Sustainable Pressure-Sensitive Adhesives

Pressure-sensitive adhesives (PSAs) are materials that quickly form bonds of measureable strength under light pressure. Triblock copolymers of an ABA architecture are commonly used for PSAs where “A” is typically a glassy block while “B” is a rubbery block at room temperature. Unfavorable enthalpic interactions lead to incompatibility of the blocks, causing them to microphase separate into distinct glassy and rubbery domains. This results in a soft yet elastic material since the glassy blocks act as physical crosslinks for the rubbery midblock.

Our objective was to create a sustainable and cost-effective PSA composed of poly(lactide) (PLA) and poly(β-methyl-δ-valerolactone) (PMVL) blocks. We used a resin tackifier with a low glass-transition temperature to lower the elastic modulus of the triblock copolymer, and tested the miscibility of the tackifier in the PMVL using differential scanning calorimetry (DSC). Rheology was used to probe the linear viscoelastic behavior of five samples with tackifier of varying weight percents, and DSC was used to characterize the glass-transition temperatures. We tested the adhesive properties of three samples using a probe-tack test.  Future work will entail characterizing adhesiveness with additional experiments including peel and shear tests.