Two sets of waterborne polyurethane dispersions were synthesised from polycarbonate polyol with molecular mass of 500 Da and hexamethylene diisocyanate or isophorone diisocyanate. Formulations were prepared without a chain extender, with aliphatic diol with two to five carbon atoms or with diethylene glycol. Coatings were prepared on cellulose triacetate sheets, damaged by a steel-wool scratch instrument and left to heal at room temperature and at 60˚C. Self-healing efficiency was examined by comparison of haze before damage and at intervals after damage. Samples were analysed using Differential Scanning Calorimetry, Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy. The tests were repeated after 12 weeks to investigate ageing of the polymers. Samples were also tested for their stability to weathering. Optimally designed coatings obtained up to 100% recovery within 10 minutes at 60˚C and partial recovery at room temperature. The self-healing properties of coatings were found to be linked to macro-organisation of polymer chains caused by interactions between hard segments and soft segments of the polyurethane moiety, leading to phase-mixing, promoted by bulky, non-symmetrical isophorone diisocyanate, or phase-separation, promoted by linear, symmetrical hexamethylene diisocyanate. The length of chain extender was found to have large influence on formulations prepared with hexamethylene diisocyanate, increasing phase-separation and haze with the increase of chain length. Diethylene glycol was found to improve phase-mixing and self-healing properties of hexamethylene diisocyanate based materials. The influence of chain extenders was found to be minimal for isophorone diisocyanate based materials.

Irradiation sterilization of polymeric pharmaceutical processing systems and medical devices, an essential healthcare technology, is facing critical business continuity challenges, driving the need to qualify equivalent alternative irradiation technologies, such as X‐ray. Whereas the underlying there is a paucity of cross‐industry published data evaluating X‐ray irradiation effects on plastics as compared to gamma irradiation. That leads to regulatory uncertainty in the levels of costly validation data regulators will require and overall apprehension in the rate of X‐ray irradiation adoption. The present study evaluates the impact of X‐ray versus gamma irradiation on a wide range of polymers with more than 36 single‐use (SU) components, using a comprehensive set of industry aligned methods for characterization of bioprocess polymers. Whereas many of these techniques readily demonstrate changes in polymer properties following irradiation, all of the polymers evaluated demonstrated that the impact of X‐ray irradiation was to the same degree or less as compared to gamma. Increased publication of studies evaluating the impact to polymers of X‐ray versus gamma irradiation is critical to leveraging extensive, existing validation packages on bioprocess systems and medical devices obtained following gamma irradiation, and essential in qualifying X‐ray irradiation as an equivalent technology (i.e., materials are impacted to the same extent or less than gamma) that can overcome business continuity challenges to ensure continued availability of critical patient therapies.

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