Yes, an opportunity attack is triggered.
Although the blink spell does not explicitly use the word teleport, I believe that teleportation is essentially what it does.
Regarding teleportation the rules for how it works with opportunity attacks without polearm master are as follows:
You also don’t provoke an opportunity attack when you teleport or when someone or something moves you without using your movement, action, or reaction. (PHB p.195) (emphasis added).
So in normal circumstances it would be impossible to for a teleport to trigger an opportunity attack. However the pole arm master feat states:
While wielding a glaive, halberd, pike, or quarterstaff, other creatures provoke an opportunity attack from you when they enter your reach. (emphasis added).
Since teleporting into someones reach involves entering their reach we can assume that the perquisites for an opportunity attack via the pole arm master feat are met.
This interpretation of the rules relies on the belief that specific beats general and that the rules for a feat are more specific than the general rules regarding teleportation/opportunity attacks.