To increase number of labile sites on PVC and thus facilitate grafting from PVC by aids of free radical polymerization (FRP) under mild conditions

self-initiated

or bi-isopropyl thioxanthone (BIITX) and isopropylthioxanthone (ITX) initiated FRP of vinyl chloride (VC) in THF at 0℃ or 20℃ was carried out under UV irradiation.Influences of monomer concentration

incident light intensity

reaction time and temperature on monomer conversion

polymer molecular weight and its distribution were investigated. Radical ITX produced by dissociation of BIITX or by H abstraction of ITX from monomer could combine with a macroradical. This allowed ITX residues to be incorporated onto PVC via weak CC bonds which could be cleaved easily to regenerate radicals under UV light or heat stimuli

and thus yielded new labile sites on PVC for initiation. UV-Vis

1H-NMR and FTIR spectra analyses demonstrated the presence of labile chlorines and ITX residues on the resultant PVC

and indicated that PVC resulted from self-initiated or ITX initiated FRP contained great labile sites. Using the PVC as a macroinitiator

grafting polymerization of N

N-dimethylaminoethyl methacrylate (DMAEMA) in THF at 50℃ was started

and PVC-based graft copolymer (PVC-g-PDMAEMA) was synthesized. Compared with the initial PVC used

the graft copolymer achieved an increased molecular weight and narrowed molecular weight distribution.1H-NMR and FTIR analyses further confirmed the formation of PVC-based graft copolymer

and revealed that more labile chlorines or ITX residues on PVC favored initiation of graft polymerization. SEM and TEM observations showed that the graft copolymers containing more than 15 mol% (analyzed by 1H-NMR) of PDMAEMA segments could assemble into stable core-shell micelles in water (pH 3).The grafted hydrophilic PDMAEMA stretched towards aqueous media

forming the shell

while hydrophobic PVC portion coiled up to the core. This phenomenon suggested an amphiphilicity of the graft copolymers. In contrast

the copolymer with less content (only 0.15%) of grafted PDMAEMA could not form micelles due to its insufficient amphiphilicity.