content_image/907184.jpg content_image/907186.jpg content_image/907187.jpg
<img src='content_image/907184.jpg'>

[0084] Examples of the monomer from which the recur- ring units (a2) are derived are shown below, but not limited thereto. RA and R$^{12 }$are as defined above. 

<img src='content_image/907186.jpg'>

<img src='content_image/907187.jpg'>

