Composition of additives resulting from mixing at least: - a polydiol random copolymer A1, - a random copolymer A2 comprising at least two boronic ester functions and able to associate with said polydiol random copolymer A1 by at least one transesterification reaction, - an exogenous compound A4 selected from the 1,2-diols and the 1,3-diols, wherein the weight ratio of the polydiol random copolymer A1 to the random copolymer A2 (A1/A2 ratio) ranges from 0.005 to 200, the molar percentage of exogenous compound A4 relative to the boronic ester functions of the random copolymer A2 ranges from 0.025 to 5000%, the random copolymer A1 results from the copolymerization: ▪ of at least one first monomer M1 of general formula: in which: - R 1 is selected from the group formed by -H, -CH 3, and -CH 2 -CH 3; - x is an integer ranging from 1 to 18; preferably from 2 to 18; - y is an integer equal to 0 or 1; - X 1 and X 2, identical or different, are selected from the group formed by hydrogen, tetrahydropyranyl, methyloxymethyl, tert-butyl, benzyl, trimethylsilyl and t-butyl dimethylsilyl; or - X 1 and X 2 form, with the oxygen atoms, a bridge of the following formula in which: - the stars (*) represent the bonds to the oxygen atoms, - R' 2 and R" 2, identical or different, are selected from the group formed by hydrogen and a C 1 -C 11 alkyl, preferably methyl; or - X 1 and X 2 form, with the oxygen atoms, a boronic ester of the following formula: in which: - the stars (*) represent the bonds to the oxygen atoms, - R'" 2 is selected from the group formed by a C 6 -C 18 aryl, a C 7 -C 18 aralkyl and C 2 -C 18 alkyl, preferably a C 6 -C 18 aryl; ▪ with at least one second monomer M2 of general formula: in which: - R 2 is selected from the group formed by -H, -CH 3 and -CH 2 -CH 3, - R 3 is selected from the group formed by a C 6 -C 18 aryl, a C 6 -C 18 aryl substituted with an R' 3 group, -C -O-R' 3; -O-R' 3, -S-R' 3 and -C -N -R' 3 with R' 3 a C 1 -C 30 alkyl group, the molar percentage of monomer M1 of formula in the random copolymer A1 ranging from 1 to 30%, and the molar percentage of monomer comprising boronic ester functions in random copolymer A2 ranging from 0.25 to 20%. - a polydiol random copolymer A1, - a random copolymer A2 comprising at least two boronic ester functions and able to associate with said polydiol random copolymer A1 by at least one transesterification reaction, - an exogenous compound A4 selected from the 1,2-diols and the 1,3-diols, ▪ of at least one first monomer M1 of general formula: in which: - R 1 is selected from the group formed by -H, -CH 3, and -CH 2 -CH 3; - x is an integer ranging from 1 to 18; preferably from 2 to 18; - y is an integer equal to 0 or 1; - X 1 and X 2, identical or different, are selected from the group formed by hydrogen, tetrahydropyranyl, methyloxymethyl, tert-butyl, benzyl, trimethylsilyl and t-butyl dimethylsilyl; or - X 1 and X 2 form, with the oxygen atoms, a bridge of the following formula in which: - the stars (*) represent the bonds to the oxygen atoms, - R' 2 and R" 2, identical or different, are selected from the group formed by hydrogen and a C 1 -C 11 alkyl, preferably methyl; or - X 1 and X 2 form, with the oxygen atoms, a boronic ester of the following formula: in which: - the stars (*) represent the bonds to the oxygen atoms, - R'" 2 is selected from the group formed by a C 6 -C 18 aryl, a C 7 -C 18 aralkyl and C 2 -C 18 alkyl, preferably a C 6 -C 18 aryl; - R 1 is selected from the group formed by -H, -CH 3, and -CH 2 -CH 3; - x is an integer ranging from 1 to 18; preferably from 2 to 18; - y is an integer equal to 0 or 1; - X 1 and X 2, identical or different, are selected from the group formed by hydrogen, tetrahydropyranyl, methyloxymethyl, tert-butyl, benzyl, trimethylsilyl and t-butyl dimethylsilyl; or - X 1 and X 2 form, with the oxygen atoms, a bridge of the following formula in which: - the stars (*) represent the bonds to the oxygen atoms, - R' 2 and R" 2, identical or different, are selected from the group formed by hydrogen and a C 1 -C 11 alkyl, preferably methyl; or - the stars (*) represent the bonds to the oxygen atoms, - R' 2 and R" 2, identical or different, are selected from the group formed by hydrogen and a C 1 -C 11 alkyl, preferably methyl; or - X 1 and X 2 form, with the oxygen atoms, a boronic ester of the following formula: in which: - the stars (*) represent the bonds to the oxygen atoms, - R'" 2 is selected from the group formed by a C 6 -C 18 aryl, a C 7 -C 18 aralkyl and C 2 -C 18 alkyl, preferably a C 6 -C 18 aryl; - the stars (*) represent the bonds to the oxygen atoms, - R'" 2 is selected from the group formed by a C 6 -C 18 aryl, a C 7 -C 18 aralkyl and C 2 -C 18 alkyl, preferably a C 6 -C 18 aryl; ▪ with at least one second monomer M2 of general formula: in which: - R 2 is selected from the group formed by -H, -CH 3 and -CH 2 -CH 3, - R 3 is selected from the group formed by a C 6 -C 18 aryl, a C 6 -C 18 aryl substituted with an R' 3 group, -C -O-R' 3; -O-R' 3, -S-R' 3 and -C -N -R' 3 with R' 3 a C 1 -C 30 alkyl group, the molar percentage of monomer M1 of formula in the random copolymer A1 ranging from 1 to 30%, and the molar percentage of monomer comprising boronic ester functions in random copolymer A2 ranging from 0.25 to 20%. - R 2 is selected from the group formed by -H, -CH 3 and -CH 2 -CH 3, - R 3 is selected from the group formed by a C 6 -C 18 aryl, a C 6 -C 18 aryl substituted with an R' 3 group, -C -O-R' 3; -O-R' 3, -S-R' 3 and -C -N -R' 3 with R' 3 a C 1 -C 30 alkyl group,