Pressure sensitive adhesive property modification using cellulose nanocrystals

The impact of cellulose nanocrystals (CNCs) as a property modifier for pressure sensitive adhesives (PSAs) was investigated. Stable CNC/poly(n-butyl acrylate-co-methyl methacrylate) latex nanocomposites with different CNC loadings ranging from 0.25 to 1 wt% (based on monomer weight) were synthesized by both an in situ seeded semi-batch polymerization and a blending technique. The PSA films obtained from both techniques demonstrated a concurrent enhancement of shear strength, tack, and peel strength with increasing CNC content. However, the performance enhancement for the PSAs prepared via the in situ technique was substantially greater: increases of up to 3.8x for tack, 6x for peel strength and 20x for shear strength for the in situ technique compared to increases of up to 2.4x for tack, 1.5x for peel strength and 6.4x for shear strength for the blending technique. The difference in mechanical performance of the CNC/PSA films synthesized via the in situ technique vs. blending was a result of better interaction of CNCs with the polymer matrix during both latex synthesis and film formation.