LONDON — Nicole Grobert is German, but she has spent almost all of her career in Britain, developing tiny nanomaterials and figuring out how to use them in everything from artificial bones to super-efficient batteries. Young scientists have an unusual degree of autonomy here, she has found, and European Union funds enabled her to build her own research group at the University of Oxford.

These days, though, Dr. Grobert says her future at Oxford looks cloudier than it used to. Since Britain voted to quit the union, she has been getting calls from universities on the Continent, and farther abroad, gauging her interest in a new job. For now, she is staying put, but if grants grow scarce or immigration rules create new hassles, she is ready to move.

“I came with a suitcase,” Dr. Grobert said. “I can grab that suitcase and go.”

For decades, the European Union has provided a collaborative, cross-border framework in which British universities have grown and thrived. European grants fund research like Dr. Grobert’s and nurture the international back-and-forth crucial to scholarly work in disciplines from archaeology to economics.

Free movement within the bloc has meant faculty from other European nations can live and work in Britain visa-free, and students from elsewhere in the union pay the same tuition as Britons.