Sustainable Triblock Copolymers as Tunable and Degradable Pressure Sensitive Adhesives

Pressure sensitive adhesives (PSAs) are widely used in a variety of applications (e.g., sticky note and packing tape). As for most commercial polymer products, current PSA materials are primarily derived from fossil resources and not readily degradable; this has negative environmental consequences. The design of new PSA materials from sustainable resources that possess competitive adhesion properties and degradability is attractive for addressing sustainability concerns. In this work, we prepared a new aliphatic polyester with a long alkyl substituent, poly(pentadecyl caprolactone) (PPDCL), from cashewnut shell liquid derived lactones by ring opening transesterification polymerization in a controlled fashion. The PPDCL was used as the central block in a symmetric triblock copolymer with poly(lactide) end blocks. A series of ABA triblock copolymers were blended with a renewable tackifier to produce sustainable PSA materials. The resultant PSAs showed competitive adhesion properties with many common commercial adhesives. In addition, the ABA triblock copolymers hydrolytically degraded at 50 °C under acidic conditions suggesting they could be attractive as sustainable and degradable PSA materials.