Polymerizable compound, polymerizable composition and liquid crystal display device

A polymerizable compound represented by formula (1):

• wherein, in formula (1),
• P1 and P2 are independently a polymerizable group;
• S1 and S2 are independently a single bond or alkylene having 1 to 10 carbons, in the alkylene, at least one of —CH2— may be replaced by —O—, —CO—, —COO— or —OCO—, at least one of —CH2—CH2— may be replaced by —CH═CH— or —C≡C—, and in the divalent groups, at least one of hydrogen may be replaced by halogen or alkyl having 1 to 3 carbons;
• R4 is hydrogen or —S1—P1, and R5 is hydrogen or —S2—P2;
• a1 and a2 are independently 0, 1, 2, 3 or 4;
• and
• a total of —S1—P1 and —S2—P2 is 2 to 8, and at least one of all of —S1—P1 and all of —S2—P2 is a monovalent group represented by formula (A):
• wherein, in formula (A), R1 and R2 are independently alkyl having 1 to 3 carbons, and R3 is hydrogen or methyl;
• and
• in formula (1),
• ring A1 and ring A2 are independently a divalent group derived from alicyclic hydrocarbon having 3 to 18 carbons, aromatic hydrocarbon having 6 to 18 carbons or heteroaromatic hydrocarbon having 3 to 18 carbons, in the divalent groups, at least one of hydrogen may be replaced by halogen, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 1 to 12 carbons or alkenyloxy having 1 to 12 carbons, and in the monovalent hydrocarbon groups, at least one of hydrogen may be replaced by halogen;
• Z1 is a single bond or alkylene having 1 to 10 carbons, in the alkylene, at least one of —CH2— may be replaced by —O—, —CO—, —COO— or —OCO—, at least one of —CH2—CH2— may be replaced by —CH═CH—, —C(CH3)═CH—, —CH═C(CH3)—, —C(CH3)═C(CH3)— or —CH≡CH—, and in the divalent groups, at least one of hydrogen may be replaced by halogen;
• and
• b1 is 0, 1, 2 or 3.