Chain End Modification of Poly isobutylene

The polymerizable function is incorporated by chemical modification of the a or co end group after isolation of the polymer. Although it is versatile since a wide variety of polymerizable groups can be incorporated, the method generally involves several steps. 

The synthesis of polyisobutylene methacrylate (MA-PIB) was first reported by Kennedy and Hiza [102]. The synthesis was accomplished by a multistep process. First IB was polymerized by the cumyl chloride/BCl3 initiating system. 

Macromonomers with two methacrylate functionalities (MA-PIB-MA) at both ends of the PIB chain have also been synthesized, by a procedure essentially identical to that reported above, but starting with a bifunctional initiator in the polymerization of IB [103]. Free radical copolymerization of the resulting MA-PIB-MA with 2-(dimethylamino)ethyl methacrylate resulted in amphiphilic networks, with a wide range of mechanical and swelling properties. 

The acrylate or methacrylate functional PIBs have also been used in UV-curable solventless coatings formulation in the presence of reactive diluents (multifunctional acrylate or methacrylate esters) and a UV-sensitizer [104]. The products were transparent, flexible films, with very little extractables, in which hard polyacrylate or polymethacrylate domains were dispersed in the soft PIB matrix. Tensile strength and ultimate elongation have also been obtained. 

In this process, epoxidation of the double bonds was followed by reduction to obtain the tert-alcohol which was esterified with methacryloyl chloride in the subsequent step. While epoxidation was found to be close to quantitative based on double bond content, reduction was incomplete and the residual epoxy functional PIB (24-47%) had to be separated by column chromatography before esterification. It should be noted that this macromonomer was a tert-ester which might be quite unstable in acidic conditions, and is also more hindered than the 

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