Obamacare part-timism: A myth debunked.:

My strong suspicion is that if the ACA has an impact on the labor force (which it probably will) it will be through a different mechanism. Right now “in order to qualify for health benefits” is a very good reason to work full-time, even if you’d rather have more free time and less money at your current wage level. The Affordable Care Act will make this benefit qualification rationale less compelling,

The changes to part time employment in the past few years has almost nothing to do with Obamacare and everything to do with improved scheduling and time management systems in retail, hospitality and fast food sectors.