If you are looking for a PDF of his work, you are likely seeking one of two foundational texts:
The Physics of Everyday Life: Exploring Masao Doi's Soft Matter Physics soft matter physics masao doi pdf
When subjected to high stress, these materials often exhibit complex, non-linear behavior rather than simple, linear elasticity. If you are looking for a PDF of
Interface Science: How surface tension and surfactants govern the behavior of foams and emulsions. However, as the 21st century progressed, Doi recognized
Before Soft Matter Physics , Doi wrote Introduction to Polymer Physics (Oxford, 1996), which remains a gold standard for its concise, equation-driven approach. However, as the 21st century progressed, Doi recognized that polymers were just one piece of a larger puzzle.
Masao Doi's Soft Matter Physics (2013) is a foundational graduate-level text designed to provide a cohesive physical basis for understanding materials that behave as something between solids and liquids.