Graft copolymers via combination of cationic polymerization and atom transfer radical polymerization and their phase separation into spherical/worm-like nanostructures

Poly(p-chloromethyl styrene)-graft-poly(methyl methacrylate) (PCMS-g-PMMA) and poly(p-chloromethyl styrene)-graft-poly(benzyl methacrylate) (PCMS-g-PBzMA) graft copolymers with asymmetric branches are synthesized via the combination of cationic polymerization and atom transfer radical polymerization (ATRP). The process involves first, the preparation of poly(p-chloromethyl styrene) (PCMS-CH2Cl) macroinitiator without any cross-linking or side reactions through pendant benzyl chloride (−CH2Cl) functionality by cationic polymerization using a simple FeCl3-based initiating system at 25 °C. The as-synthesized PCMS-CH2Cl, without any transformation, is then used as the macroinitiator to graft PMMA and PBzMA branches by ATRP to produce PCMS-g-PMMA and PCMS-g-PBzMA graft copolymers of varying compositions with controlled molecular weight and moderately narrow polydispersities (M w/M n ≤ 1.32). The resulting PCMS21 -g-PMMA232 graft copolymer in thin film form phase separates into spherical morphology with an average diameter of 170 ± 72 nm. Whereas the PCMS21 -g-PBzMA156 graft copolymer gives worm-like nanostructures with an average length of 94 nm and width of 31 nm due to phase separation as visualized through atomic force microscopy. On the other hand, the phase-separated morphology is not very well-defined for other graft copolymers (PCMS113 -g-PMMA227 and PCMS113 -g-PBzMA154) thin films containing longer PCMS chains. This approach represents a rapid and convenient route to prepare unique spherical/worm-like polymer nanostructures.