After surgical pleurodesis can a pneumothorax still happen?

Yes. Not all pleurodesis are the same. Depends on the agents used, the method of application, and the nature of your pathology, the success rate varies greatly.
Yes. As noted by drtsai, there are different techniques. On average, a vats pleuradesis that uses talc application has over 90-95% success rate in primary spontaneous pneumothorax. This means, there may be up to 10% of individuals, even after aggressive surgical and chemical pleuradesis, that have recurrence.