Question

What is polystyrene? The following processes result in a stronger polystyrene polymer. Explain why in each case. a. addition of catalyst to form syndiotactic polystyrene b. addition of 1,3 -butadiene and sulfur c. producing long chains of polystyrene d. addition of a catalyst to make linear polystyrene

Short answer

Polystyrene is a versatile synthetic polymer derived from the monomer styrene. The strength of polystyrene can be enhanced in a few ways: a) Forming syndiotactic polystyrene with a catalyst creates a more crystalline structure, increasing molecular packing and intermolecular forces; b) Adding 1,3-butadiene and sulfur results in vulcanized, high-impact polystyrene due to cross-linking of polymer chains; c) Producing longer chains increases surface area for entanglement and intermolecular forces, improving physical properties; d) Catalyst-induced linear polystyrene formation minimizes branch disruption and increases crystallinity for greater mechanical strength.

Step-by-step solution

Polystyrene Basics

Polystyrene is a synthetic polymer derived from the monomer styrene. It is a versatile plastic used in various applications due to its properties such as transparency, rigidity, and low cost. The properties of polystyrene can be altered with the addition of specific catalysts or other additives, so let's look at each specific case to understand its effects on strength.

a. Syndiotactic Polystyrene Formation

The addition of a catalyst to form syndiotactic polystyrene alters the arrangement of the phenyl groups on the polymer chain. In a syndiotactic configuration, these groups are regularly alternating in position on both sides of the chain. This results in a more ordered, crystalline structure compared to the amorphous nature of conventional polystyrene. The increased regularity in structure allows for tighter molecular packing and stronger intermolecular forces, ultimately leading to a stronger polymer.

b. Addition of 1,3-Butadiene and Sulfur

Adding 1,3-butadiene and sulfur to polystyrene results in a process called vulcanization. Vulcanized polystyrene, also known as high-impact polystyrene (HIPS), has rubber-like properties due to the cross-linking of polymer chains created by these additives. This cross-linking increases the strength of the material by restricting the movement of individual chains and creating a more interconnected network.

c. Producing Long Chains of Polystyrene

Longer chains of polystyrene result in an increase in molecular weight, which usually leads to improved physical properties like tensile strength, elongation at break, and impact resistance. When polystyrene chains are longer, there is a greater surface area for entanglement and intermolecular forces such as van der Waals interactions. These factors contribute to the overall strength of the material.

d. Linear Polystyrene Formation

Adding a catalyst to form linear polystyrene encourages the formation of an unbranched polymer structure. With fewer branches in the polymer chain, there is less opportunity for disruption to the crystallinity of the material. A more highly crystalline structure results in closer molecular packing, which in turn leads to stronger intermolecular forces and increased mechanical strength.