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Four photochromic spiropyran‐amylose (ASP) biobased polymers with different spiropyran (SP) grafting density, DS, ASP10 (DS = 0.12), ASP40 and ASP40PA60 (DS = 0.40), and ASP100 (DS = 0.97), are synthesized through azide‐alkyne cycloaddition of an alkynyl‐functional SP derivative onto C6‐azidated‐amylose (AN3), where the unconverted azide in ASP40PA60, ASP100, and the AN3 precursor are quenched by clicking with propargyl alcohol (PA). All ASPs are poorly soluble in trifluoroethanol, ethanol, and water but soluble in dimethyl sulfoxide, N,N‐dimethylformamide, and hexafluoroisopropanol irrespective of UV irradiation, switching reversibly the grafted SP into zwitterionic merocyanine (MC). Only ASP10 and ASP40 are slightly soluble in the low polarity tetrahydrofuran, with ASP40 showing a marked photochromism and reduction of solubility on SP→MC switching. The photochromism in solution is preserved in the solid state, although with significant differences between the still relatively fast SP→MC photoisomerization and the much slower thermal retro‐isomerization. The dynamics of both processes, evaluated in a thin spin–coated ASP100 film and a thicker ASP40 photoswitchable coating on glass and paper, is more clearly affected than in solution by the grafting density. Switching the nearly apolar SP into the zwitterionic MC does not significantly affect wettability of the slightly hydrophobic ASP40 coating. [ABSTRACT FROM AUTHOR]

This article presents results on the use of a new material as a solidifying agent and/or color-fixing agent. A special polysaccharide material extracted from the prickly pear cactus (Opuntia ficus indica) was tested on historical materials and modern papers. An old book from the 18th century was chosen as historical material. From the mentioned book 42 pages were taken, on which a conservation and restoration pretreatment was performed before applying the polysaccharide material: sampling, fiber analysis, dry cleaning, ink solubility, pH test, thickness measurement and wet cleaning. The paper sheets provided for the test were divided into 4 groups, 3 of which were treated with gel and one left untreated as a reference. The division into groups is not only due to the different method of application, but also due to the process of gel extraction. The effect of the treatment was analyzed using FTIR-ATR. To test the mucilage as color-fixing agent 2 samples were prepared using watercolor papers colored with 6 different watercolors applied to 2.5 cm2 samples for each color in two rows of different intensity. One of the 2 samples was treated with gel, but both were immersed for 3 times in a water-ethanol solution for approximately 20 min as is standard practice in conservation and restoration. After washing, both specimens were subjected to colorimetric analysis to assess their differences. The results provided satisfactory evidence for the protection of paints sensitive to aqueous treatments and suggest the use of mucilage as a new material in cleaning method for water-soluble media. [ABSTRACT FROM AUTHOR]

Removal of tenacious adhesives is one of the major challenges in paper conservation. This article examines what water-resistant adhesives were used from 1870 to 1920 and comments on the implications of these findings to the practising paper conservator. Water-resistant formulations were found to be more likely to contain animal glue and linseed oil as binders. Other non-water-soluble binders, such as plant resins, shellac, gutta-percha and casein, were also used, as were mixtures of starch or flour paste with animal glue. A variety of chemical hardeners were employed, including tannic acid, formaldehyde and alum. The addition of substances containing multivalent metals such as copper, lead, calcium and aluminium may also have had a hardening effect, though they may not have been added for this reason. [ABSTRACT FROM AUTHOR]

Acid catalyzed ageing of oil impregnated kraft paper has been studied experimentally. Five different carboxylic acids (formic, acetic, laevulinic, stearic and naphtenic acid) have been added to mineral oil to arrive at a neutralization value of 0,4 mg KOH/g. Thereafter, kraft paper of two different humidities has been allowed to equilibrate with the oil. The results show that the lower the molecular weight of the carboxylic acids is the more is absorbed by the paper. Furthermore, a clear synergy for the paper ageing rates between moisture and the lower molecular weight acids is found, while for the higher molecular weight acids almost no effects were found. It is concluded that present techniques for measuring acidity of oils do not reflect these detailed conditions. It is suggested to introduce a new measuring technique for neutralization value where water rinsing is used to identify the content of low molecular weight, water soluble acids. [ABSTRACT FROM AUTHOR]

There is interest in replacing inorganic fillers in paper, coatings and plastics with renewable organic fillers to improve the economics, performance and environmental aspects of such products. Starch microcellular foam (SMCF) particles are promising materials in this regard. This research was undertaken to produce SMCF particles and characterize their morphology, optical properties and interaction with water. SMCF particles were produced using corn starch; which was solubilized in water. The foam structure was created by precipitating the starch using ethanol in a solvent exchange technique. The starch was also reacted with alkyl ketene dimer (AKD) wax at different levels in order to understand if the AKD could impart water resistance to the particles. Two methods were used to incorporate AKD: (1) the AKD was coated onto foam particles after foam formation, and (2) the AKD was blended with the starch before foam particle formation. Hexane extraction was used to purify a portion of each of the samples to determine if unreacted AKD existed with the starch matrix. Particles with porous structure and high brightness were developed for all combinations of starch and AKD. The brightness of the particles was significantly higher than that of the uncooked starch, presumably due to the development of a porous structure. For the AKD coated particles a minimum amount of AKD charged was needed to develop a high contact angle, low solubility, and low water retention value, higher levels of AKD in AKD coated particles did not further alter these properties. This indicates that the changes in properties with AKD level with coated particles is a surface phenomena. Starch AKD blends did not show any increased resistance to water relative to the particles with no AKD blended. This is due to the ethanol used in the precipitation process extracting the AKD, which was confirmed by elemental analysis. The particles, even with the 10% AKD coated or blended, lost their porous structure upon rewetting. Further work needs to be performed to more effectively hydrophobize the starch foams with AKD. [Copyright &y& Elsevier]

Newly developed active pharmaceutical ingredients (API) often experience low solubility in aqueous media and thus possess poor oral bioavailability. The SmartFilm®-technology is a novel approach to overcome poor solubility. The technique uses commercial paper in which API can be loaded in amorphous state, thus increasing dissolution rate dc/dt and solubility c s when compared to bulk material. However, the preservation of the amorphous state is a prerequisite for an efficient use of the smartFilm-technology and thus the crystalline state needs to be inspected during storage. Preferably, this should be done non-destructively. Traditional techniques, such as x-ray diffraction (XRD) or differential scanning calorimetry (DSC), do not allow for non-destructive crystallinity investigations, whereas Terahertz (THz) spectroscopy is a non-destructive technique, that is sensitive to the crystalline state of many molecular crystals. Therefore, the potential of THz-spectroscopy for crystallinity state inspection of API in smartFilms and tablets made from smartFilms was investigated in this study. The THz results obtained were compared to results obtained from XRD and DSC measurements. Whereas DSC measurements failed to reliably detect crystalline API in the smartFilms, XRD and THz-spectroscopy showed similar results and revealed that it was possible to prepare smartFilms loaded with >23% (w/w) amorphous API. Results indicate the great potential of THz spectroscopy for the non-destructive determination of the crystalline state of APIs in smartFilms and/or tablets made from paper. [ABSTRACT FROM AUTHOR]