|“||I love you with all my heart. With every molecule, every atom. I love you on a sub-atomic level.||„|
|~ ~Brainard to Sara|
Professor Phillip Brainard is the main protagonist of Flubber.
He is a absentminded professor at a college and a small-time worker in his own basement, is trying to create a great invention. Unfortunately he always failed to invent something, but he is so obsessed about it that he even puts off his own wedding to his fiancée, Sara. One day, he finally invents something that works; this substance can cause even the heaviest things to bounce in the air, 'flying rubber', but Brainard called it "Flubber". However, he sees Sara going out with another professor from another college and several criminals trying to rob him. Brainard has to find out a way to defeat the criminals and to get back his fiancee. Hopefully, Flubber can help him.
Phillip Brainard is first seen waking up and going to work at Medfield College as he develops a new energy source in order to raise enough money to save the college from being closed. He gets distracted from his research by his love interest and fiancee, Sara Jean Reynolds, due to the fact that he has missed the last two weddings. On the day of the third wedding, Phillip gets approached by his former partner, Wilson Croft, who has profited from the ideas and threatens to steal Sara from Phillip and make her his wife. Phillip skips the third wedding and does his latest experiment along with his hovering mechanical partner, Weebo, as he discovers a green goo-like thing, but it escapes, causing havoc, but Phillip eventually catches it and decides to call it Flubber.
The next day, Phillip realizes that he has missed the third wedding and Sara becomes really upset at him and also tells him that their relationship is over after Phillip fails to explain what happened. That night, Phillip begins more tests with the Flubber experiment, as Chester Hoenicker's henchmen try to steal Flubber, but are knocked out by the golf ball and the bowling ball coated in Flubber gel and are bounced by the Flubber liquid. Phillip then tests his vintage Ford Thunderbird convertible with the Flubber plutonium in the engine, allowing it to fly. While testing his car with Flubber, he discovers that Wilson is beginning a relationship with Sara. After testing Flubber on one of the basketball players, Weebo goes to Sara's house and shows Sara the footage about Phillip.
Sara reconciles with Phillip and Phillip demonstrates Flubber to Sara in order to raise enough money to save the college. Phillip and Sara discover that Weebo has been destroyed by one of Hoenicker's goons and Flubber is kidnapped. Phillip and Sara had to get revenge on Hoenicker as they try to rescue Flubber when they realize that Wilson is allied with the millionaire. Phillip and Sara had to fight Hoenicker, Wilson and his goons and they are able to defeat them by using the Flubber liquid on the bottom of their shoes and get Flubber as they raise enough money to save the college. Phillip and Sara are now married and Flubber becomes their son and the daughter of Weebo and her replacement, Weebette becomes their daughter as the family go to Hawaii in Phillip's car at the end of the film.
- Christopher Lloyd, Jeff Goldblum, John Lithgow, Tim Allen and Patrick Stewart were all considered for the role of Phillip Brainard before Robin Williams was cast.