Lab 2 PS-PMMA - CHEM 5384 Polymer Characterization II Lab 2...

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CHEM 5384 Polymer Characterization II Lab 2: ATRP copolymerization of styrene and methyl methacrylate (MMA) Mengfang Li 02/05/2012 Introduction: In this experiment we were introduced the method to control a radical process to prepare well- defined copolymer of styrene and methyl methacrylate. Atom transfer radical polymerization (ATRP) using copper complex was developed to eliminate the classical mode of terminations. In this method, almost all polymer chains start growing at same time. The polymerization rate is controlled by exchange of halogen atom between a metal catalyst and propagating radical [1,2] . This, combined with fast initiation from a small organic halide, R–X, with a sufficiently reactive C–X bond, leads to a polymer sample of fairly uniform molecular weight chains, which retain the halogen end group, X.As a result, the similar reactivity of radical chain ends almost regardless of the monomer structure increases the possible combinations of statistical
copolymers that are accessible to radical polymerization [3] . Figure 1. Mechanism of atom transfer radical polymerization (ATRP) [1] In the previous lab described in last report, poly(styrene) (PS, Tg = 100 °C) was prepared from a monofunctional initiator and the kinetics of the homopolymerization by ATRP were measured. This monofunctional PS-Br macroinitiator was then chain-extended with poly(methyl methacrylate) (PMMA, Tg = 95 °C). Molecular weights were measured by gel permeation chromatography (GPC), and composition of the copolymers was determined using 1H NMR (300 MHz).

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