Structural factors of benzylated glucopyranans for shear-induced adhesion

Abstract

We have prepared benzylated glucopyranans and evaluated the structural effects on the adhesion capacity. It was found that 97%-benzylated (1→2)-glucopyranan exhibited a unique shear-induced adhesion. The effects of structural factors on the adhesion behaviors are discussed through systematic adhesion tests, differential scanning calorimetry, theoretical models, and IR spectroscopy.

Fig. 1. (a) Structures of Glcp-(1-4) and (b) Glcp-(1-2) and (c) the plausible structure of the kinetically stabilized elongated chain of adhesive Glcp-(1-2)-X.

Fig. 2. (a) Adhesion testing geometry to measure S_Adh, (b) a photograph of the macroscopic fiber formation of Glcp-(1-2)-97, and (c) the dependence of S_Adh on the benzylation ratio. Bars are average values from three samples. The relative standard deviations (%RSD) are 0.04% for Glcp-(1-2)-97, 3.9% for Glcp-(1-2)-80, 24% for Glcp-(1-2)-0, and 23% for Glcp-(1-4)-95.

Scheme 1. Synthesis of Glcp-(1-2)-based adhesives. Glcp-(1-2) with X% benzylation is abbreviated as Glcp-(1-2)-X.

Fig. 3. (a) Dependence of S_Adh on the number of cycles by the repeated lap-shear tests of Glcp-(1-2)-X using the same sample (v: 10 mm min⁻¹), (b) dependence of the S_Adh value of Glcp-(1-2)-97 on v, and (c) the proportional relationship of S_Adh to G^0.55. Lines are to guide the eyes.

Fig. 4. Partial IR spectra of Glcp-(1-2)-97, Glcp-(1-2)-80, and Glcp-(1-4)-95.