Question

Dimethyl formamide (DMF) at boil is a solvent for

• A. Acrylic
• B. Nylon 6
• C. Nylon 66
• D. Wool

Hint:

DMF is widely used as a solvent for acrylic polymers due to its strong polarity and high boiling point.

Answer 1

The Correct Option is A

Step 1: Understanding DMF as a solvent.
Dimethyl formamide (DMF) is a strong polar aprotic solvent capable of dissolving certain synthetic polymers when heated to its boiling point.
Step 2: Behaviour of acrylic fibres.
Acrylic fibres, primarily composed of polyacrylonitrile, are soluble in DMF at elevated temperatures. Hence, DMF is commonly used as a solvent for acrylic polymers in fibre manufacturing and testing.
Step 3: Eliminating other options.
Nylon 6 and Nylon 66 are polyamides and are not dissolved by DMF under normal conditions. Wool is a natural protein fibre and is insoluble in DMF.
Step 4: Conclusion.
Therefore, DMF at boiling temperature acts as a solvent for acrylic fibres.

Answer 2

Dimethyl formamide (DMF) is a strong polar aprotic solvent, and whether it dissolves a given fibre at its boiling point depends on how well that solvent can break the fibre's intermolecular bonding. Checking each fibre type against this settles the answer.

1. Acrylic: Acrylic fibre is mainly polyacrylonitrile, held together largely by strong dipole-dipole interactions between nitrile groups rather than by hydrogen bonding; hot DMF's polarity is well matched to disrupting these nitrile-group interactions, which is why DMF at boil is the classic solvent used for acrylic in both manufacturing and lab testing.
2. Nylon 6: Nylon 6 is a polyamide held together by extensive hydrogen bonding between amide groups; DMF does not break this hydrogen-bonded network effectively, so nylon 6 is not dissolved by DMF under normal conditions.
3. Nylon 66: Nylon 66 shares the same hydrogen-bonded amide backbone as nylon 6, just with a different repeat unit, so it resists dissolution by DMF for the same reason.
4. Wool: Wool is a natural protein fibre with a complex, cross-linked structure, and this natural protein architecture is not broken down by DMF, so wool is insoluble in it.

Only acrylic's nitrile-based intermolecular bonding is the kind that hot DMF can effectively disrupt.

Therefore, the correct answer is Acrylic.