Tuning the Chirality of Block Copolymers: From Twisted Morphologies to Nanospheres by Self‐Assembly |
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| Authors: | Silvia Suárez‐Suárez Prof. Gabino A. Carriedo Dr. Alejandro Presa Soto |
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| Affiliation: | Departmento de Química Orgánica e Inorgánica (IUQOEM), Universidad de Oviedo, Julián Clavería s/n, 33006, Oviedo (Spain), Fax: (+34)?985103446 |
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| Abstract: | New advances into the chirality effect in the self‐assembly of block copolymers (BCPs) have been achieved by tuning the helicity of the chiral‐core‐forming blocks. The chiral BCPs {[N?P(R)‐O2C20H12]200?x[N?P(OC5H4N)2]x}‐b‐ [N?PMePh]50 ((R)‐O2C20H12=(R)‐1,1′‐binaphthyl‐2,2′‐dioxy, OC5H4N=4‐pyridinoxy (OPy); x=10, 30, 60, 100 for 3 a – d , respectively), in which the [N?P(OPy)2] units are randomly distributed within the chiral block, have been synthesised. The chiroptical properties of the BCPs ([α]D vs. T and CD) demonstrated that the helicity of the BCP chains may be simply controlled by the relative proportion of the chiral and achiral (i.e., [N?P(R)‐O2C20H12] and [N?P(OPy)2], respectively) units. Thus, although 3 a only contained only 5 % [N?P(OPy)2] units and exhibited a preferential helical sense, 3 d with 50 % of this unit adopted non‐preferred helical conformations. This gradual variation of the helicity allowed us to examine the chirality effect on the self‐assembly of chiral and helical BCPs (i.e., 3 a – c ) and chiral but non‐helical BCPs (i.e., 3 d ). The very significant influence of the helicity on the self‐assembly of these materials resulted in a variety of morphologies that extend from helical nanostructures to pearl‐necklace aggregates and nanospheres (i.e., 3 b and 3 d , respectively). We also demonstrate that the presence of pyridine moieties in BCPs 3 a – d allows specific decoration with gold nanoparticles. |
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| Keywords: | block copolymers chirality effect helical structures phosphazenes self‐assembly |
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