content_image/894909.jpg content_image/894910.jpg content_image/894913.jpg content_image/894914.jpg
<img src='content_image/894909.jpg'>

Examples of the recurring unit having formula (D-2) are 15 shown below, but not limited thereto. Herein RA is as defined above. 

<img src='content_image/894910.jpg'>

Examples of the recurring unit having formula (D-3) are shown below, but not limited thereto. Herein RA is as defined above. 

<img src='content_image/894913.jpg'>

<img src='content_image/894914.jpg'>

