Suchergebnisse

This review is conceived as a guide for material science researchers and conservators aiming to face the problem of deterioration of contemporary artworks entirely or partially made of plastics. It initially illustrates the analytical approaches for identifying polymeric material components in 3D art objects, such as sculptures and installations, and provides a perspective of their limits and advantages. Subsequently, the methodologies used for studying the deterioration of contemporary art plastics are reviewed, emphasising the main effects of the different types of degradation (i.e., migration of additives, oxidation and hydrolysis) and suggesting the appropriate techniques for their detection. Finally, the application of artificial ageing tests is critically assessed. All the concepts are elaborated through case studies and examples ; This work was funded by the European Union H2020 project Nanorestart (646063) and the Xunta de Galicia (Centro singular de investigación de Galicia accreditation 2019-2022 ED431G 2019/03, Consolidación e estructuración ED431B 2018/16, and the European Regional Development Fund—ERDF) ; SI

In this systematic review, a total of 45,143 publications on block copolymers, issued between 1952 and 2019, are analyzed in terms of number, source, language, institution, country, keywords, and block copolymer type, to find out their evolution and predict research trends. The number of publications devoted to block copolymers has been growing for over six decades, maintaining a consistent level throughout the last few years. In their majority, documents came out of the United States, although more recently, Chinese institutions are those displaying the largest production. Keywords analysis indicated that one-third of the publications concerned synthesis, around 20% explored self-assembly and morphological aspects, and another 20% referred to block copolymer applications in solution. In particular, 2019 confirmed the expansion of studies related to drug delivery, and in minor extent, to a deeper view of self-assembling. Styrene–butadiene–styrene block copolymer was the most popular in studies covering both basic and industrially oriented aspects. Other highly investigated copolymers are PEO-b–PPO-b–PEO (Pluronic©) and amphiphilic block copolymers based on polycaprolactone or poly(lactic acid), which owed their success to their potential as delivery vehicles. Future trending topics will concern nanomedicine challenges and technology-related applications, with a special attention toward the orientation and ordering of mesophase-separated morphologies ; This research was funded by the Spanish Agencia Estatal de Investigación (PGC2018-101047). M.L. also acknowledges the Xunta de Galicia (Grupo con Potencial de Crecemento ED431B 2018/1 and Centro singular de investigación de Galicia accreditation 2019-2022, ED431G 2019/03) and the European Union (European Regional Development Fund-ERDF) ; SI

Early evidence of materials decay can provide diagnostic insights to conservators and scientists enhancing the overall knowledge on art materials. Limited knowledge is available on the long‐term behavior of synthetic and natural polymers used in art. This research poses the foundations for studies on organic materials suffering from autoxidation processes, using nondestructive surface enhanced Raman spectroscopy (SERS) for the detection of commonly present low molecular weight degradation products. Such products are here considered molecular markers for diagnostic investigations, and SERS allows detection limits never reached before. 3D aluminum (Al)‐coated SERS substrates are optimized for in situ sampling of artifacts, testing different reference materials, sampling strategies, and instrumental conditions. Linseed oil is an organic material widely used in art, which degradation mechanisms are well‐known. Considering that many polymeric compounds follow similar degradation pathways, linseed oil seemed an excellent model material for a wider research on SERS for polymers degradation in artworks ; European Union's Horizon 2020 research and innovation programme. Grant Number: Project NANORESTART (H2020‐NMP‐21‐2014/646063) ; SI

This paper provides new insights for the study of polymer degradation through the detection of markers released at the polymer surface using Al-coated SERS active substrates. Combining a nanodestructive sampling procedure with the SERS sensitivity allows achieving detection limits much lower than traditional polymer characterization techniques, opening the way to the use of SERS as part of an innovative strategy to diagnose surface degradation in polymeric museum artefacts. The method was applied to artificially photo-aged model polymers and to museum artworks ; The European Union Project NANORESTART (H2020-NMP-21-2014/646063) supported this work. ML also thanks the Xunta de Galicia (Centro singular de investigación de Galicia accreditation 2016–2019, ED431G/09) and the European Union (European Regional Development Fund - ERDF) ; SI

From 2nd to 5th October 2012 an International Congress on Science and Technology for the conservation of Cultural Heritage was held in Santiago de Compostela, Spain, organized by the Universidade of Santiago de Compostela on behalf of TechnoHeritage Network. The congress was attended by some 160 participants from 10 countries, which presented a total of 145 contributions among plenary lectures, oral, and poster communications. The congress was dedicated to eight topics, namely (1) Environmental assessment and monitoring (pollution, climate change, natural events, etc.) of Cultural Heritage

We provide fundamental guidelines in the form of a tutorial to be taken into account for the preparation and characterization of a specific class of poly(ethylene glycol) (PEG) derivatives, namely azide-terminated PEGs. Special attention is given to the effect of these chain end groups and their precursors on properties affecting the PEGylation of proteins, nanoparticles and nanostructured surfaces. Notwithstanding the presence of 13C satellite peaks, we show that 1H NMR enables not only the routine quantitative determination of chain-end substitution, but is also a unique method to calculate the absolute number average molecular weight of PEG derivatives. In the use of size exclusion chromatography to get molecular weight distributions, we highlight the importance of distinguishing between eventual secondary reactions involving molecular weight changes and the formation of PEG complexes due to residual amounts of metal cations from reactants. Finally, we show that azide end groups affect PEG melting behavior. In contrast to oxygen-containing end groups, azides do not interact with PEG segments, thus inducing defect formation in the crystal lattice and the reduction of crystal sizes. Melting temperature and degree of crystallinity decrease become especially relevant for PEGs with very low molecular weight, and its comprehension is particularly important for solid-state applications ; This research was funded by the Spanish Agencia Estatal de Investigación (PGC2018-101047). M.L. also acknowledges the Xunta de Galicia (Grupo con Potencial de Crecemento ED431B 2018/1 and Centro singular de investigación de Galicia accreditation 2019-2022, ED431G 2019/03) and the European Union (European Regional Development Fund-ERDF) ; SI