Reološke lastnosti vodnih suspenzij nanofibrilirane celuloze

Serafimoski, Stefan (author), Šebenik, Urška (mentor)

Z nenehnim razvojem biokompatibilnih, biorazgradljivih in nestrupenih materialov za hidrogele se je njihova uporaba na področju medicine in farmacije močno razširila. Zaradi pomembnosti teh materialov in njihovih visokih stroškov pridobivanja so potrebne metode karakterizacije, ki porabijo manj materiala za vzorce in so nedestruktivne za vzorca. Pomemben sklop lastnosti, ki so neposredno povezane z njihovo uporabo in vzdrževanjem v organizmu, so reološke lastnosti teh materialov. V svojem magistrskem delu sem preučeval vplivi staranja gela in masne vsebnosti dispergirane faze v nizu suspenzij na bazi nanofibrilirane celuloze. Vplivi sem preučeval s primerjavo dvema metodama – reometra, ki lahko karakterizira vzorce v volumnu mililitrov, in optične pincete, ki, kot mikroreološka metoda karakterizacije lahko karakterizira vzorce z volumnom v mikrolitrih, ali celo nanolitrih. Na podlagi poskusov in matematičnega modeliranja eksperimentalnih podatkov sem ugotovil, da staranje sistemov in masni delež dispergirane faze vplivata na reološke lastnosti sistemov. Poleg tega sem ugotovil, da rezultati obeh metod niso primerljivi med seboj v istem časovnem obdobju. Ugotovil pa sem tudi, da mikroreološke meritve z optično pinceto zagotavljajo dopolnilne informacije o reološkem in viskoelastičnem obnašanju heterogenih sistemov, ki so povezane s spremembami v mikrostrukturi suspenzije, in sicer na drugačni časovni skali, ki je ni mogoče zabeležiti z uporabo reometra za karakterizacijo sistemov.

• Language: Slovenian
• Keywords: hidrogel, nanofibrilirana celuloza, reologija, mikroreologija, optična pinceta
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2022
• PID: 20.500.12556/RUL-140169
• COBISS.SI-ID: 130973955
• Publication date in RUL: 12.09.2022

Secondary language

• Language: English
• Title: Rheological properties of nanofibrilated cellulose suspensions

Abstract

With the continuous advancement of biocompatible, biodegradable and non- toxic materials for hydrogels, their usage has greatly expanded in the fields of medicine and pharmaceuticals. The importance of those materials, combined with their high sourcing cost, invokes the need for characterization methods which consume less material for samples and are non-destructive to the sample. Meanwhile, an important set of properties that are directly connected to their application and maintenance in an organism are the rheological properties of such materials. In my master’s thesis, I studied the effects of ageing and weight percentage of the dispersed phase in a set of nanofibrilated cellulose suspensions, using a comparison of two methods – a rheometer, which measures the material in bulk quantities (in the range of milliliters), and optical tweezers, which is a method of microrheological measurement (in the range of micro and nanoliters). Based on the experiments and the fitting of the experimental data, I found out that the ageing of the systems and the weight percentage of the dispersed phase has an influence on the rheological properties of the systems. Further, I have found that the results from both methods were not comparable on the same timescale. However, I have also found out that microrheological measurements using optical tweezers provide complementary information on the rheological and viscoelastic behavior of heterogeneous systems related to changes in the suspension microstructure, on a different timescale, which is not possible to be recorded by using a rheometer to characterize the systems.

• Keywords: hydrogel, nanofibrilated cellulose, rheology, microrheology, optical tweezers