Animated Solution for Chemistry - Polymers: The polymer containing strong intermolecular forces e.g., hydrogen bonding, is

Understanding Intermolecular Forces in Polymers

When we look at everyday materials—from the stretchy rubber in our tires to the tough nylon ropes used in rock climbing—we are actually witnessing the macroscopic effects of microscopic forces. Polymers are giant molecules, but their physical properties are largely dictated by how these giant chains interact with one another. These interactions are governed by intermolecular forces.

In this problem, we are on a hunt for a specific, highly potent type of intermolecular force: Hydrogen Bonding.

Before we analyze the suspects, let's establish the ground rules. What exactly is required for a hydrogen bond to form?

Hydrogen bonding is a special, unusually strong type of dipole-dipole interaction. It occurs when a hydrogen atom is covalently bonded to a highly electronegative atom—specifically Fluorine ($F$), Oxygen ($O$), or Nitrogen ($N$). Because these atoms are so greedy for electrons, they pull the electron cloud away from the hydrogen, leaving it with a strong partial positive charge. This "exposed" proton can then strongly attract lone pairs of electrons from electronegative atoms on neighboring molecules.

Let's put our options through the hydrogen-bond test:

1. Teflon: The chemical formula for Teflon is $(-{\text{CF}}_2-{\text{CF}}_2-{)}_n$. While it contains highly electronegative fluorine atoms, there are absolutely no hydrogen atoms present in the structure. Without hydrogen, there can be no hydrogen bonding. Teflon chains slide past each other easily, which is why it's used as a non-stick coating!

2. Polystyrene: This is a hydrocarbon polymer containing a long carbon backbone with bulky benzene rings attached. It contains only carbon and hydrogen. Since carbon is not highly electronegative, the $C-H$ bonds are relatively non-polar. The only forces holding polystyrene chains together are weak van der Waals dispersion forces.

3. Natural Rubber: Chemically known as polyisoprene, this is also a pure hydrocarbon. Similar to polystyrene, it lacks the highly electronegative atoms required for hydrogen bonding. The weak intermolecular forces allow the chains to uncoil and stretch, giving rubber its characteristic elasticity.

Nylon 6,6

Now we arrive at Nylon 6,6. Nylon belongs to a family of polymers known as polyamides. As the name suggests, the polymer backbone is held together by amide linkages.

The structure of an amide linkage is $-\text{C}(=\text{O})-\text{NH}-$.

Look closely at this functional group. It contains a carbonyl oxygen ($C=O$), which has lone pairs of electrons and a partial negative charge. Right next to it is an amine group ($N-H$), where the hydrogen is attached to a highly electronegative nitrogen atom, giving it a strong partial positive charge.

When two Nylon chains align next to each other, the partially positive hydrogen of one chain forms a strong electrostatic attraction with the partially negative oxygen of the adjacent chain. This creates a dense, highly organized network of hydrogen bonds across the polymer chains.

Because of these strong intermolecular forces, the chains are packed tightly together in a crystalline lattice. This is exactly why Nylon is classified as a fibre—it possesses high tensile strength, high melting point, and resistance to stretching, making it perfect for ropes, fabrics, and parachutes.

Therefore, Nylon 6,6 is the undisputed winner of our hydrogen bonding contest!