Pure mentions in podcasts have actually been shown to be not the best way to get your listeners to interact with a sponsor. While sponsors often require them, to assure they are getting their fair share of airtime, it is often better to put more of a personal twist on them. Why you use them, small audio bits about ways to maximize their products effectiveness, etc. Also, when you mention them is just as important. Most listeners tend to tune out at the beginning and end of shows, because this is when most people plug sponsors. That is why sponsored segments, in conversation mentions, and such work much better.
Landing a sponsor is a great feeling, but you need to educate yourself on how to present them effectively, or you will soon be following that up with the worst feeling: Losing one.