A series of polymers containing the 2-isopropenyl-2-oxazoline (iPOx) monomer have been synthesized by either anionic polymerization or RAFT polymerization. Both homopolymers of varying molecular weight were prepared as well as copolymers with methyl methacrylate (MMA) and N-isopropylmethacrylamide (NIPMAM) comonomers. The iPOx homopolymers were shown to be very poor Structure II tetrahydrofuran hydrate crystal growth inhibitors, indicating weak interaction of the oxazoline group with the hydrate crystal surface. They were also tested for their performance as kinetic hydrate inhibitors on a Structure-II-forming natural gas mixture. The homopolymers showed significant and increasing performance as the molecular weight decreased to 2000 Da. Copolymerization of iPOx with MMA did not improve the KHI performance, but copolymers of iPOx with NIPMAM did show an improvement, although not as good performance as polyNIPMAM homopolymer of similar molecular weight. However, using a 35:20 molar ratio iPOx:NIPMAM copolymer it is possible to obtain good KHI performance and a high cloud point of 70 °C in water, which is useful for injection into hot fluids. These results demonstrate that polymers containing predominantly non-amide-based monomers such as iPOx can be useful, high cloud point KHIs. In the case of iPOx polymers the primary inhibition mechanism appears to be nucleation inhibition since hydrate crystal growth inhibition is poor.

Biodegradable elastomers are a popular choice for tissue engineering scaffolds, particularly in mechanically challenging settings (e.g. the skin). As the optimal rate of scaffold degradation depends on the tissue type to be regenerated, next-generation scaffolds must demonstrate tuneable degradation patterns. Previous investigations mainly focussed on the integration of more or less hydrolysable components to modulate degradation rates. In this study, however, the objective was to develop and synthesize a family of novel biodegradable polyurethanes (PUs) based on a poly(ε-caprolactone urea)urethane backbone integrating polyhedral oligomeric silsesquioxane (POSS-PCLU) with varying amounts of hard segments (24%, 28% and 33% (w/v)) in order to investigate the influence of hard segment chemistry on the degradation rate and profile. PUs lacking POSS nanoparticles served to prove the important function of POSS in maintaining the mechanical structures of the PU scaffolds before, during and after degradation. Mechanical testing of degraded samples revealed hard segment-dependent modulation of the materials’ viscoelastic properties, which was attributable to (i) degradation-induced changes in the PU crystallinity and (ii) either the presence or absence of POSS. In conclusion, this study presents a facile method of controlling degradation profiles of PU scaffolds used in tissue engineering applications.

An effective sterilisation technique that maintains structure integrity, mechanical properties, and biocompatibility is essential for the translation of new biomaterials to the clinical setting. We aimed to establish an effective sterilisation technique for a biodegradable (POSS-PCL) and nonbiodegradable (POSS-PCU) nanocomposite scaffold that maintains stem cell biocompatibility. Scaffolds were sterilised using 70% ethanol, ultraviolet radiation, bleach, antibiotic/antimycotic, ethylene oxide, gamma irradiation, argon plasma, or autoclaving. Samples were immersed in tryptone soya broth and thioglycollate medium and inspected for signs of microbial growth. Scaffold surface and mechanical and molecular weight properties were investigated. AlamarBlue viability assay of adipose derived stem cells (ADSC) seeded on scaffolds was performed to investigate metabolic activity. Confocal imaging of rhodamine phalloidin and DAPI stained ADSCs was performed to evaluate morphology. Ethylene oxide, gamma irradiation, argon plasma, autoclaving, 70% ethanol, and bleach were effective in sterilising the scaffolds. Autoclaving, gamma irradiation, and ethylene oxide led to a significant change in the molecular weight distribution of POSS-PCL and gamma irradiation and ethylene oxide to that of POSS-PCU (p<0.05). UV, ethanol, gamma irradiation, and ethylene oxide caused significant changes in the mechanical properties of POSS-PCL (p<0.05). Argon was associated with significantly higher surface wettability and ADSC metabolic activity (p<0.05). In this study, argon plasma was an effective sterilisation technique for both nonbiodegradable and biodegradable nanocomposite scaffolds. Argon plasma should be further investigated as a potential sterilisation technique for medical devices.