how to make a periodic boundary condition unitcell of PVDF

Hello,

I am begginer for material studio.
I'd like to make a polymer(pvdf), pleae help me
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this above figure is what I made in material studio.
but there is no periodic boundary condition.

Actually, I'd like to make PVDF unit cell like shown below which is consisting of one monomer.
please, let me know how to make this kind of periodic unit cell of polymer.

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