Fluoropolymer production method and fluoropolymer

A fluoropolymer comprising:

• a segment A consisting of a monomer unit of tetrafluoroethylene;
• and
• a segment B containing at least one of a monomer unit derived from a monomer represented by the formula (1) or a monomer unit derived from a monomer represented by the formula (2),
• the formula (1):
• CF2═CR1R2
• wherein R1 is H;
• R2 is —Cl, —Ra, —COORb, —OCORc, —CONRd2, —CN, —CORe, or —Rfa;
• Ra, Rb, Rc, Rd, and Re are the same as or different from each other and are each H or a substituent;
• Rfa is the same as or different from each other and is an optionally substituted fluorine-containing alkyl group, an optionally substituted fluorine-containing vinyl group, or an optionally substituted fluorine-containing alkoxy group, each group optionally containing an oxygen atom between carbon atoms;
• and R1 and R2 optionally bind to each other to form a ring,
• the formula (2):
• CH2=CR3R4
• wherein R3 is Rg, CF3, or F;
• R4 is —Cl, —Rh, —COORi, —OCORj, —CONRk2, —CN, —CORm, or Rfc;
• Rg and Rh are the same as or different from each other and are each H, an optionally substituted hydrocarbon group, or an optionally substituted heterocyclic group;
• Ri, Rj, Rk, and Rm are the same as or different from each other and are each H or a substituent;
• Rfc is the same as or different from each other and is an optionally substituted fluorine-containing alkyl group, an optionally substituted fluorine-containing vinyl group, or an optionally substituted fluorine-containing alkoxy group, each group optionally containing an oxygen atom between carbon atoms;
• and R3 and R4 optionally bind to each other to form a ring,
• wherein when the segment B contains a monomer unit of vinylidene fluoride (VDF), the segment B consists of the monomer unit of vinylidene fluoride (VDF).