soak them in lukewarm water for half an hour.

I had all this in my art file but I cant site the source

Cleaning and care are sooo important. Fine brushes will last a very long time if used and cared for properly. If you always seem to destroy brushes find out why. Otherwise,a different style or better grade of brush would be a waste of money.
The most common problems is accumulated paint in the "heel" of the brush, where the fiber meets the ferrule. To prevent this, do not immerse the brush in paint up to the ferrule, and always load and use the brush in the natural direction of the hair. Even wet paint is hard to completely remove from the heel area and if it dries, even more difficult. The paint residue causes a hard lump of glued-together hair. The brush loses its resiliency and new paint will not flow evenly. All excess paint should be removed with a rag or paper toweling to get out as much paint as possible before putting the brush in solvent. Then, use the appropriate cleaner or solvent for the medium. Dont leave a brush soaking in liquid, especially resting on its head. While you may intend to get right back to painting, things may prevent it and two days later the brush is in an entirely different shape, and ruined. Brushes must be cleaned thoroughly after each session. They should be either laid flat or suspended with the head down to dry so that all excess fluid drains away from the ferrule. After they are completely dried, they can be stored upright, on their ends, or put away in a brush carrier.

BUT... then comes the odd ball who says things about acrylic brushes like the following

Tip droop: When the smaller acrylic brushes eventually end-up with the tip of the brush bent at 90 degree angle, giving a hooked effect, just learn to use the extra advantage the odd shape gives you. You can see exactly where the tip is lined up and draw it to you and you can drag it sidewards to creat broader lines than the brush normally would give.

Wild hairs: unlike natural hair brushes, acrylic brushes will often get split-ends and small fibers down the shaft beginning to stick-out at odd angles. Just use a small, portable nail clipper to tease the wild hair out of the brush and snip it off - which is actually easier to do while the brush is full of paint as the offending fiber will be much more noticable than when the brush is clean.

Dried paint: The base of a brush or ferrel will often times become clogged with dried paint, making the brush splay apart in odd ways or fail to keep a point. Or you will have dry-brushed too long without cleaning the brush and paint will have dried completly, marring the bristles. I keep a sealed tall bottle on my painting table filled with ordinary rubbing alchohol, which is the soverign remedy for acrylic paint of all sorts. Merely insert your brushes in the alchohol bath for a while with the capped jar laying on its side. When you swirl them about and you will see small clouds of dissolving paint come drifting-out. Do this until the paintbrush is clean - you will find it will extend the useful life of your brushes by restoring their flexiablity and shape. It may cause the paint to peel off of the handle but it can save a favorite brush from the trash can.

A trip to the alchohol bath is also a useful way of stripping paint off a figure that you are not happy with and wish to try again!