Broil pork chops before roasting?
There's really no such thing as 'sealing in juices' when it comes to meat. Skin-on chicken breast stays relatively moist because of the fat in the skin; because the skin is on top, it pretty much self-bastes. Broiling just crisps the skin afterwards and will do nothing moisture-wise.

With pork chops, however, the fat is around the side and so will drip off during roasting, and broiling beforehand will just dry out the surface of the meat. I'd suggest rolling the fat in some salt, then placing the chops fat side down on a warm pan for a few minutes. This will render out the fat. You can then drizzle this on to the pork to help keep it moist and impart extra flavor.