For the first time, a true step-growth polymerization, i.e, polyesterification, was achieved by a
photochemical means. Thus, heterobifunctional monomers, namely benzodioxinone and naphthodioxinone
compounds possessing both chromophoric and aliphatic hydroxyl groups in the structure (HDPD and HDNP,
respectively), were synthesized by a ring closure and subsequent etherification processes and characterized.
Photolysis of these compounds in CH2Cl2 at λinc = 300 nm yielded oligoesters with narrow molecular weight
distribution. In the case of HDNP, photolysis can be performed at higher wavelengths, e.g., at λinc = 350 nm,
because of the extended absorption introduced by the naphthalene ring. The structure of the photochemically
formed oligoester was confirmed by FT-IR and 1H NMR spectral measurements.
Synthesis of graft copolymers by combination of atom transfer radical polymerization (ATRP) and photoinduced reaction of benzodioxinone was reported. First, statistical copolymers of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) were prepared by ATRP process. Then, the other component, namely benzodioxinone functional polystyrene (PS-B) was prepared independently by the etherification reaction of hydroxyl benzodioxinone (HDPD) with polystyrene (PS-Br) obtained by ATRP by using K 2 CO 3 in acetone. Photolysis of poly(hydroxyethyl methacrylate-co-methyl methacrylate) (P(HEMA-co-MMA)) and (PS-B) prepolymers in CH 2 Cl 2 at λ inc > 300 nm yielded graft copolymers. The graft copolymers and the intermediates were characterized in detail by using 1 H NMR, GPC, UV, FT-IR, DSC, and AFM measurements.
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