9Poly lactide-co-glycolide (PLGA) is an important polymer matrix used to provide sustained 10 release across a range of active pharmaceutical ingredients (APIs) and works by hydrolytic 11 degradation within the body, thereby releasing entrapped drug. Processing and sterilisation 12 can impact on the morphology and chemistry of PLGA therefore influencing the hydrolysis 13 rate and in turn the release rate of any entrapped API. This paper has looked at the effect of 14 supercritical carbon dioxide (scCO 2 ) processing, gamma irradiation, comonomer ratio and 15 temperature on the hydrolysis of individual PLGA microparticles, using a combination of 16 Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) imaging, Scanning 17 Electron Microscopy (SEM), Differential Scanning Calorimetery (DSC) and Gel Permeation 18 chromatography (GPC) to facilitate a better understanding of the physiochemical factors 19affecting the hydrolysis rate. This work has shown that scCO 2 processing influences 20 hydrolysis rates by increasing the porosity of the PLGA microparticles, increasing the lactide 21 comonomer ratio decreases hydrolysis rates by reducing the hydrophilicity of the PLGA 22 microparticles and increasing the gamma irradiation dose systematically increases the rate of 23 hydrolysis due to reducing the overall molecular weight of the polymer matrix via a chain 24 scission mechanism. Moreover this work shows that ATR-FTIR imaging facilitates the 25 determination of a range of physicochemical parameters during the hydrolysis of a single 26 PLGA microparticle including water ingress, water/polymer interface dimensions, 27 degradation product distribution and hydrolysis rates for both lactide and glycolide 28 copolymer units from the same experiment. 29

With a multitude of potential applications, poly­(phosphine–borane)­s are an interesting class of polymer comprising main-group elements within the inorganic polymer backbone. A new family of primary alkylphosphine–borane polymers was synthesized by a solvent-free rhodium-catalyzed dehydrocoupling reaction and characterized by conventional chemicophysical techniques. The thermal stability of the polymers is strongly affected by the size and shape of the alkyl side chain with longer substituents imparting greater stability. The polymers show substantial stability toward UV illumination and immersion in water; however, they undergo a loss of alkylphosphine units during thermal degradation. The polymers exhibit glass transition temperatures (T g) as low as −70 °C. A group interaction model (GIM) framework was developed to allow the semiquantitative prediction of T g values, and the properties of the materials in this study were used to validate the model.

The effects of thermo-mechanical auxetic foam conversion parameters on the Young's modulus and Poisson's ratio of open-cell polyurethane foam are related to changes in chemical bonding and cell structure. Applied volumetric compression, conversion temperature, and duration are reported on foam Young's modulus, Poisson's ratio, and structural stability. Fourier transform infrared spectral analysis on samples converted at and above 160 C strongly indicates a hydrogen bond interaction increase in urea groups (C¼O---H-N) and an increase in hydrogen bonding population. Spectral changes inferred soft segment degradation following extensive heat exposure (200 C, 180 min), specifically a shift and intensity change in CH 2 and C-O-C polyol bands and a broad baseline increase between 3600 and 2400 cm À1 . These changes are linked to (i) resistance to dimensional recovery over time and during re-heating; (ii) Poisson's ratio becoming negative, then zero in tension or marginally positive in compression; (iii) Young's Modulus reducing then increasing; (iv) mass loss, evidenced by thermogravimetric analysis increasing from 150 C. The minimum mean values of Poisson's ratio of %À0.2 (to 10% compression/tension) are comparable to other studies. All samples that retain their imposed compression over time are isotropic, with near constant Young's moduli and Poisson's ratio (to 10% compression/tension).

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Composite films were formed by incorporating three different bentonites into an ethylene modified, water‐soluble poly(vinyl alcohol), EPVOH. The interaction of EPVOH with both hydrophilic and hydrophobic bentonites was investigated. EPVOH provided lower water vapor and oxygen transmission rates compared to a conventional PVOH grade when exposed at high relative humidities (70–90% RH). EPVOH films which exhibited oxygen barrier properties comparable to that of a biaxially oriented PET packaging film at 80% RH were produced. High compatibility between EPVOH and hydrophilic bentonites provided an even distribution of clay platelets in the composites. A strong increase in Young's modulus with increased addition of any of the three bentonites was found. At low addition levels the hydrophobic bentonite proved to be effective in terms of maintaining high elongation at break, high transparency and high gloss. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41737.

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Selected instrumental techniques [dilatometry, thermogravimetry – mass spectrometry (TG‐MS), and variable temperature – diffuse reflectance infrared Fourier transform spectroscopy (VT‐DRIFTS)] have been used to investigate the role of moisture in the rehydroxylation reaction which causes expansion and mass gain in fired clay ceramics. The temperature range over which adsorbed water molecules and structural hydroxyl groups are desorbed from fired clay ceramic as it is reheated, and the nature of the structural hydroxyls that are formed as the ceramic is cooled and then held under controlled conditions have been explored. The mass chromatogram for m/z = 18, supported by VT‐DRIFTS, showed that physisorbed water molecules were removed from the ceramic at about 105°C, whereas strongly bound molecules of water and structural hydroxyls were held to ≤500°C. Dilatometry revealed a marked contraction of the ceramic between 200°C and 330°C which corresponded to loss of strongly bound molecules of water. The VT‐DRIFTS also showed that the interaction of water molecules with the ceramic body following reheating occurred in two stages and confirmed the kinetic law previously derived from mass gain and moisture expansion in fired clay ceramics.

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