Question

Describe the effects on the skeletal structure of the polymer produced if some ethylene glycol dimethacrylate were included in a polymerization of methyl methacrylate (see entry (5) of table 1.1).

Options:
a) Increased flexibility
b) Increased brittleness
c) No change in structure
d) Enhanced elasticity

Answer 1

Including ethylene glycol dimethacrylate in the polymerization of methyl methacrylate would lead to cross-linking in the polymer structure, thus enhancing the mechanical strength and rigidity, creating a thermoset polymer with greater structural integrity.

Step-by-step explanation:

When ethylene glycol dimethacrylate is included in the polymerization of methyl methacrylate, it acts as a cross-linking agent. This cross-linking will cause the chains of the polymer to bind together at various points, creating a three-dimensional network. The presence of these cross-links enhances the mechanical strength and rigidity of the resulting polymer. Hence, it would not increase flexibility or brittleness, nor would it make the polymer unchanged or more elastic. Cross-linked polymers are generally stronger and more resistant to deformation than those without cross-links. Therefore, the effect on the skeletal structure of the polymer would be to create a stiff, strong matrix, leading to an enhanced structural integrity.

This introduction of cross-links effectively creates a thermoset polymer, whereas polymers without cross-linking, like regular poly(methyl methacrylate), are thermoplastics. Thermosets do not melt but can degrade when exposed to high temperatures, while thermoplastics can be remelted and reshaped. Including ethylene glycol dimethacrylate in the polymerization process will thus convert the polymer from a thermoplastic to a thermoset, enhancing its strength but reducing its ability to be remolded upon reheating.