Pressure sensitive adhesive property modification using cellulose nanocrystals

Nanocellulose as a natural source for groundbreaking applications in materials science: Today’s state

“…Paints, adhesives, coatings, and composites -Again, the stabilizing and reinforcing abilities of CNCs promise to enhance latexbased applications such as paints, adhesives, and coatings and make their production processes more environmentally friendly (e.g., by replacing solvent-based polymerization methods and/or components like synthetic surfactants). Simply mixing CNCs and synthetic latexes (or in situ polymerization) can dramatically improve properties such as mechanical strength [389], shear/peel strength and tack [323,390] and 3M was the first company to patent the use of CNCs in pressure sensitive adhesives (PSAs) Fig. 16 highlights the improvement in all performance metrics for a butyl acrylate/methyl methacrylate latex-based PSA with CNCs: increasing the CNC loading increases shear, tack and peel and adhesives synthesized in the presence of CNCs outperform the latex/CNC blends, possibly due to crosslinking and improved film formation [390].…”

A sequential design approach for in situ incorporation of cellulose nanocrystals in emulsion-based pressure sensitive adhesives

“…The in situ incorporation of up to 1 phm CNC (phm: parts per hundred parts monomer by mass) in emulsion polymerization of poly(n-butyl acrylate-methyl methacrylate) (BA/MMA) resulted in significant and simultaneous improvement of all three PSA characteristics (Dastjerdi et al 2018). This groundbreaking finding solves a long-time conundrum in PSA property modification, which originates from a polymer's viscoelastic behaviour, and the fact that microstructural modification usually only improves one aspect of such behaviour at a time (Jovanović and Dubé 2005;González et al 2006;Ren and Dubé 2017).…”

“…In situ addition of CNCs elevated the hydrophilicity of the PSAs and therefore, their work of adhesion, which resulted in better tack and to some degree peel strength. At the same time, higher elasticity of the CNC-incorporated PSAs and their enhanced shear strength was attributed to stronger cohesive forces because of possible crosslinking or hydrogen bonding (Dastjerdi et al 2018). Further studies showed that the use of a hydrophobic monomer, i.e., 2-ethyl hexyl acrylate compared to a more hydrophilic one, i.e., isobutyl acrylate, negatively affected the dispersion of CNCs in the final PSA film (Ouzas et al 2018a).…”

Synthesis of latex stabilized by unmodified cellulose nanocrystals: the effect of monomers on particle size

“…54 CNCs have been incorporated into polymerization processes to design nanocomposite latexes in order to improve the mechanical properties of the polymer. 55 In the early studies, CNCs were used in combination with surfactants and were anchored at the interface either by coupling agents [56][57][58] or by electrostatic interactions with surfactants. 59,60 CNCs were therefore not directly involved in the stabilization of monomer droplets or latex particles.…”