Polymerizable composition comprising reactive silsesquioxane compound and aromatic vinyl compound

A polymerizable composition comprising:

• (a) 100 parts by mass of a reactive silsesquioxane compound, which is a polycondensate of an alkoxy silicon compound A of formula [1] and an alkoxy silicon compound B of formula [2]:
• Ar1—Si(OR1)3 [1]
• wherein Ar1 is a phenyl group having at least one group with a polymerizable double bond, a naphthyl group having at least one group with a polymerizable double bond, or a biphenyl group having at least one group with a polymerizable double bond;
• and R1 is methyl group or ethyl group;
• Ar2—Si(OR2)3 [2]
• wherein Ar2 is a phenyl group optionally substituted with a C1-6 alkyl group, a condensed polycyclic aromatic hydrocarbon group optionally substituted with a C1-6 alkyl group, or a hydrocarbon ring assembly group optionally substituted with a C1-6 alkyl group in which a plurality of aromatic rings are directly joined by a single bond;
• and R2 is methyl group or ethyl group;
• (b) 10 to 500 parts by mass of a fluorene compound of formula [3]:
• wherein R3 and R4 are each independently a hydrogen atom or methyl group;
• L1 and L2 are each independently a phenylene group optionally having a substituent or a naphthalenediyl group optionally having a substituent;
• L3 and L4 are each independently a C1-6 alkylene group;
• and m and n are each zero or a positive integer such that m+n is 0 to 40;
• and
• (c) 1 to 100 parts by mass of an aromatic vinyl compound of formula [4]:
• wherein R5 is a hydrogen atom or methyl group;
• L5 is a single bond, a hydrogen atom, an oxygen atom, a C1-20 aliphatic hydrocarbon residue having a valence of q optionally substituted with phenyl group, or a C1-20 aliphatic hydrocarbon residue having a valence of q optionally containing an ether bond;
• Ar3 is an aromatic hydrocarbon residue having a valence of p+1;
• p's are each independently 1 or 2;
• and q is an integer from 1 to 3 with the proviso that q is 1 when L5 is a hydrogen atom, and q is 2 when L5 is a single bond or an oxygen atom.