Comparison of Trimethylsilyl Cellulose-Stabilized Carbonate and Hydroxide Nanoparticles for Deacidification and Strengthening of Cellulose-Based Cultural Heritage

• Published in: ACS omega 2020-11, Vol.5 (45), p.29243-29256
• Main Authors: Amornkitbamrung, Lunjakorn, Bračič, Doris, Bračič, Matej, Hribernik, Silvo, Malešič, Jasna, Hirn, Ulrich, Vesel, Alenka, Kleinschek, Karin Stana, Kargl, Rupert, Mohan, Tamilselvan
• Format: Article
• Language: English
• ISSN: 2470-1343; 2470-1343
• DOI: 10.1021/acsomega.0c03997

Herein, colloidal dispersions of alkaline nanoparticles (NPs: CaCO3 and Mg­(OH)2) are stabilized by trimethylsilyl cellulose (TMSC) in hexamethyldisiloxane and employed to treat historical wood pulp paper by an effortless dip-coating technique. Both alkaline NPs exhibit high stability and no size and shape changes upon stabilization with the polymer, as shown by UV–vis spectroscopy and transmission electron microscopy. The long-term effect of NP/TMSC coatings is investigated in detail using accelerated aging. The results from the pH-test and back-titration of coated papers show a complete acid neutralization (pH ∼ 7.4) and introduction of adequate alkaline reserve even after prolonged accelerated aging. Scanning electron microscopy–energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and infrared and water contact angle measurements showed the introduction of a thin and smooth hydrophobic NP/TMSC coating on the paper fibers. Acid-catalyzed desilylation of TMSC was observed by declining C-Si infrared absorbance peaks upon aging. The CaCO3 coatings are superior to Mg­(OH)2 with respect to a reduced yellowing and lower cellulose degradation upon aging as shown by colorimetric measurements and degree of polymerization analysis. The tensile strength and folding endurance of coated and aged papers are improved to 200–300 and 50–70% as illustrated by tensile strength and double folding endurance measurements.