Write the chemical equation for the termination step for radical polymerization of polyvinyl acetate by chain transfer

Research in the “unzipping” of poly(vinyl chloride) indicates that certain defects in the polymer contribute to the rate of unzipping. These defects are arrangements of atoms that are different from the arrangements in the repeating unit shown in the condensed formula. Researchers have found that defects involving allylic chlorides and tertiary chlorides, specifically, promote the reaction. Review the mechanism for the unzipping and explain this observation.

Styrene can autoinitiate free radical polymerization and form polystyrene in the absence of an initiator. At temperatures >100 °C, radicals form due to homolysis of the T bond in the vinyl group. In the study of this reaction, researchers have found 1,2-diphenylcyclobutane in samples of heated styrene. The following mechanism for the formation of 1,2-diphenylcyclobutane has been proposed: Step 1: Homolysis of the vinyl T bond in a styrene molecule Step 2: Homolysis of the vinyl T bond in a second styrene molecule Step 3: Tail-to-tail addition of the radicals from Steps 1 and 2 Step 4: Radical coupling of the diradical formed in Step 3 (a) Use curved arrow notation to show the steps in this mechanism. (b) Are the steps in this mechanism consistent with those for free radical polymerization? (c) Why is the use of an initiator such as benzoyl peroxide more efficient in the synthesis of polystyrene than autoinitiated polymerization?

In an end-group analysis of a polyester sample prepared from 4-hydroxybenzoic acid, the acid number was found to be 12.4 when it was titrated with standard potassium hydroxide, KOH. Determine the average degree of polymerization of this polyester sample. Given that the molecular weight of KOH= 56.1 g/mol and the molecular weight of the repeating unit of this polyester is 120 g/mol. Determine the osmotic pressure in milliliters of water at 25 °C for a 0.8 % (w/v) aqueous polymer sample solution at 5000 g/mol and 100,000 g/mol respectively. Ignore the nonideality of the solution. Comment on the effectivity. of this measurement technique. [Given that, gas constant, R = 8.3145 J mol¹¹ K-¹]