Am I sinful for agreeing to my friend, who is indebted to several usurious banks, buying a commodity for me with a credit card, which will not be repaid to the banks, knowing his intentions to escape from debts, and what should I do regarding this situation?

Usury is one of the gravest major sins. You erred by assisting your friend in it. You must repent sincerely and advise your friend to repent and return the rights to their rightful owners. If he does not respond, then do not associate with him, based on the Prophet's (peace be upon him) saying: "Do not associate except with a believer, and let no one eat your food except one who is pious."