Maurizio Licchelli’s research while affiliated with University of Pavia and other places


Ad

What is this page?


This page lists works of an author who doesn't have a ResearchGate profile or hasn't added the works to their profile yet. It is automatically generated from public (personal) data to further our legitimate goal of comprehensive and accurate scientific recordkeeping. If you are this author and want this page removed, please let us know.

Publications (271)


A sketch of the internal side of the double bass (on the left) and the wood bottom block of the instrument (on the right) with the label highlighted by a red rectangle.
¹H NMR spectrum of Alg (sodium alginate), PTAP (pentaerythritol tris[3‐(1‐aziridinyl)propionate]), and Alg‐PTAP. Characteristic peaks are denoted.
Graphical representation of the chemical structure of CA‐CHEM gels and reagents (top) and FTIR‐ATR spectra of the gels prepared with different PTAP content, in the range 2000–1300 cm⁻¹. Ester bands are marked with an asterisk at 1725 cm⁻¹.
SEM images of the surface of CA (a‐b), CA‐CHEM‐0.5 (c‐d), CA‐CHEM‐1 (e‐f), and CA‐CHEM‐2 (g‐h) at different magnifications.
TGA curves from room temperature to 350 °C (a) and DTG traces from 180 °C to 350 °C (b) curves for CA and CA‐CHEM gels obtained with different PTAP content.

+2

Chemically Crosslinked Alginate Hydrogel with Polyaziridine: Effects on Physicochemical Properties and Promising Applications
  • Article
  • Full-text available

December 2024

·

46 Reads

ChemPlusChem

·

·

·

[...]

·

Alginate biopolymer is widely employed in many industrial fields thanks to its pleasing features of biodegradability, biocompatibility, low toxicity, and relatively low cost. The gelling process of alginate with divalent cations is fairly simple and thus it is used as a versatile biomaterial to tailor the desired mechanical and moisture properties. This study focused on developing new gel formulations to enhance the properties of calcium‐alginate hydrogel (CA). The newly synthesized hydrogels, referred to as CA‐CHEM gels, were chemically cross‐linked with different ratios of pentaerythritol tris[3‐(1‐aziridinyl)propionate] (PTAP) through the reaction between the carboxylic groups of alginate and aziridines of PTAP. The reaction was successfully monitored by NMR. The new CA‐CHEM gels were chemically characterized using FTIR‐ATR, while SEM analysis confirmed the changes in the porosity and homogeneity of the network. Additionally, thermogravimetric analyses and mechanical properties showed improvement in degradation stability and in structural strength, compared to plain CA, with an increasing PTAP content up to 1 % w/w. Finally, the new CA‐CHEM gels effectively controlled water absorption and release. In particular, CA‐CHEM‐1 performed as the most controlled system, making it promising for delivering aqueous cleaning solutions on water‐sensitive surfaces such as a wooden historical musical instrument.

Download


Figure 10. Micro-FTIR (ATR mode) mapping analysis performed on the 35 d coated LS surface before and after applying the NSE-loaded hydrogel. Upper side from the left: (a) the examined specimen with a vertical bar separating the coated surface on the left from the cleaned one on the right; (b) the examined area with the analysis points and their distances; (c) the resulting false-color µ-FTIR map. Lower side: FTIR spectra taken at different points in the examined area (from 0 to 400 µm distance); vertical bar indicates the position of the carbonyl stretching peak characteristic of the polyacrylate coating.
The results of the EDS semi-quantitative analysis of both LS and AS (wt% of carbon): uncoated, coated, and after cleaning with two different emulsions (unaged and 35 d aged).
The contact angle measurements, α (°) of the coated stones before and after the ageing cycles (35 days) and after cleaning using the two different emulsions.
Removing Aged Polymer Coatings from Porous Stone Surfaces Using the Gel Cleaning Method

April 2024

·

136 Reads

·

2 Citations

Coatings

Acrylic polymers were extensively used in past restoration practices, usually as consolidants or protecting agents. Their removal is often required because polymer coatings can improve some decay processes of stone substrates and, after ageing, may generate undesirable materials on the surface of artifacts. Therefore, the removal of old polymer coating from the surface of artifacts has become a common operation in the conservation of cultural heritage. As with other cleaning operations, it is a delicate process that may irreversibly damage the artifacts if not correctly carried out. The main aim of this study was to determine the appropriate cleaning procedure for efficiently removing old acrylic polymers (e.g., Paraloid B-72) from the surface of historical buildings. For this purpose, a polymer was applied to two different porous stone substrates (bio-calcarenite and arenaria stone). The hydrogel cleaning approach was used for the present study, as preliminary results suggested that it is the most promising polymer-removing method. The considered hydrogel (based on a semi-interpenetrating polymer network involving poly(2-hydroxyethyl methacrylate) and polyvinylpyrrolidone) was prepared and characterized using different techniques in order to assess the gel’s properties, including the gel content, equilibrium water content, retention capability, hardness, Young’s modulus, and morphology. After that, the hydrogel was loaded with appropriate amounts of nano-structured emulsions (NSEs) containing a surfactant (EcoSufTM), organic solvents, and H2O, then applied onto the coated surfaces. Moreover, plain EcoSurfTM in a water emulsion (EcoSurf/H2O) was also used to understand the polymer-removing behavior of the surfactant without any organic solvent. A comparative study was carried out on artificially aged and unaged polymer-coated samples to better understand the cleaning effectiveness of the considered emulsions for removing decayed polymer coatings. The experimental results showed that the NSE-loaded hydrogel cleaning method was more effective than other common cleaning procedures (e.g., cellulose pulp method). In fact, only one cleaning step was enough to remove the polymeric material from the stone surfaces without affecting their original properties.


Recent Advances in the Application of Metal Oxide Nanomaterials for the Conservation of Stone Artefacts, Ecotoxicological Impact and Preventive Measures

February 2024

·

88 Reads

·

5 Citations

Coatings

Due to the ongoing threat of degradation of artefacts and monuments, the conservation of cultural heritage items has been gaining prominence on the global scale. Thus, finding suitable approaches that can preserve these materials while keeping their natural aspect of is crucial. In particular, preventive conservation is an approach that aims to control deterioration before it happens in order to decrease the need for the intervention. Several techniques have been developed in this context. Notably, the application of coatings made of metal oxide nanomaterials dispersed in polymer matrix can be effectively address stone heritage deterioration issues. In particular, metal oxide nanomaterials (TiO2, ZnO, CuO, and MgO) with self-cleaning and antimicrobial activity have been considered as possible cultural heritage conservative materials. Metal oxide nanomaterials have been used to strengthen heritage items in several studies. This review seeks to update the knowledge of different kinds of metal oxide nanomaterials, especially nanoparticles and nanocomposites, that have been employed in the preservation and consolidation of heritage items over the last 10 years. Notably, the transport of nanomaterials in diverse environments is undoubtedly not well understood. Therefore, controlling their effects on various neighbouring non-target organisms and ecological processes is crucial.


Stradivari’s Varnish Revisited: Feature Improvements Using Chemical Modification

September 2023

·

234 Reads

·

3 Citations

Polymers

The most widespread varnish formulations used by master violin-makers of the “Italian Golden Age”, including Antonio Stradivari, were based on mixtures of siccative oils (e.g., linseed oil) and natural resins (e.g., colophony). Similar formulations are still used for the finish of contemporary instruments. Although most precious violins made by Stradivari and other Cremonese Masters are kept in museums, several instruments are still played and their finish may undergo deterioration due to contact with the players. Moreover, the decay of the traditional varnish may occur due to mechanical stress and natural aging caused by environmental agents (e.g., exposure to uncontrolled light, humidity, and temperature changes). The main aim of this research work is to investigate the possible improvement of varnish resistance to the decay induced by different aging processes. For this purpose, the traditional varnish (linseed oil/colophony 3:1 w/w) was recreated in the laboratory following an ancient recipe and then it was functionalized with a cross-linking agent (3-Glycidyloxypropyltrimethoxysilane, GLYMO). Plain and functionalized varnishes underwent artificial aging (UV light, temperature, and humidity variations), and their properties were comparatively studied using different techniques. All the results suggest that the functionalized varnish displays improved resistance to the aging process and particularly enhanced photostability and increased hardness (resistance to scratches).


Nanostructured Emulsions as Smart Cleaning Materials for Removing Aged Polymer Coatings from Stone Substrates

May 2023

·

93 Reads

·

6 Citations

Sustainability

Cleaning is one of the most important, essential, and delicate operation which has to be handled by conservators before applying new materials to any substrates. In past decades, nanotechnology introduced new concepts and materials in the conservation field, which have been providing many advantageous performances, especially higher than older materials. As a result, the conservators have already started to use nanomaterials in the cleaning processes of artifacts. Taking into consideration this new approach, our study has focused on using nano-structured emulsions (NSE) as smart cleaning materials for removing polymer coatings (e.g., acrylic polymers). For this purpose, Paraloid B-72 was applied on three different substrates (glass, Lecce stone, and Arenaria stone) and cleaning was performed by a specific nano-structured emulsion (NSE) based on an eco-friendly surfactant (EcoSurf) and two organic solvents in different proportions. In order to better understand the interaction of surfactant and organic solvents with polymer coating, plain EcoSurf in water was also used for comparison. In this study, the decay process of the considered polymer was also deeply studied, because it directly affects the cleaning effectiveness. Coated specimens of the different substrates were artificially aged and examined by different techniques: chromatic variations and contact angle measurements, optical microscopy, FTIR, and SEM-EDS. This material characterization process is important to understand the colour, morphology, and micro-structural difference, and the changes of hydrophobic behaviour as well as chemical composition of Paraloid B-72 polymer due to different ageing processes. After that, substrates coated with both unaged and aged polymer were cleaned by NSE according to the direct-contact procedure and cellulose pulp method. Preliminary analyses suggested that the direct-contact cleaning performed by nano-emulsion (i.e., NSE) induced a complete removal of the acrylic polymer, despite that this method is not recommended for the artifacts and can be hardly applicable in real cases. On the other hand, experimental results showed that satisfactory cleaning of stone substrates can be obtained by using NSE/the cellulose pulp system.


Figure 1. Silver nanoparticles' application in different domains [66-68].
Silver Nanoparticles in the Cultural Heritage Conservation

February 2023

·

226 Reads

Our cultural heritage is our invaluable social and environmental resource and concern. Moreover, it is a key global economic driver. However, they are subjected to deterioration process and aging. Particularly, microorganisms are nowadays considered harmful agents of biodeterioration of artistic materials due to the fact that their interactions with the material cause not only an esthetical damage due to their visible growth on the surface, but they may affect the interested materials in different ways and at different degrees via mechanical and biochemical processes leading to the formation of pitting, scaling and, in the worst scenario, to the loss of material by its detachment. To protect our shared tangible cultural heritage from biodeterioration and preserve it for future generations, several methods have been developed. Notably, using nanomaterials, with antimicrobial features, has been considered an interesting and economical method to preserve valuable heritage materials. In this chapter, we will present an overview of the decay mechanisms that participate in the deterioration of tangible artworks, in particular microorganisms’ colonization. Next, current works that have been developed to use silver nanoparticles to protect heritage items from microbial colonization and prevent their deterioration have been detailed.



Figure 6. Photovoltaic parameters extrapolated during long-term stability tests.
Photovoltaic parameters for DSSCs based on PMMA and nanoclay electrolytes.
An Investigation on Gel-State Electrolytes for Solar Cells Sensitized with β-Substituted Porphyrinic Dyes

February 2023

·

59 Reads

·

1 Citation

Processes

The presence of a liquid electrolyte in dye-sensitized solar cells (DSSCs) is known to limit the time stability of these devices due to leakage and evaporation phenomena. To overcome this issue, gel-state electrolytes may represent a good solution in order to maintain stability and good performances, albeit at lower costs. In the present work, two different kinds of gel-electrolytes, based on poly (methyl methacrylate) (PMMA) and nanoclay agents, were investigated in DSSC-devices sensitized using β-substituted Zn-porphyrins (namely ZnPC4 and ZnPC12) with enveloping alkoxy chains of different lengths, able to produce a coverage of the photoanode surface. The highest power conversion efficiency (PCE) values equal to 1.06 ± 0.04% and 1.55 ± 0.26% were obtained for ZnPC12 (with longer alkoxy chains) with PMMA- and nanoclay-based electrolytes respectively. The properties of the photoanode/electrolyte interface as well as the influence of the gelling agents on the final properties of the obtained devices were thoroughly characterized.



Ad

Citations (63)


... Indeed, alginate was used as a coating for fruits and vegetables, emulsifying agent in the food industry, injectable hydrogel for tissue engineering, wound dressing system in biomedical sciences, as a drug and protein delivery system in pharmaceuticals and as an eco-friendly surface cleaning tool in the field of cultural heritage. [3][4][5][6][7][8] Numerous studies highlighted the prompt gel-forming properties of alginate with divalent cations (Ca 2 + , Sr 2 + , Ba 2 + , etc.), in particular with calcium ions, which form an "egg-box" 3D network. [9][10][11] This process does not require harsh conditions or potentially toxic reagents; in this regard, it has the greatest application as an excipient in drug delivery, which allows gradual loading and release of the drug through the process of diffusion and erosion. ...

Reference:

Chemically Crosslinked Alginate Hydrogel with Polyaziridine: Effects on Physicochemical Properties and Promising Applications
Retentive bio-based chemical gel for removing glues from water-sensitive wooden artworks

Journal of Cultural Heritage

... However, these processes represent a delicate operation because they may irreversibly compromise the artefact if it is not correctly performed. [31][32][33] Therefore, the cleaning process must be safe for the artefact, ensuring a controlled action and typically, hydrogel limits water or solvent spread on the artefact's surface. Here, we used CA-CHEM gel to selectively detach a paper label from the wood and remove the glue residue without risking damage to the label or the underlying wooden surface with excessive water diffusion. ...

Removing Aged Polymer Coatings from Porous Stone Surfaces Using the Gel Cleaning Method

Coatings

... Remedial conservation focuses on treating objects that have already suffered damage or deterioration. In contrast, preventive conservation encompasses a proactive strategy aimed at preventing future damage and ensuring the longevity of cultural heritage items [2]. Water is one of the dominant factors in weathering processes, acting as a catalyst for the degradation of heritage materials [3-6]. ...

Recent Advances in the Application of Metal Oxide Nanomaterials for the Conservation of Stone Artefacts, Ecotoxicological Impact and Preventive Measures

Coatings

... A limited number of fragments for micro-invasive analysis were sampled by an expert restorer, where micro-cracks or already partially detached parts were recognized. According to the literature, the above-mentioned techniques have been proven to be successful in providing information about the materials [1,3,12,14,23,24] and creating a list of possible pigments used by the artist in the different layers [25][26][27]. ...

Analytical investigations on polychrome artworks from the wooden ceiling of ex-Ospedale San Matteo in Pavia

... During the 16th to the mid-18th centuries, the violin-making industry in Cremona, Italy, flourished unprecedentedly [1]. The proliferation of talented violin luthiers included three master violin makers-Nicola Amati, Antonio Stradivari, and Giuseppe Guarneriwhose violins, despite being several centuries old, still retained their beautiful appearances and excellent acoustic properties [2]. ...

Stradivari’s Varnish Revisited: Feature Improvements Using Chemical Modification

Polymers

... However, these processes represent a delicate operation because they may irreversibly compromise the artefact if it is not correctly performed. [31][32][33] Therefore, the cleaning process must be safe for the artefact, ensuring a controlled action and typically, hydrogel limits water or solvent spread on the artefact's surface. Here, we used CA-CHEM gel to selectively detach a paper label from the wood and remove the glue residue without risking damage to the label or the underlying wooden surface with excessive water diffusion. ...

Nanostructured Emulsions as Smart Cleaning Materials for Removing Aged Polymer Coatings from Stone Substrates

Sustainability

... This standardization was created for the testing of coatings on metal c Clearly, when applying the protective layer to real historical objects, the sample p tion process is dependent on the condition and stability of the artifact [12]. Schematic showing the stages in the lifecycle of a coating. ...

Heritage Conservation and Restoration: Surface Characterization, Cleaning and Treatments

Coatings

... They were introduced to the field of cultural heritage conservation by Richard Wolbers in the mid-1980s [ 11 , 12 ]. Since then, their use has become increasingly common [13][14][15][16]. ...

Biopolymer Gels as a Cleaning System for Differently Featured Wooden Surfaces

Polymers

... This book presents a collection of manuscripts from cutting-edge academic researchers and consists of the following: (i) one review paper regarding fractographic, metallographic and chemical analyses as key tools for improving the interpretation of damage in historical copper and silver alloys [1]; (ii) six experimental research papers focused on the chemical and metallurgical characterization of ancient artifacts such as ceramic casting molds, Nuragic bronze objects, Renaissance swords, Japanese metallic threads and an emblematic copper-based alloy monument [2][3][4][5][6][7]; (iii) two research articles on the use of oxygen depletion testing for quantitatively measuring the deterioration of historical metals and on the employment of different portable/transportable devices to assess the effects of the bronze disease phenomenon [8,9]; (iv) one experimental research paper that aims to determine the optimal application conditions of a new multifunctional coating containing Ag-doped TiO 2 nanoparticles, when used as a possible protective agent for sandstone [10]. ...

Silver-Doped TiO2-PDMS Nanocomposite as a Possible Coating for the Preservation of Serena Stone: Searching for Optimal Application Conditions

Heritage

... Another reason for the increased susceptibility of the instruments to dezincification could be the alloy composition. Historical brass instruments contain a variety of impurities, including lead, tin, zinc, iron, nickel, arsenic, antimony, and silver [25][26][27][28]. In contrast to today's brass alloys of the highest purity, these historic brass alloys rarely show signs of dezincification. ...

X-rays investigations for the characterization of two 17th century brass instruments from Nuremberg

ACTA IMEKO