hard-segment phase domain

Phase domain of microscopic or smaller size, usually in a block, graft, or segmented copolymer, comprising essentially those segments of the polymer that are rigid and capable of forming strong intermolecular interactions.

Note:

Hard-segment phase domains are typically of $2$ – $15 nm$ linear size.

Source:

PAC, 2004, 76, 1985 (Definition of terms related to polymer blends, composites, and multiphase polymeric materials (IUPAC Recommendations 2004)) on page 2002