare cross‐linked films with excellent thermomechanical properties.

This study uses confocal microscopy and image processing to investigate the microstructural changes of coating–metal systems immersed in a heated acidic bath. Unlike standard optical microscopy techniques, 3D confocal microscopy images can quantitatively reveal microscopic defects formed at early stages of cathodic delamination. The coatings are made of fluorescent epoxy–phenolic resins cured at high temperatures onto tinplate (T23) and tin-free steel (TFS) substrates. When the coated metal substrates are immersed in acetic acid, a series of microscopic corrosion events occur at the polymer–metal interface. These events are quantified by changes in the thickness distribution of the degraded samples relative to that of intact coatings. The degradation rate is highest for epoxy–phenolic polymers on TFS substrates, represented by multiple orders of magnitude increase in the number density of defect sites. Higher molecular weight coatings provide slightly better resistance against delamination. The coating thickness dictates the rate of oxygen diffusion and ion transport along the polymer–coating interface, where raised asperities serve as localized sites for metal oxidation and formation of alkaline species, leading to subsequent delamination of the cured polymers from the surfaces. The results show that the metal surface topology is as important as chemistry when designing the corrosion resistance of products containing acidic liquids, and that confocal microscopy is useful in quality control through early detection of mesoscale polymer failure.

We seek to reveal the corrosion protection mechanisms of intact thermosetting epoxy coatings on metal substrates as a prerequisite for the future design of innocuous alternatives to bisphenol A-based epoxy...

We have explored the structure–property relationships of a series epoxy–methylolphenol based thermoset films. Ortho‐, meta‐, and para‐isomers of methylolphenol, that is, ortho‐methylolphenol, meta‐methylolphenol and para‐methylolphenol, respectively, were reacted with the diglycidyl ether of bisphenol A (DGEBA) in the presence of an acid catalyst (CYCAT® XK 406 N). Thermogravimetric analyses showed that irrespective of the methylolphenol structure used, all crosslinked films exhibit 5% weight loss at 343–360°C under nitrogen. The glass transition temperature (Tg) decreases in the order of ortho‐ (Tg = 117°C) > para‐ (Tg = 102°C) > meta‐methylolphenol (Tg = 82°C) as measured by differential scanning calorimetry. Uniaxial tensile testing of thin films shows good stress–strain behavior, with ultimate tensile strength values of 75 MPa and 6% strain‐at‐break. Homo‐crosslinking of methylolphenol moieties can occur under the reaction conditions used but in the presence of DGEBA, the methylolphenols prefer to undergo epoxy ring‐opening reactions. This was confirmed by the uniform networks that were formed, that is, no block‐formation was observed. The results of this study confirm that simple methylolphenol hardeners can be used to prepare crosslinked epoxy‐based films with excellent thermomechanical properties.