Post by 1dave on Jun 2, 2024 10:58:25 GMT -5
I am curious about gels. They are supposed to be amorphous - without form, but are they? Take a spoon to a bowl of Jello, and it breaks in a chonchoidal fracture with thousands of lines per inch. Perhaps there is organization we are not aware of?
From Wikipedia, the free encyclopedia
A gel is a semi-solid that can have properties ranging from soft and weak to hard and tough.[1][2] Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady state, although the liquid phase may still diffuse through this system.[3]
IUPAC definition for a gel
Gels are mostly liquid by mass, yet they behave like solids because of a three-dimensional cross-linked network within the liquid. It is the cross-linking within the fluid that gives a gel its structure (hardness) and contributes to the adhesive stick (tack). In this way, gels are a dispersion of molecules of a liquid within a solid medium. The word gel was coined by 19th-century Scottish chemist Thomas Graham by clipping from gelatine.[4]
The process of forming a gel is called gelation.
doi:10.1351/goldbook.G02600
IUPAC Compendium of Chemical Terminology Copyright © 2014 IUPAC
gel
Non-fluid colloidal network or polymer network that is expanded throughout its whole
volume by a fluid.
Notes:
1. A gel has a finite, usually rather small, yield stress.
2. A gel can contain:
1. a covalent polymer network, e.g., a network formed by crosslinking polymer
chains or by non-linear polymerization;
2. a polymer network formed through the physical aggregation of polymer chains,
caused by hydrogen bonds, crystallization, helix formation, complexation, etc,
that results in regions of local order acting as the network junction points. The
resulting swollen network may be termed a thermoreversible gel if the regions
of local order are thermally reversible;
3. a polymer network formed through glassy junction points, e.g., one based
on block copolymers. If the junction points are thermally reversible glassy
domains, the resulting swollen network may also be termed a thermoreversible
gel;
4. lamellar structures including mesophases, e.g., soap gels, phospholipids and
clays;
5. particulate disordered structures, e.g., a flocculent precipitate usually
consisting of particles with large geometrical anisotropy, 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.
Source:
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
From Wikipedia, the free encyclopedia
A gel is a semi-solid that can have properties ranging from soft and weak to hard and tough.[1][2] Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady state, although the liquid phase may still diffuse through this system.[3]
IUPAC definition for a gel
Gels are mostly liquid by mass, yet they behave like solids because of a three-dimensional cross-linked network within the liquid. It is the cross-linking within the fluid that gives a gel its structure (hardness) and contributes to the adhesive stick (tack). In this way, gels are a dispersion of molecules of a liquid within a solid medium. The word gel was coined by 19th-century Scottish chemist Thomas Graham by clipping from gelatine.[4]
The process of forming a gel is called gelation.
doi:10.1351/goldbook.G02600
IUPAC Compendium of Chemical Terminology Copyright © 2014 IUPAC
gel
Non-fluid colloidal network or polymer network that is expanded throughout its whole
volume by a fluid.
Notes:
1. A gel has a finite, usually rather small, yield stress.
2. A gel can contain:
1. a covalent polymer network, e.g., a network formed by crosslinking polymer
chains or by non-linear polymerization;
2. a polymer network formed through the physical aggregation of polymer chains,
caused by hydrogen bonds, crystallization, helix formation, complexation, etc,
that results in regions of local order acting as the network junction points. The
resulting swollen network may be termed a thermoreversible gel if the regions
of local order are thermally reversible;
3. a polymer network formed through glassy junction points, e.g., one based
on block copolymers. If the junction points are thermally reversible glassy
domains, the resulting swollen network may also be termed a thermoreversible
gel;
4. lamellar structures including mesophases, e.g., soap gels, phospholipids and
clays;
5. particulate disordered structures, e.g., a flocculent precipitate usually
consisting of particles with large geometrical anisotropy, 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.
Source:
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
