Cyclododecane Research Articles

Preliminary assessment of new single and blended volatile binding media for temporary consolidation of cultural heritage

Volatile Binding Media (VBM) are waxy solids that can be used for temporary consolidation of heritage artifacts and architectural surfaces thanks to their spontaneous sublimation at room temperature. They are used to temporary shelter, consolidate or protect materials during high-risk operation, such as excavation, transportation, water-based treatments, etc. Although they are employed since the 1990s, research focused almost entirely on one of them, cyclododecane (CDD), which is by far the most used in onsite applications. However, CDD exhibits some drawbacks, including a fixed sublimation speed that hardly fits into all the possible applications and climates, hence the development of new VBM is strongly needed. In recent years, a certain attention was addressed to menthol as a possible alternative, but the research on other possible substitutes is still lacking. In this paper, a range of different VBM for temporary consolidation of cultural heritage materials was prepared and investigated, including five pure compounds (CDD, cyclododecanol, cyclododecanone, menthol and camphene) and fifteen mixes. These new materials are expected to provide tunable properties in terms of melting temperatures and sublimation rates, allowing their use in a variety of climatic contexts and applications, and to exhibit better properties for onsite applications compared to CDD, such as lower flash point, lower hazard for conservators’ health and/or higher availability.

Solvent-free transfer of monolayer graphene with recrystallized cyclododecane

Graphene produced by chemical vapor deposition finds applications in a wide range of technologies. However, the transfer of monolayer graphene from the native substrate (commonly Cu foils) to a desired substrate remains challenging. In this study, we report a solvent-free transfer technique for monolayer graphene using a sublimable supporting coating, cyclododecane (CDD). After spin-coating CDD on graphene grown on Cu foil, we rapidly heat the stack at 80 °C to melt and recrystallize the CDD coating. The recrystallized coating top surface becomes composed of larger and interconnected CDD crystals, which form a mechanically strong coating that takes almost 2 h to sublimate completely. Having a bottom surface that closely conforms to graphene's topography, the CDD coating can effectively support graphene during the whole transfer process without compromising its structural integrity, maintaining its superior electrical and optical properties. In this way, CDD becomes capable of transferring monolayer graphene over square centimeter areas. Unlike traditional polymer-based techniques, after transfer, the CDD coating sublimates completely, without the need of any post-transfer cleaning treatment. Our work shows that the CDD coating can be an alternative transfer medium for the efficient and clean transfer of monolayer graphene. This technique paves the way for the widespread adoption of graphene in various applications, including those not compatible with solvents.

Cyclododecane shaping, sublimation rate and residue analysis for the extraction of painting micro-samples from resin cross-sections

Cross-section preparation of painting micro-samples is part of their routine analysis. This type of preparation can be used for several analytical techniques, such as scanning electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and optical microscopy. These techniques offer high-resolution imaging and/or elemental information, providing access to technical and material data important for the interpretation, preservation, and restoration of painted artworks. However, it also means that the material from the sample embedded in the resin becomes unreachable for further analysis, except for the polished surface of the cross-section. Degradation of the embedding medium can also occur over time, which can lead to misinterpretation, loss of information, or even complete destruction of the embedded sample. In the field of cultural heritage, cyclododecane (CDD) is commonly used for the consolidation and protection of objects, and is used in the preparation of cross-sections to prevent contamination of the sample by the embedding medium. This study enhanced the existing preparation process by shaping the CDD layer to enable extraction of the micro-sample from the resin if needed, without compromising the integrity of the sample. Moreover, the purity, the sublimation rate in a normal environment and a vacuum, and the impact of CDD on three different types of samples (historical painting on a canvas, wall painting fragment, model sample) were examined.

A three-dimensional nerve guide conduit based on graphene foam/polycaprolactone

In this study, a novel nerve guide conduit was developed, based on a three-dimensional (3D) graphene conductive core grown, by chemical vapor deposition (CVD) coupled with a polycaprolactone (PCL) polymer coating. Firstly, the monolithic 3D-graphene foam (3D-GF) was synthesized on Ni foam templates via inductive heating CVD, subsequently, Ni/Graphene samples were dipped successively in PCL and cyclododecane (CDD) solutions prior to the removal of Ni from the 3D-GF/PCL scaffold in FeCl3. Our results showed that the electrical conductivity of the polymer composites reached to 25 S.m-1 after incorporation of 3D-GF. Moreover, the mechanical properties of 3D-GF/PCL composite scaffold were enhanced with respect to the same geometry of PCL scaffolds. The wettability, surface porosity, and morphology did not show any significant changes, while the PC12 cell proliferation and extension were increased for the developed 3D-GF/PCL nanocomposite. It can be concluded that 3D-GF/PCL nanocomposites could be good candidates to utilize as a versatile system for the engineering of peripheral nerve tissue.

Fabrication of 3D monolithic graphene foam/polycaprolactone porous nanocomposites for bioapplications

Aiming at the production of light, porous, conductive, biosafe composites, in this paper we are presenting a novel fabrication method for monolithic, three-dimensional (3D) graphene foam (GF)/porous polymer composites. The synthesis adopts a novel process architecture by using Ni foam templates in an inductive heating chemical vapor deposition growth process, and by removing Ni chemically while retaining graphene integrity by the reversible application of cyclododecane (CD); finally, nondestructive coating procedures with polycaprolactone (PCL) solutions have been developed. The composites can be optimized to enhance electrical conduction, flexibility and mechanical properties, while mixing PCL and CD allows to coat the GF with a novel mesoporous polymer coating. By tuning the GF properties, the typical electrical resistance of the 3D forms can be reduced to a few 10 s of Ohms, values that are maintained after the PCL coatings. The current study achieved a GF fraction ranging between 1 and 7.3 wt%, with even the lower graphene content composites showing acceptable electrical and mechanical properties. The properties of these conductive 3D-GF/PCL composites are in line with the requirements for applications in the field of nerve tissue engineering.Graphical abstract

Removal of Bats’ Excreta from Water-Soluble Wall Paintings Using Temporary Hydrophobic Coating

ABSTRACT The removal of bats’ excreta from the decorative surfaces of India’s Ajanta cave (2nd BCE to 5th CE) was always feared due to the water solubility of the plaster and the binding glue in the paint layer. Although the caves are now free from bats, their heavy discharge in the past is having a telling impact in the form of damage to painted plasters and basaltic rock surfaces. Studies undertaken through FTIR, Raman spectroscopy, SEM-EDS, ion strip tests, etc. showed guano seeped deep into the earthen support through the paint layer. In the present work Cyclododecane (CDD), a volatile binder and reversible consolidant, was utilized to protect the infested paint layer from any water ingress and the surface was successfully cleaned with phytagel and de-ionized water. The two-step process cleaned guano from water-sensitive painted surfaces by selective masking with CDD which sublimed in few months leaving no visual residues on the substrate. This hydrophobic process of cleaning is certainly advantageous to other aqueous methods that may cause damage to the proteinaceous binder, found mixed in the paint and earthen plaster layers at Ajanta. The process can now be successfully applied to similar other sites in India and elsewhere for guano removal.

The effects of cyclododecane and subsequent removal on δ15N, δ13C, and δ18O values in collagen and bioapatite of a modern bone

Applying consolidants to bone material in museum collections often is necessary to stabilize fragile specimens. However, this process can be difficult to reverse and may chemically alter the material, which may affect future biochemical analyses. Cyclododecane (CDD), a pliable solid that sublimates at room temperature, is a potential reversible alternative for temporary consolidation. This study examined the effects of CDD and Shell Cyclosol 53 (C53 – a solvent commonly used with CDD) on stable nitrogen, carbon, and oxygen isotope values in a modern whale rib. Different application methods (penetrating hot melt vs. surface heat spatula) and removal methods (low heat, ambient sublimation, and solvent) were tested in various combinations. The most effective method for removing CDD was low heat (65 °C); applying C53 also proved a viable option. All stable isotope values were unaffected by CDD application and solvent. No alteration was observed which suggests CDD does not affect the bone tissue structure, nor does it facilitate isotopic exchange or fractionation. This is an improvement over certain permanent consolidants which can alter bioapatite oxygen isotope values in particular. CDD is a viable temporary consolidant when further chemical analyses of bone tissue are desired.

A sublimate sorbent for stir-bar sorptive extraction of aqueous endocrine disruptor pesticides for gas chromatography-electron capture detection

A dumbbell-shaped magnetic stir-bar with sublimate sorbent was prepared for the stir bar sorptive extraction (SBSE) of pesticides in an aqueous sample prior to gas chromatography-micro-electron capture detection (GC-μECD). Cyclododecane (CDD) was coated onto a magnetic stir-bar surface as a sublimate sorbent, and steel balls were placed on both ends to form a dumbbell-shaped magnetic stir-bar for SBSE. Four EDC pesticides including chlorpyrifos, ethion, bromopropylate, and λ-cyhalothrin in aqueous samples were selected as model species to examine the proposed SBSE and the following desorption.The parameters studied were those affecting the extraction efficiencies including the coating (solvent for CDD and thickness), extraction (sample pH, stirring rate, time, and salting out effect), dissolution solvent volume, and the loss of CDD sublimated in air. The maximum extraction efficiency was obtained under the following conditions. The stir bar (with CDD thickness of 5.2 μm) was added into a 10 mL sample solution (at pH 7) for a 20-min extraction at 600 rpm. Then, the stir bar was gently removed from the sample solution, disassembled, and immersed into a 0.2 mL insert tube consisting of 3 μL hexane to dissolve; 1 μL was used for GC-ECD analysis. The linear ranges were 0.005–5 μg L−1 with coefficients of determination ranging from 0.9950 - 0.9994. Detection limits (based on S/N = 3) of the four EDCs were 0.4–4.5 ngL-1 with a relative standard deviation (RSD) of 2.4–6.3%, and quantitation limits (based on S/N = 5) were 1–15 ngL−1. The relative recoveries of the spiked samples were in the range of 83.2–98.7% with RSDs of 2.1–8.4% in farm field waters. The proposed sublimation sorbent obtained excellent enrichment factors (101–834) and provided a simple, rapid, sensitive, and eco-friendly sample preparation method.

Laboratory Research into the Use of Menthol as a Temporary Consolidant for Conservation on Archaeological Excavations

Due to its ability to evaporate completely at room temperature, menthol has recently been proposed for use as a new kind of temporary consolidant at the excavation site of Qin Shihuang's Terracotta Army. Compared to cyclododecane (CDD), the most widely used temporary consolidant, menthol has the advantages of a longer working time, a well‐established safety profile and easy local availability. In this paper, in order to better understand the temporary consolidation behaviour of menthol and to guide its optimal use in the field, laboratory experiments are carried out on ISO standard sand substrate in conditions mimicking the situation of an archaeological excavation. Basic and important knowledge about menthol, which is related to its effectiveness in temporary consolidation, such as penetration into the substrates, the solidification process and the degradation of the efficiency of consolidation over the sublimation time, are systematically studied. The results show that the penetration of menthol is notably affected by the substrate's temperature, particle size, particle‐size distribution and water content. The solidification of melted menthol is an obvious volume shrinkage process, and the shrinkage extent is greatly affected by the application protocol. The consolidated samples experience a dramatic promotion in compressive strength, and as menthol volatilizes, the consolidated samples will eventually become loose and finally collapse.

The Influence of Temperature on the Application of Cyclododecane in Paper Conservation

AbstractIn paper conservation, cyclododecane (CDD) is commonly used to waterproof water-sensitive inks and paints. In order to apply CDD over thin lines (such as those of drawings or signatures), conservators often use

A non‐invasive NMR relaxometric characterization of the cyclododecane–solvent system inside porous substrates

With the aim of deepening the knowledge on the behavior of cyclododecane (CDD) as a temporary consolidant agent for weathered stones, NMR longitudinal and transverse relaxation decays have been exploited to follow the distribution of cyclododecane solutions into porous matrices. By measuring as function of time the relaxation decay constants of CDD solutions dropped onto porous supports, it has been possible to differentiate the step encompassing the solvent evaporation, which determines the consolidant migration within the matrix, from that governing the consolidant sublimation, which is related to the consolidation effectiveness over time.

A non-invasive investigation of cyclododecane kinetics in porous matrices by near-infrared spectroscopy and NMR in-depth profilometry

a b s t r a c t In order to evaluate the effectiveness of cyclododecane (CDD) as a temporary protective coating and consolidating agent for fragile stone materials, this paper focuses on its physicochemical behaviour in terms of its penetration into porous matrices and subsequent sublimation. In particular, a near-infrared spectroscopy (NIR) and NMR in-depth profilometry study has been carried out by monitoring the evap- oration/sublimation process of CDD solutions as a function of time. By means of this non-invasive multitechnique approach, the behavior of CDD both on the surface and inside the first millimeters of the stones has been adequately described. It has also been highlighted how the progression of CDD's dis- appearance within different stones is affected by both substrate porosity and boiling point of the carrier solvent. These results demonstrate the potential of such a method of protocol for non-invasive in situ monitoring of the unconstrained sublimation process of this temporary protective agent.

Studies on partial hydrogenation of 1,5,9-cyclo-dodecatriene towards cyclo-dodecene

The selective hydrogenation of 1,5,9- cis, trans, trans-cyclo-dodecatriene (1,5,9- ctt-CDT) towards cyclo-dodecene (CDE) depends strongly on the pressure of hydrogen, respectively the hydrogenation rate. High yields of CDE (>90%) can only be reached at extremely low hydrogen pressure. In order to elucidate this exceptional reaction performance the course of reaction has been studied for a wide range of hydrogen pressure, 0.01 > p H 2 > 2.5 MPa , taking into consideration data of other research groups. The CDT hydrogenations were discontinuously carried out in liquid phase on Pd/Al 2O 3 at T = 353 K. The resulting hypothesis of this study is that the very low reaction rate at low p H 2 is necessary in order to realize a dense surface coverage of 1,5,9-CDT and 1,5-cyclo-dodecadiene (CDD) isomers where these molecules show adsorption on Pd via two double bonds so that readsorption of formed CDE and subsequent hydrogenation to cyclo-dodecane (CDA) is hardly possible. On the whole this new hypothesis on the reaction course of CDT hydrogenation gives a sound and fully consistent view on this rather complicated reaction.

The study of cyclododecane as a temporary coating for marble by NMR profilometry and FTIR reflectance spectroscopies

This contribution focuses on an analytical evaluation of the use of cyclododecane (CDD) (C12H24) as a temporary protective coating for non-porous stone materials of cultural heritage interest.

Highly selective synthesis of cyclododecanone over mesostructured VSBA-15 catalysts

Highly ordered VSBA-15 mesoporous catalysts have been synthesized under pH-adjusting direct hydrothermal (pH-aDH) method using vanadyl sulphate hydrate and Pluronic P123 as the sources of vanadium and template, respectively. The mesoporous catalysts characterized by sophisticated instrumental techniques, viz. ICP-AES, XRD, N 2 adsorption, ESR, UV–vis DRS, 51V MAS NMR, 29Si MAS NMR and TEM show their two-dimensional mesostructures with tetrahedral vanadium species on the silica surface. The well ordered VSBA-15 catalysts have been used in the oxidation of cyclododecane (CDD) with hydrogen peroxide (H 2O 2, 30%) to find their catalytic activities. The regenerated VSBA-15 catalysts have been examined to find their catalytic stabilities. VSBA-15(5) catalyst has been washed with ammonium acetate solution to investigate the leaching of vanadium species in the framework of silica network of SBA-15, and the catalytic activity of washed VSBA-15(5) has also been examined in the catalytic reactions. Moreover, the hydrothermally stable VSBA-15(5) catalyst has also been examined in the catalytic reaction to find the effect of its catalytic activity. Additionally, the influences of various reaction parameters such as temperature, time, ratios of reactant and solvents on the oxidation of CDD have been investigated. Based on the catalytic results, VSBA-15(5) catalyst is found to be a highly active, recyclable and promising heterogeneous catalyst for selective synthesis of cyclododecanone (CDD O).

The uses of cyclododecane in conservation

The uses of cyclododecane in conservation

Study of the kinetics and mechanism of the liquid-phase oxidation of cyclododecane by molecular oxygen—III. Kinetics of the decomposition of cyclododecyl hydroperoxide

Study of the kinetics and mechanism of the liquid-phase oxidation of cyclododecane by molecular oxygen—III. Kinetics of the decomposition of cyclododecyl hydroperoxide

Properties of carbonaceous films on quartz substrate prepared from cyclododecane

The nature of carbonaceous film prepared from cyclododecane (CD) is examined in comparison with that from bisphenol A (BPA). The electrical conductivity of CD film is slightly lower than that of BPA film, although both films exhibit semiconductive properties. Investigations of X-ray diffraction, transmission electron micrographs and laser Raman spectra data demonstrate that the CD film obtained appears to have an amorphous-like structure, whereas the BPA film has, at least in part, slightly ordered microregions.

Observation of Substructures in Photoinert Organic Single Crystals doped with Photoactive Impurities

THE photoexcitation properties of organic crystals have generally been studied for pure or mixed aromatic single crystals. In these cases the host is photoactive1–3. The substructures of such molecular crystals are not as well known as in the cases of ionic4 and metallic crystals5, although such structures may well influence the properties involved in photoexcitation. D. J. M. and Irons6 used cyclododecane (CDD) single crystals as the photoinert host for phosphorescence lifetime studies of the photoexcited triplet state of dissolved aromatic impurities. Lifetime variations were found and these were attributed to various states of aggregation of the photoactive solute species in the single crystal host. The tendency to aggregate was correlated to lattice mismatch between host and dopant molecular dimensions. The present work establishes the presence of aggregates in doped single crystals of CDD (cyclododecane) by direct observation.