Polythiophene, water-soluble electrically conductive polymer using it, and method for producing it

A polythiophene comprising at least one type of structural units selected from the group consisting of structural units represented by the following formula (3), structural units represented by the following formula (4), structural units represented by the following formula (5) and structural units represented by the following formula (6):

• wherein Ar is a C6-20 arylene group which may have a substituent, X is a C1-6 alkylene group which may have a substituent, M is a hydrogen atom, an alkali metal selected from the group consisting of Li, Na and K, NH(R1)3 or HNC5H5, R1 is each independently a hydrogen atom or a C1-6 alkyl group which may have a substituent, n is an integer of from 0 to 6, m in an integer of 0 or 1, and l is an integer of from 1 to 4;
• wherein Ar, X, n, m and l are as defined in the above formula (3);
• wherein R is a C1-6 linear or branched alkyl group, or a fluorine atom, M is a hydrogen atom, an alkali metal selected from the group consisting of Li, Na and K, NH(R1)3 or HNC5H5, and R1 is each independently a hydrogen atom, or a C1-6 alkyl group which may have a substituent;
• and
• wherein R is as defined in the above formula (5).