Process for the preparation of a progressive photoprotective silicon organic polymer, which comprises the reaction of a monomer of formula (I): ** Formula ** where: R is selected from the group consisting of (i), (ii), (iii) and (iv): ** Formula ** R1, R2, R3, R4 and R5 are independently selected from the group consisting of H, linear or branched (C1-C6) alkyl, (C3-C6) cycloalkyl, OR6 , NH2, NHR7, NR8R9, COOH, COOR10, CONH2, CONHR11, CONR12R13, SO2NH2, SO2NHR14 and SO2NR15R16； R6 is linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl； R7 is linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl； R8 is linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl； R9 is linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl； or R8 and R9 taken together with the nitrogen atom to which they are attached form a pyrrolidine, piperidine or morpholine ring； R10 is linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl； R11 is linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl； R12 is linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl； R13 is linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl； or R12 and R13 taken together with the nitrogen atom to which they are attached form a pyrrolidine, piperidine or morpholine ring； R14 is linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl； R15 is linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl； R16 is linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl, or R15 and R16 taken together with the nitrogen atom to which they are attached form a pyrrolidine, piperidine or morpholine ring； A is H, linear or branched (C1-C6) alkyl or (C3-C6) cycloalkyl, OR'1, NH2, NHR'2 or NR'3R'4； L is a single bond, -CH2-, or -CH2-CH (RL) - Z is NH or O； Ra is linear or branched (C1-C6) alkyl, linear or branched (C2-C6) alkenyl, (C3-C6) cycloalkyl or phenyl； Rb is linear or branched (C1-C6) alkyl, linear or branched (C2-C6) alkenyl, (C3-C6) cycloalkyl or phenyl； Rc is linear or branched (C1-C6) alkyl, linear or branched (C2-C6) alkenyl
