Cellulose nanocrystals as consolidant of paper artefacts. A new concept of conservation of Cultural Heritage

A new work from the NanoLeaves Lab in collaboration with colleagues from the University of Rome Tor Vergata, from ENEA – Italian National Agency for New Technologies, Energy and Sustainable Economic Development and from the University of Rome La Sapienza, focuses on the use of sustainable CNCs in paper conservation. The proposed approach is benign for the health of restorers, as CNCs are non-toxic and they are dispensed from water.

CNCs are transparent, mechanically and thermally stable, and act as a protective treatment for paper fibers. Furthermore, we demonstrated for the first time their straightforward removal from paper by hydrogel cleaning.

Simple? Yes. The treatment is so promising that we applied it to the pages of a book dated 1738 from a private collection, with remarkable consolidation results.

The research is presently published on ACS Applied Materials and Interfaces as an ASAP paper in open access form.

Enjoy this new stunning research!

Figure 1
Graphical Abstract of the paper “Toward a Reversible Consolidation of Paper Materials Using Cellulose Nanocrystals”, published in ACS Applied Materials and Interfaces in 2021.

Copyrights of this article belong to Alessandra Operamolla. All rights reserved.

New papers published on functionalized thiophene – arylene based organic semiconductors

During these first months of 2021 I have published two papers concerning my previous research activities started at the University of Bari Aldo Moro.

Among my specializations, I am expert in the synthesis and characterization of conjugated materials based on arylenethienylene structures.

The first of these studies describes the preparation and characterization of diketopyrrolopyrrole (DPP) and thiophene -based oligomers, decorated with -SAc groups. This work is the natural evolution of my PhD thesis, that was centered on the preparation of thiol oligoarylenes for molecular electronics. During my PhD studies, the group of Alan Heeger published a paper on Nature Materials describing how aliphatic thiols additives were able to improve the performances of polymeric bulk-heterojunction solar cells. Later on, it was explained that the aliphatic thiol was able to dissolve the fullerene counterpart. This was the period in which I decided to synthesize thiol decorated oligo- and polythiophenes and study their blend forming properties mixing them with PCBM. It took a long time to study these systems, as they were introduced in BHJ solar cells as third components, and understanding the behavior of ternary blends is not easy. Resolutive was my visit at the Imperial College in 2015, in the group of Prof. Natalie Stingelin, were I performed in collaboration with her group differential scanning calorimetry studies on the melting properties of our blends. This was truly helpful to understand the physical chemistry going on there. The result was a paper full of experimental evidences, published in Chemistry of Materials in 2018.

Graphical abstract of the article “Designing Small Molecules as Ternary Energy-Cascade Additives for Polymer:Fullerene Solar Cell Blends” by A. Punzi, A. Operamolla, O. Hassan Omar, F. Brunetti, A. D. Scaccabarozzi, G. M. Farinola and N. Stingelin, published in Chem. Mater. 2018, doi: 10.1021/acs.chemmater.8b00675

This year, we have published the natural progress of that paper. In the aim of preparing novel additives for BHJ solar cells, we observed that the S-Acyl group decorating DPP-oligomers was able to induce a huge red-shift of absorbed solid-state wavelength, which correspond to enhanced formation of J-aggregates. This behavior is peculiar, and can be replicated also in solid state nanoparticles. The results were interesting and deserved a publication in the journal RSC Advances, as a Gold Open Access paper.

Graphical abstract: Peripherical thioester functionalization induces J-aggregation in bithiophene-DPP films and nanoparticles
Graphical abstract of the article “Peripherical thioester functionalization induces J-aggregation in bithiophene-DPP films and nanoparticles” by A. Punzi, D. Blasi, A. Operamolla, R. Comparelli, G. Palazzo and G. M. Farinola, published in RSC Adv. 2021, doi: 10.1039/D1RA01253C

The second paper is pertinent to another class of thiophenearylene – based materials, on which we used the alkoxy substituents to bind enantiomerically pure small biomolecules. More specifically, we are able to decorate the conjugated framework with D-glucopyranose units via beta-glycosides and with tBOC-protected L-phenylalanine via ester bond formation. These materials and their films can be studied by electronic circular dicroism technique (ECD) to get useful insides on the mechanism of their solid-state aggregation. This study is published in the RSC journal New Journal of Chemistry.

Graphical abstract: Impact of chirality on the aggregation modes of l-phenylalanine- and d-glucose-decorated phenylene–thiophene oligomers
Graphical abstract of the article “Impact of chirality on the aggregation modes of l-phenylalanine- and d-glucose-decorated phenylene–thiophene oligomers” by O. Hassan Omar, M. Falcone, A. Operamolla and G. Albano, published in New J. Chem. 2021, doi: 10.1039/D1NJ02125G

Copyrights of this article belong to Alessandra Operamolla. All rights reserved.

New work from the NanoLeaves lab: pyrene-modified nanocrystals

The reductive amination reaction is an interesting tool to achieve one terminus functionalization of cellulose nanocrystals. Since at NanoLeaves laboratory we are interested in novel applications of CNCs, we have used pyrene luminescence to understand if the new functionality introduced on CNCs may interact preferentially with some metal cations.

In our work we compare the behavior of reductively aminated CNCs deriving from sulfuric acid hydrolysis or hydrochloric acid hydrolysis (that we named neutral CNC, N_CNC). Pyrene luminescence in water is used as a probe to understand if some selective or preferential interaction with metal cation achieves involving the pyrene portion of the nanocrystals.

With this paper, we demonstrate how we manipulate N_CNC in suspension and how we can achieve selective interaction with cations in water, discarding other chemically or optically interfering phenomena.

This is a fundamental study on the usefulness of the reductive amination reaction performed on nanocellulose. This topic is presently object of research at the NanoLeaves Lab, as usual with the aim of achieving unconventional applications of nanocellulose.

Go to the paper, published in Molecules, 2021

Copyrights of this article belong to Alessandra Operamolla. All rights reserved.

Call for papers: “Sustainable Materials and Processes for Organic Electronics” – Sustainability

Dr. Mariacecilia Pasini, Prof. Varun Vhora and Prof. Alessandra Operamolla are the Guest Editors of the special Issue entitled “Sustainable Materials and Processes for Organic Electronics” proposed for the journal Sustainability (Publisher MDPI) with deadline October 21st 2021.

The special issue will put chief attention to sustainable materials, processes, energy production and devices linked to the world of thin film organic and non organic electronics. The issue represents a nice opportunity to collect contributions by researchers from all over the world, showing the current trends of the topic.

If you wish to receive more information about the process and the special issue, please contact the Guest Editors at their institutional addresses, visit the website or download the special issue flyer.

Our new article published on Polymers – MDPI investigates the electrochemical performance of fullerene – CNC hybrid films

A new paper, released in 2021, collects our results on the electrochemical and physico-chemical investigation performed on Langmuir-Shaefer co-deposited films of sulfated cellulose nanocrystals and fulleropyrrolidines (FP). The work is done in collaboration between the University of Pisa, the University of Salento and the University of Trieste, and extends the results and the comprehension on these exciting new hybrid films, previously presented for the first time on the journal Carbon in 2020 by the same group of investigators.

The new paper sheds more light on the nature of the spontaneous interaction between CNCs and FPs, by describing competitive self-assembling experiments in the presence of a solfonated porphirin, the TPPS4 material. Moreover, anodic photocurrents are explored, pointing at the clear contribution of cellulose to current generation.

Below, the graphical abstract of the new paper. Clicking on the picture, you will be re-addressed to the journal page where you will be able to download our paper free of charge.

Felicitations to Prof. Sabu Thomas for his birth anniversary

Last November 21st 2020, I was invited by the Alumni group of Prof. Sabu Thomas from Mahatma Gandhi University (MGU), Kottayam, Kerala, India to participate in a global party to celebrate the brilliant career of Prof. Thomas and his 60th anniversary.

Prof. Sabu Thomas is presently Vice Cancellor of the Mahatma Gandhi University in India and is a researcher whose achievements have had and will have a great impact on the scientific community, especially in the fields of materials and polymers chemistry and of nanotechnology. As one of the most globally cited researchers in the field, Prof. Thomas has also been recently listed among the top 2% scientists by Stanford University, USA.

Prof. Thomas has successfully completed 33 years of research activity in the Mahatma Gandhi University, giving a precious contribution to its successful growth and educating numerous young researchers.

I would like to thank the Alumni group for inviting me in this beautiful virtual meeting and congratulate officially with Prof. Thomas for his remarkable achievements as an investigator and research leader.

Our contribution in the book “Nanocellulose Based Composites for Electronics” (Elsevier, 2020)

A contribution from the NanoLeaves Lab has been included as Chapter 3, entitled “Nanocellulosed-base functional paper” in the book “Nanocellulose Based Composites for Electronics”, published on October 9th 2020 by Elsevier.

The book, edited by Prof. Sabu Thomas and Dr. Yasin Beeran Pottathara, “presents recent developments in the synthesis and applications of nanocellulose composites in electronics, highlighting applications in various technologies. Chapters cover new trends and challenges in a wide range of electronic applications and devices. Significant properties, safety, sustainability, and environmental impacts of the electronic devices are included, along with the challenges of using nanocellulose-based composites in electronics. This book is an important reference for materials scientists and engineers configuring and designing processes for the synthesis and device fabrication of nanocellulose composites in electronics.”

Chapter 3, the contribution presented by Rosa Giannelli, Francesco Babudri and Alessandra Operamolla, describes the potentialities of cellulose nanopaper(CNP) prepared from renewable nanocellulose, focusing on the re-engineering of CNP by physical and chemical design to enable hydrophobic and transparent paper, smart sensors, substrates for optoelectronic devices and conductive or luminescent papers.

Roadmap of nanocellulose to the market: expected applications

What are the potentialities of nanocelluloses exploitation? And how far are we from their entrance into the global market? 

Innovative enterprises are already on the market with pilot production of various forms of nanocellulose materials. The following worldwide known companies have already started to produce various forms of nanocellulose, including NFC (nanofibrillated cellulose), MFC (microfibrillated cellulose) and CNC (cellulose nanocrystals): Celluforce, Alberta Innovate, Blue Goose Biorefineries and FPInnovations  (Canada), US Forest Service – Forest Products Laboratory and University of Maine (USA), Melodea Ltd and Innventia AB (Sweden),  Nippon paper, Daicel and Oji Paper (Japan), Borregaard and FPI (Norway), NamiCell and InoFib (France), Stora Enso, VTT and UPM Kymmene Ltd (Finland), JRS and BASF/Zelpho (Germany), Weidmann, EMPA and Omya (Switzerland), CelluComp (UK). 

Research laboratories can provide amounts of nanocellulose lower than 0.1 kg/day, except the pilot plant present at INP–Grenoble, which can produce 2 kg/day. 

In 2015, the worldwide announced (by enterprises and research laboratories) production amount of dry nanocellulose was >1 ton per day for both nanofibrillated cellulose and cellulose nanostructured materials. These values are comprehensive of the production capacities declared by only some of the above cited enterprises; some of them have not declared their effective production capacity, yet. 

The production of nanocellulose from these plants must be increased, in order to satisfy the necessity of lowering production costs, and, in particular, to enable the high volume applications envisaged for the nanocellulose materials. 

In 2014 Dr. J. A. Shatkin et al. published a study, carried out through literature surveys and interviews, to identify the applications of nanocellulose. The study was based on the analysis of ongoing research, state-of-art results, and recoinnassance of the intentions manifested by exploiters and investors. 

This helped to give a list of market areas of implementation for the nanocelluloses, divided as follows: 

High-volume applications These applications will exploit the highest potential volume of nanocellulose and are widely recognised as feasible, because they often hold an intermediate technology readiness level. They include automotive sector, coatings for paper and textile, products for hygiene, paper fillers, building sector.
– Low-volume applications These applications will exploit a lower potential volume of cellulose nanomaterials, but are widely recognised as well as the high-volume applications. They include insulating materials, aerospace materials, paint additives and aerogels.
– Novel and emerging applications These applications are innovative, groundbreaking and recently discovered. Their knowledge is still at the level of proof of concept. They include use of nanocellulose in optoelectronics, photonic films and materials, sensors, cosmetics, water or air filtration, 3D printing, catalysis and so on.

The expected benefits for the society given by the transition from the use of oil-derivatives to nanocellulose products in these sectors will be several: first of all, the implementation of new technologies will sustain the increase of employment and improve the specialization profile of employees, that will be more skilled and better payed.  

Moreover, most of these products will be produced closer to the place where they will be processed into high-added value products and selled; this element, combined to the lightweight quality possessed by nanocellulose, will drastically reduce the costs and environmental impact for raw materials transportation.  

The biodegradability and renewability of cellulose nanomaterials will respond to the concerns about the environmental impact of present technologies and about the progressive deployment of materials resources.  

Last but not least, the substitution of plastic materials with cellulose will contribute to the decrease of CO2 emission in the atmosphere as an effect of the carbon dioxide consumption produced by trees, that would enter into the carbon economy for those products: this outcome will positively reduce the effects on global climate change.  


1 Miller, J.; Nanocellulosetechnology applications, and markets, 2014, TAPPI international conference on nanotechnology for renewable materials, 23–26 June, Vancouver, BC 

2 Shatkin, J. A.; Wegner, T. H.; Bilek, E. M.; Cowie, J.; Market projections of cellulose nanomaterial-enabled products − Part 1: Applications2014, TAPPI Journal, 13, 9-17. 

Copyrights of this article belong to Alessandra Operamolla. All rights reserved.

Open Access Material from the Blog NanoLeaves

Up to date, I have published papers on the topic of nanocellulose and cellulose nanocrystals. My research interested are more in defining innovative applications, from the technological point of view, for nanocelluloses, rather than working on the nanocellulose extraction and production.

Here is a list of open access materials that I have produced so far, also with the collaboration of other excellent Italian researchers!

1. Nanocarta di cellulosa: proprietà e prospettive, by Alessandra Operamolla. A paper in Italian, published by the Italian Chemical Society, now available for free at the following link.

2. SolarLeaf: Celle Solari Organiche Biodegradabili Supportate su Cellulosa” , by Alessandra Operamolla. A summary of the research project SolarLeaf, published in Italian, on pages 73-79 of the book “FutureInResearch – Un volano per l’Innovazione”, oublished by the University of Bari Aldo Moro, available at the following link.

3. “Recent Advances on Renewable and Biodegradable Cellulose Nanopaper Substrates for Transparent Light-Harvesting Devices: Interaction with Humid Environment”, by Alessandra Operamolla, a review published on the International Journal of Photoenergy in 2019, available at the following link.

4. “Improving 2D-organization of fullerene Langmuir-Schäfer thin films by interaction with cellulose nanocrystals”, by Shadi Sawalha, Francesco Milano, Maria Rachele Guascito, Simona Bettini, Livia Giotta,* Alessandra Operamolla,* Tatiana Da Ros, Maurizio Prato, Ludovico Valli, a research article published on Carbon in 2020 (vol. 167, pages 906-917), made available for free via this link until September 5th 2020.

For any other request and curiosity, please contact me!

New paper “Improving 2D-organization of fullerene Langmuir-Schäfer thin films by interaction with cellulose nanocrystals” published on Carbon (Elsevier)

The paper Improving 2D-organization of fullerene Langmuir-Schäfer thin films by interaction with cellulose nanocrystals is the fruit of a collaboration between the Universities of Pisa, Bari, Salento, and Trieste and of the Basque Foundation for Science.

The paper is an in-deep investigation on the ability of sulfated CNCs to assist the two-dimensional organization of fulleropyrrolidines at the air/water interface, leading to hybrid Langmuir-Schäfer films with improved (photo)electrical properties. The CNCs are able to favour the assembly of organized hybrid C60/CNC films with improved photo-electrochemical properties. The favored hydrogen evolution reaction paves the way to the development of more performing C60-based electrochemical devices, able to better exploit the unique properties of carbon nanostructures.

Figure. Graphical abstract of the article Improving 2D-organization of fullerene Langmuir-Schäfer thin films by interaction with cellulose nanocrystals

The final version – containing full bibliographic details – of this paper is now available online.

The following Share Link provides 50 days’ free access to the article. Anyone clicking on this link before September 05, 2020 will be taken directly to the final version of the article on ScienceDirect, which they are welcome to read or download. No sign up, registration or fees are required.

Copyrights of this article belong to Alessandra Operamolla. All rights reserved.