The thermal, dynamic mechanical, and dielectric properties of copper-coated lipid tubules incorporated into three polyurethane matrices with varying surface tensions have been examined. The tubules did not affect the glass-transition temperature of the polymer matrices, indicating that the tubule-polymer interactions may not be strong enough to restrict the mobility of polymer chains near the filler surface. The composite's elastic modulus can also be adequately modeled using the Nielsen equation. In addition, the real part of the permittivity for the composites increased monotonically over the tubule concentration range. All samples had a small imaginary part of the permittivity, indicating the tubule concentrations were below the percolation threshold concentration. Also, the three types of matrices had comparable permittivity values at each tubule concentration, suggesting the polymer surface tension did not affect the tubule distribution in the composite. (C) 2003 Wiley Periodicals, Inc.