Polystyrene results when styrene monomers interconnect. In the polymerization, the carbon-carbon pi bond (in the vinyl group) is broken and a new carbon-carbon single (sigma) bond is formed, attaching another styrene monomer to the chain. The newly formed sigma bond is much stronger than the pi bond that was broken, thus it is very difficult to depolymerize polystyrene. About a few thousand monomers typically comprise a chain of polystyrene, giving a molecular weight of 100,000–400,000.
A 3-D model would show that each of the chiral backbone carbons lies at the center of a tetrahedron, with its 4 bonds pointing toward the vertices. Consider that the -C-C- bonds are rotated so that the backbone chain lies entirely in the plane of the diagram. From this flat schematic, it is not evident which of the phenyl (benzene) groups are angled outward from the plane of the diagram, and which ones are inward. The isomer where all of the phenyl groups are on the same side is called isotactic polystyrene, which is not produced commercially.
Polystyrene results when styrene monomers interconnect. In the polymerization, the carbon-carbon pi bond (in the vinyl group) is broken and a new carbon-carbon single (sigma) bond is formed, attaching another styrene monomer to the chain. The newly formed sigma bond is much stronger than the pi bond that was broken, thus it is very difficult to depolymerize polystyrene. About a few thousand monomers typically comprise a chain of polystyrene, giving a molecular weight of 100,000–400,000.A 3-D model would show that each of the chiral backbone carbons lies at the center of a tetrahedron, with its 4 bonds pointing toward the vertices. Consider that the -C-C- bonds are rotated so that the backbone chain lies entirely in the plane of the diagram. From this flat schematic, it is not evident which of the phenyl (benzene) groups are angled outward from the plane of the diagram, and which ones are inward. The isomer where all of the phenyl groups are on the same side is called isotactic polystyrene, which is not produced commercially.
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