intercalation

in polymer chemistry
https://doi.org/10.1351/goldbook.IT07248
Process by which a substance becomes transferred into pre-existing spaces of molecular dimensions in a second substance.
Note:
The term as defined here is specific to polymer science. An alternative definition of 'intercalation' applies in some other fields of chemistry.
Source:
PAC, 2004, 76, 1985. (Definition of terms related to polymer blends, composites, and multiphase polymeric materials (IUPAC Recommendations 2004)) on page 1991 [Terms] [Paper]