Abstract
A versatile approach towards porous polystyrene-based frameworks functionalized with triazolyl moieties is reported. These porous materials were prepared from poly(D,L-lactic acid)-block-poly(styrene-stat-4-azidomethylstyrene) (PLA-b-P(S-stat-4-AMS)) diblock copolymer precursors. Upon macroscopic orientation and subsequent alkaline hydrolysis of the PLA block, such triazolyl-containing porous polystyrenes were produced. Experimentally, a PLA macroinitiator was synthesized by ring-opening polymerization (ROP) of D,l-lactide using a heterobifunctional initiator. The prepared macroinitiator containing a terminal tertiary α-bromo ester group allowed for further ATRP statistical copolymerization of styrene and 4-azidomethylstyrene, affording the second block, i.e. the P(S-stat-4-AMS) block. The styrene to 4-azidomethylstyrene molar ratio was tuned to obtain various compositions of the hydrophobic block. PLA macroinitiators and corresponding PLA-b-P(S-stat-4-AMS) diblock copolymers were fully characterized by size exclusion chromatography (SEC), 1H and 13C nuclear magnetic resonance (NMR), Fourier Transform Infrared (FT-IR) spectroscopy, and differential scanning calorimetry (DSC). Functionalization of PLA-b-P(S-stat-4-AMS) diblock copolymers with p-tolylacetylene or 2-methyl-3-butyn-2-ol was carried out via copper-catalyzed azide-alkyne cycloaddition (CuAAC), yielding triazole ring in high yields (>90%). Finally, the porous structure of such functional polystyrene frameworks was examined by scanning electron microscopy (SEM).
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