Thermoassociative additive compositions, the association of which is controlled, and lubricating compositions containing same

A composition resulting from the mixing of at least

• one polydiol random copolymer A1,
• one compound A2 comprising at least two boronic ester functions,
• one exogenous compound A5 chosen from those corresponding to formula (XI):
• in which:
• Q represents a group chosen from a hydrocarbon-based group comprising from 1 to 30 carbon atoms, optionally substituted with one or more groups chosen from:
• a hydroxyl, a group —OJ or —C(O)—O-J with J being a hydrocarbon-based group comprising from 1 to 24 carbon atoms,
• G4 and G5, which may be identical or different, represent groups chosen from a hydrogen atom, a C1-C24 alkyl, a hydroxyl and a group —OJ or —C(O)—O-J with J being a C1-C24 alkyl,
• g represents 0 or 1,
• wherein the molar percentage of exogenous compound A5 relative to the diol functions of the random copolymer A1 ranges from 1% to 150% and the mass ratio between copolymer A1 and compound A2 (ratio A1/A2) ranges from 0.05 to 20,
• wherein the random copolymer A1 results from the copolymerization:
• of at least one first monomer M1 of general formula (I):
• in which:
• R1 is chosen from the group formed by —H, —CH3 and —CH2—CH3;
• x is an integer ranging from 1 to 18;
• y is an integer equal to 0 or 1;
• X1 and X2, which may be identical or different, are chosen from the group formed by hydrogen, tetrahydropyranyl, methyloxymethyl, tert-butyl, benzyl, trimethylsilyl and t-butyldimethylsilyl;
• or
• X1 and X2 form, with the oxygen atoms, a bridge having the following formula
• in which:
• the asterisks (*) symbolize the bonds to oxygen atoms,
• R′2 and R″2, which may be identical or different, are chosen from the group formed by hydrogen and a C1-C11 alkyl;
• or
• X1 and X2 form, with the oxygen atoms, a boronic ester having the following formula:
• in which:
• the asterisks (*) symbolize the bonds to oxygen atoms,
• R′″2 is chosen from the group formed by a C6-C30 aryl, a C7-C30 aralkyl and a C2-C30 alkyl;
• with at least one second monomer M2 of general formula (II):
• in which:
• R2 is chosen from the group formed by —H, —CH3 and —CH2—CH3,
• R3 is chosen from the group formed by a C6-C18 aryl, a C6-C18 aryl with a group R′3, —C(O)—O—R′3, —O—R′3, —S—R′3 and —C(O)—N(H)—R′3 with R′3 being a C1-C30 alkyl group.