The EU tried this with Africa, doesn't work so great as long as there are countries which don't do it. That's one of the reasons China is successful in Africa, they don't care what the countries do as long as China gets what it wants.
If only there were a mulitlateral trade agreement that could unite all the western and Pacific nations in a Partnership against Chinese abuses.
The TPP actually had a rider on it preventing the deal from going through with countries that practice slavery. This effectively ruled out Malaysia.
In what is probably the lowest point in his career Obama objected and effectively said that slightly lower trade barriers mattered more than slavery.
How honorable! Try to force Chinese to bend their knees.