Non-fluid @CT07563@ or @P04742@ that is expanded throughout its whole volume by a fluid.
  1. A gel has a finite, usually rather small, @Y06727@.
  2. A gel can contain:
    1. a covalent @P04742@, e.g., a @NT07562@ formed by @CT07136@ polymer chains or by non-linear @P04740@;
    2. a @P04742@ formed through the physical aggregation of polymer chains, caused by hydrogen bonds, @C01434@, @H02769@ formation, complexation, etc, that results in regions of local order acting as the @NT07562@ junction points. The resulting swollen @NT07562@ may be termed a @TT07531@ if the regions of local order are thermally reversible;
    3. a @P04742@ formed through glassy junction points, e.g., one based on @B00682@ copolymers. If the junction points are thermally reversible glassy domains, the resulting swollen @NT07562@ may also be termed a @TT07531@;
    4. lamellar structures including mesophases, e.g., @S05721@ gels, @P04559@ and clays;
    5. particulate disordered structures, e.g., a flocculent precipitate usually consisting of particles with large geometrical @AT06776@, such as in V2O5 gels and globular or fibrillar protein gels.
  3. Corrected from previous definition where the definition is via the property identified in Note 1 (above) rather than of the structural characteristics that describe a gel.
PAC, 2007, 79, 1801. (Definitions of terms relating to the structure and processing of sols, gels, networks, and inorganic-organic hybrid materials (IUPAC Recommendations 2007)) on page 1806 [Terms] [Paper]