you cannot avoid chemicals, you drink dihydrogen monoxide.
I had X-tenso a couple of times and if correctly applied it got rid of my frizz for a year. Current hairdresser uses Wellastrate, done twice now (a year apart) and it is BRILLIANT, also lasts a year. I've gone from frizzy mop to swishy vague waves - I like it straight which takes five mins with the straighteners. Wash every 3-4 days now, blow drying does make it dry straighter. I can use a comb and it is so much more comfortable too.
you'll need the intense version if you have frizzy hair. But you can't have that if you have coloured hair, that needs the mild one. This might also leave you with the curls, ask.
added bonus is that it turns grey streaks into blonde ones (I have brown hair). Takes years off me too.
one hairdresser cocked it up and it fell out after 3 months. Correct sequence is wash, apply straightener (that takes a while), sit v. still and leave for appropriate time, rinse, blow dry, straighten, apply neutraliser, wash, condition, blow dry, straighten. Five hours, £140. Then don't wash, tie back, tuck behind ears or get wet for as long as possible to let it really set in - five days.
yes, does smell - needs an open window in the salon.