
revaar |

Normally, you cannot grapple with a Whip, as grapple is a non weapon based maneuver. However, there is a feat which allows you to do so, Greater Whip Mastery. According to the feat, the wielder does not gain the grappled condition, but you'd need to keep a hand on it.

Gwen Smith |

Just FYI: Weapons with the "grapple" quality don't actually let you perform a grapple maneuver with the weapon (like a trip or disarm weapon does). The grapple weapon quality means that if you score a critical hit with the weapon you get a free grapple attempt with no AoO.
Now, your GM might let you use a "grapple" weapon to do a normal grapple combat maneuver (I would), but that's up to your GM.