No, has nothing to do with the sperm, has to do with chemical reactions in the body when a body is being harmed.
This is the exact sort of ignorance that Akin was preaching. There’s no magic “chemical reaction”, if a woman is ovulating and she gets raped, if the rapist ejaculates inside her and the sperm reaches the egg, boom, you have pregnancy just as you would at any other time.
Nothing ultra-mysterious or complicated about it.