A polynucleotide delivery vehicle comprising a modified polymer is provided herein, the modified polymer having the following formula: in which W1, W2, W3, W4, W5, W6, Z1, Z2, Z3, Z4, Z5, Z9, R1, R2, R3, R4, R5, n1, n2, n3, n4, n5, and n6 are defined herein. Also disclosed are methods of delivering a polynucleotide to the cytoplasm of a selected tissue type or cell type and methods of reducing expression of a gene in a cell or a subject in need thereof with the modified polymer.
