| 초록 |
The adhesion properties of two liquid crystalline polymers (LCPs), octylsulfonylhexylthiomethyl-substituted polyoxyethylene (8S6EO) and hexadecylsulfonylmethyl-substituted polyoxyethylene (16SEO), modified with sulfone groups in side chains was investigated against model pressure sensitive adhesive (PSA) such as acrylic latex. Both 8S6EO and 16SEO form the crystalline phase below the main transition, yielding the dominant coverage of alkyl chains at the free surface and the strong dipole-dipole interactions among sulfone groups in side chains. Therefore, the tack behavior for both of them seemed similar at low temperature, providing poor adhesion with the acrylic PSA due to the screening effect of the dipole-dipole interactions of sulfone groups from LCPs with carbonyl groups in acrylic latex adhesive. In order to create an interface between LCPs and the acrylic latex adhesive, we put silicon wafers on the adhesive surface and then anneal the sample overnight above the main transition where the enthalpic interactions among sulfone groups are shown to break. For 8S6EO, the interfacial adhesion became surprisingly improved, yielding the highly extened fibrillation plateau in stress vs strain plot. The reason for this dramatic change in adhesion property may be due to the dipole-dipole interactions between sulfone groups in LCPs and carbonyl groups in latex adhesive. On the other hand, 16SEO, which we believe has higher screening effect due to the location of sulfone groups closer to the backbone chain, exhibited a gradual change in adhesion even above the main transition. These tack behaviors are also in good agreement with FT-IR data monitoring the vibrational peaks of sulfone groups. |
