Both glass ionomer & polycarpoxylate cement contain:
a- Polyacrylic acid.***
b- ZOE powder.
Poly(acrylic acid) (PAA; trade name Carbomer) is a synthetic high-molecular weight polymer of acrylic acid. The IUPAC name is poly(1-carboxyethylene).
They may be homopolymers of acrylic acid, or crosslinked with an allyl ether of pentaerythritol, allyl ether of sucrose, or allyl ether of propylene.
In a water solution at neutral pH, PAA is an anionic polymer, i.e. many of the side chains of PAA will lose their protons and acquire a negative charge.
This makes PAAs polyelectrolytes, with the ability to absorb and retain water and swell to many times their original volume.
Dry PAAs are sold as white, fluffy powders that are frequently used as gels in cosmetic and personal care products.
Their role in cosmetics is to suspend solid in liquids, prevent emulsions from separating and control the consistency in flow of cosmetics.
Carbomer codes (910, 934, 940, 941, and 934P) are an indication of molecular weight and the specific components of the polymer.
For many applications PAAs are used in form of alkali metal or ammonium salts, e.g. sodium polyacrylate.
In the dry powder form, the positively charged sodium ions are bound to the polyacrylate, however in aqueous solutions the sodium ions can dissociate.
Instead of an organized polymer chain, this leads to a swollen gel that can absorb a high amount of water.
Polyacrylic acid is a weak anionic polyelectrolyte, whose degree of ionisation is dependent on solution pH.
In its non-ionised form at low pHs, PAA may associate with various non-ionic polymers (such as polyethylene oxide, poly-N-vinyl pyrrolidone, polyacrylamide, and some cellulose ethers) and form hydrogen-bonded interpolymer complexes In aqueous solutions PAA can also form polycomplexes with oppositely charged polymers (for example, chitosan), surfactants, and drug molecules (for example, streptomycin).
a- Polyacrylic acid.***
b- ZOE powder.
Poly(acrylic acid) (PAA; trade name Carbomer) is a synthetic high-molecular weight polymer of acrylic acid. The IUPAC name is poly(1-carboxyethylene).
They may be homopolymers of acrylic acid, or crosslinked with an allyl ether of pentaerythritol, allyl ether of sucrose, or allyl ether of propylene.
In a water solution at neutral pH, PAA is an anionic polymer, i.e. many of the side chains of PAA will lose their protons and acquire a negative charge.
This makes PAAs polyelectrolytes, with the ability to absorb and retain water and swell to many times their original volume.
Dry PAAs are sold as white, fluffy powders that are frequently used as gels in cosmetic and personal care products.
Their role in cosmetics is to suspend solid in liquids, prevent emulsions from separating and control the consistency in flow of cosmetics.
Carbomer codes (910, 934, 940, 941, and 934P) are an indication of molecular weight and the specific components of the polymer.
For many applications PAAs are used in form of alkali metal or ammonium salts, e.g. sodium polyacrylate.
In the dry powder form, the positively charged sodium ions are bound to the polyacrylate, however in aqueous solutions the sodium ions can dissociate.
Instead of an organized polymer chain, this leads to a swollen gel that can absorb a high amount of water.
Polyacrylic acid is a weak anionic polyelectrolyte, whose degree of ionisation is dependent on solution pH.
In its non-ionised form at low pHs, PAA may associate with various non-ionic polymers (such as polyethylene oxide, poly-N-vinyl pyrrolidone, polyacrylamide, and some cellulose ethers) and form hydrogen-bonded interpolymer complexes In aqueous solutions PAA can also form polycomplexes with oppositely charged polymers (for example, chitosan), surfactants, and drug molecules (for example, streptomycin).
Labels
Community dentistry