Question

Poly (vinyl alcohol), a hydrophilic polymer used in aqueous adhesives, is made by polymerizing vinyl acetate and then hydrolyzing the ester linkages.

(a) Give the structures of poly (vinyl acetate) and poly (vinyl alcohol).

(b) Vinyl acetate is an ester. Is poly (vinyl acetate) therefore a polyester? Explain.

(c) We have seen that basic hydrolysis destroys the Dacron polymer. Poly (vinyl acetate) is converted to poly (vinyl alcohol) by a basic hydrolysis of the ester groups. Why doesn’t the hydrolysis destroy the poly (vinyl alcohol) polymer?

(d) Why is poly (vinyl alcohol) made by this circuitous route? Why not just polymerize vinyl alcohol?

Short answer

(b)Poly (vinyl acetate) is not a polyester since ester functional group is not involved in bond formation.

(c)Hydrolysis of poly (vinyl acetate) to poly (vinyl alcohol) does not destroy the poly (vinyl alcohol) polymer because the ester group is out of the main chain.

(d) Vinyl alcohol is in equilibrium with its aldehyde form.

Step-by-step solution

Ester

The functional group in which carbon atom is bound to three other atoms namely, a single bond to a carbon atom, a double bond to an oxygen atom, and also a single bond to an oxygen atom. The singly bound oxygen atom is bound to another carbon

atom. This type of functional group is known as an ester. In lactone, ester functional group becomes a part of the ring structure with carbon atoms.

Explanation

(b) Poly (vinyl acetate) is not a polyester since ester functional group is not involved in bond formation.

(c) Hydrolysis of poly (vinyl acetate) to poly (vinyl alcohol) does not destroy the poly (vinyl alcohol) polymer because the ester group is out of the main chain.

(d) Because vinyl alcohol is in equilibrium with its aldehyde form.