Tensile Behavior of a Substituted Poly(m‐,p‐phenylene) versus Its Parent Counterpart and Synthesis of Related Polyarylenes

Abstract

In a recent report, a poly(m,p‐phenylene) with acid‐cleavable trialkylsilyl side chains is synthesized by Suzuki polycondensation in a molecular weight of Mw = 300 kDa determined by gel permeation chromatography (GPC). Such a high value suggests this polymer as a potentially attractive material for strong films and fibers both in the presence and absence of the side chains. After confirming these molecular weights by static light scattering, the polymer is processed into thin films for tensile stress measurements. Above the glass transition, thus >180 °C, the material shows an extended plasticity, which is used to obtain elongated samples of draw ratios ranging from 1.5 to 6. The elongated samples show a Young's modulus of up to 5 GPa and a yield strength of 140 MPa. Upon removal of the solubilizing side chains, these values further increase to a Young's modulus of 7.5 GPa in the direction of drawing and a maximum strength of 300 MPa. Motivated by these findings, the scope of this polymer class is broadened by synthesizing two new high molecular weight poly(m,p‐phenylene)s. The structural variation allows to tune the glass transition temperatures between 125 and 240 °C depending on the amount of the meta connected phenylene units. image