Unveiling the role of ultrasonication variables on lignin-coated cellulose nanocrystal dispersion in polyethylene oxide-based suspension and resulting morphology and mechanical properties

Authors: RAEISI, AMIRMOHAMMAD - Montana State University; ARA, ISMAT - Montana State University; BAJWA, DILPREET - Montana State University; Holt, Gregory

Submitted to: ACS Applied Bio Materials
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2025
Publication Date: 2/26/2025
Citation: Raeisi, A., Ara, I., Bajwa, D., Holt, G.A. 2025. Unveiling the role of ultrasonication variables on lignin-coated cellulose nanocrystal dispersion in polyethylene oxide-based suspension and resulting morphology and mechanical properties. ACS Applied Bio Materials. 10(9). https://doi.org/10.1021/acsomega.4c06854?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as.
DOI: https://doi.org/10.1021/acsomega.4c06854?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as

Interpretive Summary: Cellulose nanocrystals, also known as CNC's, have gained interest due to their ability to biodegrade, abundance, and outstanding properties. One of the challenges of using CNC's in the manufacture of bio-based composite materials is their unwillingness to disperse uniformly in polymers. This study looked at using ultrasonics to disperse lignin-coated CNC (L-CNC) at two different levels (50% and 100%) for time frames of 3, 6, and 9 minutes to determine if the process improved the uniformity of the CNC's in the polymer. Results showed the 100% amplitude at 9 minutes resulted in a 300% improvement in dispersion compared to the other treatments. This study was the first step in determining optimal processing parameters for improving L-CNC dispersion and enhancing performance of CNC composite materials.

Technical Abstract: The biodegradability, abundant availability, and outstanding intrinsic properties of cellulose nanocrystals (CNCs) have made them a suitable candidate for functionalizing polymer materials. Lignin is another abundant material in nature, which is a remarkable UV blocking agent. Hence, their combination can produce material with multifunctional properties. However, the self-assembling ability of CNCs can make it challenging to develop their well-dispersed suspension in polymer-based aqueous solutions. However, it is essential to identify the effective set of ultrasonication parameters to obtain the desired particle size and its morphology. This study investigated the role of ultrasonication treatment in dispersing lignin-coated CNCs (L-CNCs) within the water-soluble polyethylene oxide (PEO). The aqueous suspensions were prepared by dispersing of L-CNC in 1 wt.% of PEO solution where varying ultrasonication times (3, 6, and 9 minutes) and different amplitudes (50 and 100%) were employed. The morphology, particle size, and dispersion of L-CNCs were analyzed using zeta potential analysis, contact angle, and scanning electron microscopy. Additionally, the mechanical and physical properties were assessed through dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The results indicated that an increase in sonication time and amplitude could significantly influence the dispersion of L-CNCs within the PEO polymer matrix, as evidenced by the increase in zeta potential. Increased sonication time and amplitude improved dispersion and reduced the size and number of agglomerations. Ultrasonication at 100% amplitude for 9 minutes resulted in a 300% and more increase in the storage modulus of composite films. The comprehensive results obtained from this study aim to enhance our understanding of optimal ultrasonication parameters, contributing to improved L-CNC dispersion and enhanced performance of the composite material.