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The wool absorbed the dye the strongest followed by the silk. Cotton and nylon absorbed the dye
slightly giving a yellow color. Polyester did not absorb the dye well at all.
Because of wools structure, which contains amine and ketone groups, it is very polar. It is also an amino
acid chain (poly peptide). The polarity of the wool enables the methyl red (which is also very polar
because of 1 carboxylic acid group, tertiary nitrogen, and a double bond nitrogen bridge that connects
the two aromatic rings of the methyl red molecule) to bond with the wool very well. The biggest factor
in which the dye bonds to the wool is that hydrogen bonds can form between the OH on the dye and
the Nitrogens and Oxygens within the amino acid structure.
Silk absorbed very well also. This is because the nitrogens and carbonyls within the polypeptides in the
amino acid sequence of the silk fabric. This allows for the Hydrogen bonding between the OH of the dye
and the carbonyl and Nitrogens within the polypeptide chain. Also, the polarity of these polar amino
acids allow for better dying of the silk fabric.
Nylon and cotton were not dyed as easily because not as much hydrogen bonding could occur. Many
hydroxyl groups are present on cotton. These are the only functional groups on cotton that can
hydrogen bond with the dye. Other than the hydroxyl groups that are present on the cellulose that
makes up cotton’s fibers, no other hydrogen bonding can occur on the glucose monomers of cotton. The
reason why it is able to be dyed to at least make a yellow color is because of the vast amount of
hydroxyl groups present on cellulose. Nylon is a polyamide. It contains amide groups which make it
slightly polar but not polar enough to absorb the dye as well as wool. Also, it doesn’t have many
functional groups that can hydrogen bond with the dye. The only part of the polymer that can form a
hydrogen bond with the dye is the nitrogen adjacent to the carbonyl. This means that the dye won’t
stick very well to the fabric and will fade and won’t dye the fabric as well as it should.
Polyester did not dye well at all. It kept almost the same color. This is due to its slightly polar nature and
containing so few functional groups in which the dye can hydrogen bond to. Therefore, the fabric will
not be dyed very well.
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The wool absorbed the dye the strongest followed by the silk.docx
Displaying The wool absorbed the dye the strongest followed by the silk.docx.
