Influence of cellulose nanocrystal surface chemistry and dispersion quality on latex nanocomposite stability, film formation and adhesive properties

Abstract

Cellulose nanocrystals (CNCs) are sustainably sourced, non-toxic, high-strength nanoparticles most often derived from wood pulp. The incorporation of CNCs into latexes via in situ semi-batch emulsion polymerization has been shown...

The Effect of Cellulose Nanocrystal Reassembly on Latex-Based Pressure-Sensitive Adhesive Performance

“…Inadequate dispersion of the CNCs in water before addition to the latex can lead to significant CNC-latex particle aggregation, resulting in heterogeneous nanocomposite films, compromised adhesive performance, and possibly latex coagulation. , The redispersion of the dried CNC powder in water has been shown to be necessary for dispersion in the latexin other words, direct addition of the dried powder does not work . A typical protocol in bench scale settings involves sonication of the CNC suspensions before addition to the latex formulation. ,, Given that redispersion and dilution of CNCs in DIW without sonication are normally employed at the industrial scale, we sought to clarify the impact of sonication on PSA performance while comparing the cCNC form used.…”

“…AFM imaging also led to the same conclusion (Figure ). The higher surface charge density observed for never-dried cCNCs compared to the dried-redispersed cCNCs in recent work resulted in superior water stability and a lower degree of aggregation in the never-dried cCNCs. , This difference in surface charge density between the two different cCNC forms in our previous study was attributed to the use of different cCNC batches . However, the dried-redispersed and never-dried cCNCs used in this study were from the same batch and did not demonstrate any differences in surface charge density (0.22 and 0.23 mmol g –1 cCNC for dried-redispersed and never-dried cCNCs, respectively).…”

“…19,34 This difference in surface charge density between the two different cCNC forms in our previous study was attributed to the use of different cCNC batches. 34 However, the dried-redispersed and never-dried cCNCs used in this study were from the same batch and did not demonstrate any differences in surface charge density (0.22 and 0.23 mmol g −1 cCNC for dried-redispersed and neverdried cCNCs, respectively). The surface charge density values reveal the accumulated net charge on a nanoparticle's surface, offering insights into the fundamental source of charge on the shear plane and directly reflecting the nanoparticle's surface chemistry.…”

“…31 A typical protocol in bench scale settings involves sonication of the CNC suspensions before addition to the latex formulation. 31,34,39 Given that redispersion and dilution of CNCs in DIW without sonication are normally employed at the industrial scale, we sought to clarify the impact of sonication on PSA performance while comparing the cCNC form used.…”

“…Furthermore, most studies have used sonication, as an important step in CNC preparation to break up CNC aggregates prior to their addition to the polymer formulation, ,,− but recent work has questioned the need for this processing step. , …”