Polymer - Implementing Model View Controller

I understand that some web applications can be written in pure Polymer as opposed to a framework such as Angular which has very obvious aspects for the MVC. In a nutshell, I'm confused about how a pure Polymer application can function as an MVC.

Naturally, Polymer consists of web components comprising the View layer, which follows the Composite pattern. How does it handle the model and controller aspects, assuming that Polymer can/does act as an MVC? Is external support needed for the Model aspect, with the "controllers" defined within each individual component to link to that model?

Thanks for any insights!