Densely Heterografted Brush Macromolecules with Crystallizable Grafts. Synthesis and Bulk Properties

Poly(ethylene glycol) methyl ether methacrylate macromonomer (PEOMA, MW = 1100 g/mol, DP PEO = 23) and octadecyl methacrylate or acrylate (ODMA, ODA) were (co)polymerized by atom transfer radical polymerization (ATRP). The one-pot copolymerization via grafting through (macromonomer method) yielded densely heterografted copolymers (DP n = 300−500). The composition of the copolymers strongly depended on the selection of comonomer pairs; i.e., two methacrylates (PEOMA/ODMA) or methacrylate/acrylate (PEOMA/ODA) led to formation of a spontaneous random or gradient copolymer, respectively. The combination of hydrophilic and hydrophobic segments in the same polymer chain caused microphase segregation. Additionally, X-ray results indicated that frustration in packing the crystallizable segments, helical PEOMA and hexagonal ODMA crystals, can direct to an amorphous fraction instead of a semicrystalline ODMA in the graft copolymer. Thermomechanical measurements showed the soft rubbery behavior of the copolymers (10 4 > G ‘ > 10 3 Pa, G ‘ > G ‘ ‘). The synthesis of homopolymers with a high degree of polymerization is also reported (DP PPEOMA > 325, DP PODMA > 435, DP PODA > 150).