Synthesis and Self-Assembly of Amphiphilic Triblock Terpolymers with Complex Macromolecular Architecture

Two star triblock terpolymers (PS-<i>b</i>-P2VP-<i>b</i>-PEO)₃ and one dendritic-like terpolymer [PS-<i>b</i>-P2VP-<i>b</i>-(PEO)₂]₃ of PS (polystyrene), P2VP (poly­(2-vinylpyridine)), and PEO (poly­(ethylene oxide)), never reported before, were synthesized by combining atom transfer radical and anionic polymerizations. The synthesis involves the transformation of the −Br groups of the previously reported Br-terminated 3-arm star diblock copolymers to one or two −OH groups, followed by anionic polymerization of ethylene oxide to afford the star or dendritic structure, respectively. The well-defined structure of the terpolymers was confirmed by static light scattering, size exclusion chromatography, and NMR spectroscopy. The self-assembly in solution and the morphology in bulk of the terpolymers, studied by dynamic light scattering and transmission electron microscopy, respectively, reveal new insights in the phase separation of these materials with complex macromolecular architecture

Non-Covalent PS–SC–PI Triblock Terpolymers <i>via</i> Polylactide Stereocomplexation: Synthesis and Thermal Properties

Polylactide (PLA) stereocomplexes (SCs) containing amorphous block copolymers have gained enormous interest due to their unique properties and wide range of potential applications. In this work, we report the synthesis and properties of non-covalent triblock terpolymers: polystyrene–SCPLA–polyisoprene (PS–SC–PI) via the stereocomplexation of PS-b-PDLA with PI-b-PLLA diblock copolymers through the solution-precipitation method. The diblock copolymers were prepared by combining the anionic polymerization high-vacuum technique with ring-opening polymerization (ROP). First, several well-defined ω-hydroxyl polystyrenes and polyisoprenes (PS-OH and PI-OH) with varied molecular weights were synthesized by anionic polymerization using sec-BuLi as the initiator. PS-OH and PI-OH were used as the macroinitiators for the ROP of DLA and LLA catalyzed by tin­(II) 2-ethyl hexanoate to afford PS-b-PDLA and PI-b-PLLA. PS–SC–PIs were prepared by mixing PS-b-PDLA and PI-b-PLLA solutions (in dichloromethane) and precipitated into methanol. The molecular characteristics of the block copolymers were determined by 1H NMR spectroscopy and size exclusion chromatography. The formation of PS–SC–PIs was evidenced by differential scanning calorimetry, X-ray diffraction, and Fourier-transform infrared, and circular dichroism spectroscopies. A preliminary study by atomic force microscopy reveals the thin-film phase behavior and the supramolecular organization of the PS–SC–PI

Poly(vinylidene fluoride)/Polymethylene-Based Block Copolymers and Terpolymers

Dual crystalline diblock copolymers consisting of polymethylene (PM) and poly­(vinylidene fluoride) (PVDF) blocks as well as triblock terpolymers with polystyrene (PS) as middle block were synthesized. For the synthesis, two/three different polymerization methods such as polyhomologation, atom transfer radical polymerization (ATRP), and iodine transfer polymerization (ITP) along with chain-end postpolymerization reactions were employed. Solid-state NMR spectroscopy revealed the characteristic peaks of all constituent blocks while gel permeation chromatography (GPC) results demonstrated the controlling/living nature of all implemented polymerization methods. The analysis of crystallization behavior based on differential scanning calorimetry (DSC) indicates the presence of different PVDF crystalline phases (α, β, and γ) n block copolymers. Further analysis with X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopies revealed the coexistence of α- and β-phases in diblock copolymers and β- and γ-phases in triblock terpolymer. An initial study of self-assembly in DMF, a selective solvent for PVDF and PS, was performed by dynamic light scattering (DLS) and atomic force microscopy (AFM)