This paper reports the solvent-free synthesis of a series of six fluoride responsive debond-ondemand polyurethane (PU) adhesives that contain a silyl functionalised degradable unit (DU). To optimise the adhesion strength and debonding nature of the adhesives, the chemical composition of the PUs was varied according to the structure of the polyol or the diisocyanate component in the polymer mainchain. 1 H NMR spectroscopy was used to study the depolymerisation behaviour in solution state. It showed that tetra-butylammonium fluoride (TBAF) triggered the breakdown of the DU unit without fragmenting the polyol mainchain indiscriminately. On exposure to fluoride ions, the PUs underwent depolymerisation with reductions in Mn ranging from 64-90 % as measured by GPC analysis. The morphology and thermal properties of the PUs were characterised by differential scanning calorimetry (DSC), rheology and variable temperature (VT) SAXS/WAXS analysis. Each technique demonstrated the reversibility of the supramolecular polymer network under thermal stimuli. PUs containing poly(butadiene) soft segments were amorphous with glass transition and viscoelastic transition temperatures dependent on the nature of the soft segment and diisocyanate starting materials. The PU containing a polyester soft segment exhibited a defined melting point at 49 °C. Mechanical stress-strain analysis of the series of PUs showed each exhibited greater than 70 % reduction in toughness after treatment with TBAF for 30 minutes as a consequence of the chemo-responsive degradation of the polymer mainchain. The material featuring an ester-based polyol demonstrated excellent adhesion at bonding temperatures as low as 60 °C. Moreover, this material could be thermally rebonded if broken by force without loss in adhesion strength over three debond-rebond cycles. Lap shear adhesion tests showed a reduction in adhesive strength of approximately 40 % (from 11.4 MPa to 7.3 MPa) on exposure to fluoride ions.

Infrared (IR) Spectroscopy and microspectroscopy (μ-IR) supported by Environmental Scanning Electron Microscope-Energy Dispersive X-Ray analysis (ESEM-EDX) has been utilised to investigate the technology and use of multicoloured architectural plasters and pigments by Neolithic communities at the archaeological site of Bestansur, Iraq, c. 7,600 BC. Sub-samples of architectural materials and pigments were analysed using IR spectroscopy and fragile samples and thin sections were analysed using μ-IR and ESEM-EDX to determine the mineralogical and elemental composition of individual components and layers and the history of construction and use of three large rectilinear buildings. In addition, experimental investigations were undertaken into the application of IR to study of the firing of calcium carbonate and of clays to investigate if this technique was able to detect evidence of fired-lime materials and of reddening of building materials by fire. Whilst the IR analysis alone was not able to characterise the plasters and pigments, when combined with ESEM-EDX the minerals responsible for pigmentation in the samples were clearly identified. The green clay was determined to be local celadonite-bearing marine clays. The red pigment was found to contain iron, most likely in the form of hematite. The black pigment contained manganese and iron, likely to be present as manganese dioxide and magnetite. The investigations of firing indicate that a hard white exterior may come from fired-lime while a reddish silty clay wall surface had probably not been subject to high-temperature burning. Analysis of a series of wall plasters and pigments from Building 8 (pre-7,600 BC) revealed experiment and development in technologies and materials throughout the occupation of the building, which in the final sequence resemble those from significantly later level at the site of Çatalhöyük, Turkey (c. 7,000 BC).

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