I've always taken the view that 'bosses' don't actually need to know what I'm up to and generally might want to trust me. Thus, I don't ask to take time to research but just do it - as long as the rest of my work is done it doesn't matter. Maybe others have more pressure or I am just able to get things done quickly but I can almost always find an hour or two a day to follow interesting lines of development. I guess it doesn't hurt that mostly such work will get fed back in fairly quickly.