Thermal, Optical, and Static/Dynamic Mechanical Properties of Linear-core Crosslinked Star Polymer Blends

Core crosslinked star (CCS) polymers ae synthesized and blended with linear polymers. Constrained mobility is revealed by an increase in modulus and strength with CCS polymer concentration, while creep deformation decreases and permanent strain increases. Storage modulus, loss modulus, and glass transition temperature increase with CCS polymer concentration due to miscibility and linear‐CCS polymer “arm” interactions. Master curves shift to lower frequencies with blends that experience segmental relaxation across a broader time scale due to a range of molecular environments from linear to maximum constraints in the vicinity of the crosslinked cores. Fragility and apparent activation energy increase with CCS polymer content, while fractional free volume and volume expansion decrease. Blends of linear and core crosslinked star (CCS) polymers are prepared and the thermal, mechanical and optical properties are characterized. CCS polymers behave as physical crosslinks, restricting segmental motions of linear matrix chains. The time‐temperature superposition is successfully used to construct master curves from which the dynamic fragility and apparent activation energy are calculated.