Conventional Free Radical Polymerization ofN‐VinylPyrrolidone Homopolymers

Abstract

This chapter focuses on the synthesis of polyvinyl pyrrolidone (PVP) in a variety of forms, and describes methodologies to produce soluble, branched, and crosslinked versions. It explains critical factors involved in the conventional free‐radical polymerization processes employing thermal initiators to manufacture PVP. PVP is soluble in water and polar solvents, insoluble in esters, ethers, and hydrocarbons. There are generally two types of free‐radical initiator used commercially. These are peroxide‐based, or azo‐based. Molecular weight control over the polyvinyl pyrrolidone polymer is affected by both the initiator concentration as well as the monomer concentration. The use of a water soluble azo‐initiator in the polymerization of N‐vinyl pyrrolidone was performed using Vazo‐50 initiator. Azo‐mediated N‐vinyl pyrrolidone homopolymerization in water can be initiated by sparingly soluble to freely‐soluble azo‐initiators. A number of different approaches to reduce residual monomer levels have been applied in the production of free‐radical polymers.