transcript
- Slide 1
- BindersMolecule type Intermolecular interactions Tempera (egg
yolk)Protein, fat/oil, lecithin Gum arabicpolysaccharide Drying
oils Acrylics Lipids (oils) polymers Mixed (H-bonding, dipole
interactions, hydrophobic interactions) H-bonding hydrophobic
- Slide 2
- A polysaccharide: poly sugar These OH groups bond with water
Gum Arabic: A polysaccharide: poly sugar Gum on acacia tree Gums:
soluble in water; form viscous (mucilinous) "solutions"; of C, H
and O only. Are typically organic carboyhydrate acids as Ca, Mg or
K salts.
- Slide 3
- Drying oils: lipids 5 Views of Linoleic Acid = C 18 H 32 O 2 2
unsaturated bonds (2 double bonds) Carbons only Carbons and
Hydrogens Note bend: due to Double bond
- Slide 4
- Other drying oils: Linoleic Acid = C 18 H 32 O 2 : 2
unsaturated bonds (2 double bonds) Oleic = C 18 H 34 O 2 Linolenic
= C 18 H 30 O 2 1 unsaturated bonds (1 double bonds) 3 unsaturated
bonds (3 double bonds)
- Slide 5
- The drying reaction: Drying is not just evaporation of solvent
(like fresco drying wasn't). Is a chemical reaction: oxidation
(here, addition of O 2 ); Double bonds are reactive (unstable) and
that is where O 2 adds Oxidation by O 2 can be catalyzed by Co, Mn
other metals (siccants)
- Slide 6
- Acrylics: are polymers monomer unit = Acrylic Acid: CH 2 =CHOOH
picture of polymer Methyl Methacrylate: monomer unit CH 2 =C(CH 3
)COOCH 3
- Slide 7
- Tempera (egg yolk): Protein, fat/oil, lecithin Oil / fat
- Slide 8
- Tempera (egg yolk): Protein, fat/oil, lecithin lecithin Fatty
acid
- Slide 9
- Tempera (egg yolk): Protein, fat/oil, lecithin lecithin Fatty
acid Example of protein
- Slide 10
- So whats the bottom line regarding binders? Theyre all BIG
molecules Theyre all organic molecules Theyre most often bio
molecules They bind using Intermolecular Forces