Syndiotactic Polyallyltrimethylsilane-Based Stereoregular Diblock Copolymers: Syntheses and Self-Assembled Nanostructures

Abstract

Structurally well-defined stereoregular diblock copolymers composed of syndiotactic polyallyltrimethylsilane (sPATMS) and poly­(methyl methacrylate) (PMMA) were prepared by using an α-bromoester-terminated sPATMS macroinitiator, which was chain extended by MMA using a cuprous halide-based atom transfer radical polymerization (ATRP) system. The α-bromoester-terminated sPATMS macroinitiator was prepared via the esterfication of hydroxyl-capped sPATMS with α-bromoisobutyryl bromide. The hydroxyl-capped sPATMS was generated via a selective chain transfer reaction to triethylaluminum (TEA) during the syndiospecific polymerization of allyltrimethylsilane (ATMS) conducted in the presence of syndiospecific ansa-metallocene catalysts. The proposed synthetic route not only offers the high-yield production of stereoregular sPATMS-b-PMMA but also provides the linking of the stereoregular block (sPATMS) with PMMA through a controlled/living radical polymerization process. Moreover, the proposed method offers effective control over the block chain length, the molecular weight distribution (M w/M n) and the stereoregularity of sPATMS block. Thus, the self-assembly of the resultant diblock copolymers produces well-ordered nanostructures from microphase separation, as evidenced by transmission electron microscopy and small-angle X-ray scattering results.

Sub-5 nm Domains in Ordered Poly(cyclohexylethylene)-block-poly(methyl methacrylate) Block Polymers for Lithography

“…Initiation and propagation of MMA on the PCHE-BiBB macroinitiator proceeded rapidly within the first 5 h, but complete initiation never occurred even up to 19 h of reaction time (Figure SI-6). Similar issues have been reported for ATRP of MMA with macroinitiator-based systems. ,− Regardless of the conditions used, all the ATRP products recovered contained unreacted macroinitiator which was affectively removed through Soxhlet extraction (Figure SI-7) with hexanes or pentane to give a small library of PCHE–PMMA samples with low values of molar mass dispersity (Table ). Figure shows overlaid SEC chromatograms for each PCHE–PMMA block copolymer after extraction along with the corresponding PCHE-BiBB precursors as evidence for successful removal of unreacted macroinitiator.…”

“…The procedure for functionalization of PCHE-OH with BiBB was similar to that described by Lee et al In this case, cyclohexane was used, which caused a majority of the TEA-HBr byproduct to crash out of solution. After completion, the salts were removed by filtration through a 0.45 μm HVHP Millipore membrane.…”

Control of Nanostructural Dimension by Crystallization in a Double-Crystalline Syndiotactic Poly(4-methyl-1-pentene)-block-poly(l-lactide) Block Copolymer

“…The s PMP–PLLA was prepared in two steps. First, hydroxyl-capped s PMP was synthesized by syndiospecific polymerization of 4-methyl-1-pentene conducted in the presence of triethylaluminum (chain transfer agent) using Me 2 C(Cp)(Flu)ZrCl 2 /MAO as a catalyst. − The resulting aluminum-capped s PMP was in situ treated with O 2 /H 2 O to provide the hydroxyl-capped s PMP. Second, the s PMP–PLLA was synthesized by ring-opening polymerization of l -lactide using tin(II) octoate as the catalyst and hydroxyl-capped s PMP as the macroinitiator.…”

Pattern transfer using block copolymers

“…Moreover, the authors reported that both the size and the periodicity of the PDMS domains could be tuned depending on the degree of swelling during solvent vapour annealing [140]. A polyallyltrimethylsilane-block-poly(methyl methacrylate) (sPATMS-b-PMMA) BCP was prepared by using an α-bromoester-terminated sPATMS macroinitiator, which was chain extended by MMA using a cuprous halide-based atom transfer radical polymerization (ATRP) [141] [62]. PLA-b-PDMS is another candidate to obtain small feature sizes since its incompatibility also is larger than that of PS-b-PDMS.…”