Preventing Escape
As others have mentioned, rendering him unconscious should do the trick. If you don't like that option, you could blindfold him, gag him, and chain him up, which should foil most escape attempts.
Imprisonment would certainly do the job. Flesh to Stone wouldn't inflict permanent harm on him and could also be used to hold him effectively indefinitely.
If you can find a way for the angel to treat him as a called creature, the advanced form of Magic Circle Against Alignment should hold him pretty securely. Unfortunately, the only spell I've found so far that allows you to call a creature against its will is Gate, so you might have to bend the rules slightly to make it work.
I agree that some kind of demiplane prison would work well, and they certainly exist in the Pathfinder universe - the church of Zon-Kuthon created several objects called midnight mirrors as prisons for their enemies. I doubt an angel would use an actual midnight mirror, but it's not hard to imagine that the armies of Heaven could construct a similar artifact that links to, say, a featureless white void rather than something based on the Plane of Shadow.
Making Escape Difficult
Bestow Curse wouldn't prevent him from escaping, but it would make escape substantially more difficult. If the angel is uncomfortable directly cursing someone, Mark of Justice would allow him to set a trigger condition like "if the target attempts to escape".