Graft Polymerization of Polyacrylonitrile or Poly(methyl methacrylate) onto Polyurethane for the Improvement of Mechanical Properties and Water Vapor Permeability

Polyurethane was graft‐polymerized with poly(acrylonitrile) or poly(methylmethacrylate) to form the urethane‐acrylate polymers that demonstrated a significant improvement in tensile strength and the better low‐temperature flexibility. The water permeability was also increased if poly(methylmetacrylate) was grafted. Polyacrylonitrile (PAN) or poly(methyl methacrylate) (PMMA) was graft‐polymerized onto polyurethane (PU) to form the urethane‐acrylate polymers grafted with PAN (UA series) or PMMA (UM series). With an increase in the acryl content, the T m, ΔH m , and T g did not significantly change for the UA and UM series. The tensile strengths of the UA and UM series increased with the acryl content, whereas those of the control PUs did not. The breaking strain of the UA and UM series, and control PUs remained the same with the increase in the acryl content. The shape recovery and shape retention of the UA and UM series remained high after four repeated tests. The UA and UM series demonstrated better low‐temperature flexibility and water permeability than the unmodified PU.