No, work is not done during thermal expansion itself. Thermal expansion refers to the increase in size or volume of a substance in response to a temperature change. When a substance expands or contracts due to temperature variations, no external force is being applied to cause the expansion. Therefore, no work is done in the thermodynamic sense.
Work, in thermodynamics, is defined as the energy transfer that occurs when a force is applied to move an object through a displacement. It involves the application of an external force over a distance. In the case of thermal expansion, the expansion occurs spontaneously without any external force acting on the substance, so no work is performed.
However, it's worth noting that thermal expansion can result in changes in pressure or the displacement of objects that are restrained or connected to the expanding material. In such cases, work can be done by or on those objects due to the forces involved. But the expansion itself, without any external forces or restraints, does not involve work.