Controlled ATRP Synthesis of Novel Linear-Dendritic Block Copolymers and Their Directed Self-Assembly in Breath Figure Arrays

Xin Liu; Tina Monzavi; Ivan Gitsov

doi:10.3390/polym11030539

Controlled ATRP Synthesis of Novel Linear-Dendritic Block Copolymers and Their Directed Self-Assembly in Breath Figure Arrays

Polymers (Basel). 2019 Mar 21;11(3):539. doi: 10.3390/polym11030539.

Authors

Xin Liu¹, Tina Monzavi^{2

3}, Ivan Gitsov^{4

5}

Affiliations

¹ Department of Chemistry, State University of New York⁻College of Environmental Science and Forestry, Syracuse, NY 13210, USA. xliu70@syr.edu.
² Department of Chemistry, State University of New York⁻College of Environmental Science and Forestry, Syracuse, NY 13210, USA. tmonzavi@email.sc.edu.
³ Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA. tmonzavi@email.sc.edu.
⁴ Department of Chemistry, State University of New York⁻College of Environmental Science and Forestry, Syracuse, NY 13210, USA. igivanov@syr.edu.
⁵ The Michael M. Szwarc Polymer Research Institute, Syracuse, NY 13210, USA. igivanov@syr.edu.

Abstract

Herein, we report the formation and characterization of novel amphiphilic linear-dendritic block copolymers (LDBCs) composed of hydrophilic dendritic poly(ether-ester), PEE, blocks and hydrophobic linear poly(styrene), PSt. The LDBCs are synthesized via controlled atom transfer radical polymerization (ATRP) initiated by a PEE macroinitiator. The copolymers formed have narrow molecular mass distributions and are designated as LGn-PSt M_n, in which LG represents the PEE fragment, n denotes the generation of the dendron (n = 1⁻3), and M_n refers to the average molecular mass of the LDBC (M_n = 3.5⁻68 kDa). The obtained LDBCs are utilized to fabricate honeycomb films by a static "breath figure" (BF) technique. The copolymer composition strongly affects the film morphology. LDBCs bearing acetonide dendron end groups produce honeycomb films when the PEE fraction is lower than 20%. Pore uniformity increases as the PEE content decreases. For LDBCs with hydroxyl end groups, only the first generation LDBCs yield BF films, but with a significantly smaller pore size (0.23 μm vs. 1⁻2 μm, respectively). Although higher generation LDBCs with free hydroxyl end groups fail to generate honeycomb films by themselves, the use of a cosolvent or addition of homo PSt leads to BF films with a controllable pore size (3.7⁻0.42 μm), depending on the LDBC content. Palladium complexes within the two triazole groups in each of the dendron's branching moieties can also fine-tune the morphology of the BF films.

Keywords: ATRP; amphiphilic; breath figure; linear-dendritic copolymer; self-assembly.

Abstract

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