Poly(l-lactide) comb polymer brushes on the surface of clay layers

Poly(l-lactide) (PLLA) comb polymers on poly(hydroxyethyl methacrylate) (PHEMA) backbone were prepared on the surface of clay layers by a combination of in situ atom transfer radical polymerization (ATRP) and ring-opening polymerization. An ATRP initiator with a quaternary ammonium salt end group was intercalated into the interlayer spacing of clay. PHEMA polymer brushes on the surface of clay layers were prepared by in situ ATRP. PLLA comb polymers on PHEMA backbone were prepared by ring-opening polymerization. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results showed that with the increase of comb chain length more and more exfoliated structure was created. Aggregation of wormlike comb polymer brushes on the surface of clay layers was observed by TEM. Differential scanning calorimeter (DSC) results indicated that both the melting points and glass transition temperatures of the comb polymer brushes increase with the increase of comb chain length. The equilibrium melting temperature of the comb polymer brush on the surface of clay layers is lower than cleaved polymer. An atomic force microscopy (AFM) image proves the formation of wormlike structure by cleaved comb polymers.