Limits...
Precise hierarchical self-assembly of multicompartment micelles.

Gröschel AH, Schacher FH, Schmalz H, Borisov OV, Zhulina EB, Walther A, Müller AH - Nat Commun (2012)

Bottom Line: This directed self-assembly leads to a step-wise reduction of the degree of conformational freedom and dynamics and avoids undesirable kinetic obstacles during the structure build-up.It yields a general concept for homogeneous populations of well-defined multicompartment micelles with precisely tunable patchiness, while using simple linear ABC triblock terpolymers.We further demonstrate control over the hierarchical step-growth polymerization of multicompartment micelles into micron-scale segmented supracolloidal polymers as an example of programmable mesoscale colloidal hierarchies via well-defined patchy nanoobjects.

View Article: PubMed Central - PubMed

Affiliation: Makromolekulare Chemie II, Universität Bayreuth, Bayreuth, Germany.

ABSTRACT
Hierarchical self-assembly offers elegant and energy-efficient bottom-up strategies for the structuring of complex materials. For block copolymers, the last decade witnessed great progress in diversifying the structural complexity of solution-based assemblies into multicompartment micelles. However, a general understanding of what governs multicompartment micelle morphologies and polydispersity, and how to manipulate their hierarchical superstructures using straightforward concepts and readily accessible polymers remains unreached. Here we demonstrate how to create homogeneous multicompartment micelles with unprecedented structural control via the intermediate pre-assembly of subunits. This directed self-assembly leads to a step-wise reduction of the degree of conformational freedom and dynamics and avoids undesirable kinetic obstacles during the structure build-up. It yields a general concept for homogeneous populations of well-defined multicompartment micelles with precisely tunable patchiness, while using simple linear ABC triblock terpolymers. We further demonstrate control over the hierarchical step-growth polymerization of multicompartment micelles into micron-scale segmented supracolloidal polymers as an example of programmable mesoscale colloidal hierarchies via well-defined patchy nanoobjects.

Show MeSH

Related in: MedlinePlus

Spherical and linear MCMs formed by SBMs with various core volume ratios (VPS/VPB).MCMs were prepared by dialysis of subunits with mixed- or compartmentalized PS/PMMA corona and PB core in DMAc into acetone/isopropanol (60/40 v/v). Staining was achieved with OsO4 (PB black, PS grey, PMMA corona invisible). Subunits: (a) Weakly phase-segregated corona of PS and PMMA of SBM9 subunits with a PB core in DMAc. (b,c) DLS CONTIN plots of pre-assembled subunits and final MCMs of SBM3 and SBM9. MCMs: (d) SB2 (BSB) 'hamburgers' of SBM6; (e) SB3 'clovers' of SBM3; (f) SB4 'Maltese crosses' of SBM4; (g) SB7 'footballs' of SBM5; (h,i) SBx 'footballs' of SBM1 and SBM2. The inset (lower right, i) depicts the Fourier transform of the TEM micrograph. (j) SBSBS=(SBS)2 'double burgers' of SBM7 (see also Supplementary Fig. S3); (k) (SBS)x linear MCM colloidal polymers of SBM9. The kinks in the colloidal polymers will be discussed below (Scale bars are 200 nm and 50 nm in the insets).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3293418&req=5

f3: Spherical and linear MCMs formed by SBMs with various core volume ratios (VPS/VPB).MCMs were prepared by dialysis of subunits with mixed- or compartmentalized PS/PMMA corona and PB core in DMAc into acetone/isopropanol (60/40 v/v). Staining was achieved with OsO4 (PB black, PS grey, PMMA corona invisible). Subunits: (a) Weakly phase-segregated corona of PS and PMMA of SBM9 subunits with a PB core in DMAc. (b,c) DLS CONTIN plots of pre-assembled subunits and final MCMs of SBM3 and SBM9. MCMs: (d) SB2 (BSB) 'hamburgers' of SBM6; (e) SB3 'clovers' of SBM3; (f) SB4 'Maltese crosses' of SBM4; (g) SB7 'footballs' of SBM5; (h,i) SBx 'footballs' of SBM1 and SBM2. The inset (lower right, i) depicts the Fourier transform of the TEM micrograph. (j) SBSBS=(SBS)2 'double burgers' of SBM7 (see also Supplementary Fig. S3); (k) (SBS)x linear MCM colloidal polymers of SBM9. The kinks in the colloidal polymers will be discussed below (Scale bars are 200 nm and 50 nm in the insets).

Mentions: Dissolution of SBMs in DMAc (N,N-dimethylacetamide, non-solvent for PB, c=1 g l−1) yields spherical micelles with a PB core and a mixed or compartmentalized corona of PS and PMMA, termed subunits. This is the first reduction of the degrees of conformational freedom in the directed self-assembly process. Dynamic light scattering (DLS) confirms their formation with small hydrodynamic radii of Rh,app=9–14 nm (Fig. 3a–c, Supplementary Fig. S1 and Table S1)45. In a second step, to direct the structure formation, dialysis against an acetone/isopropanol mixture (60/40 v/v) triggers the collapse of the PS block within the corona and induces higher-level aggregation of the subunits into the final multicompartment-core micelles (MCMs, Fig. 1). Rearrangements and phase segregation between PS and PMMA occur during this process, equalling a refinement of the subunits. Acetone is a non-solvent for PB, a near-Θ solvent for PS and a good solvent for PMMA. Isopropanol is a near-Θ solvent for PMMA and a non-solvent for both PS and PB. Hence, PB remains insoluble at all times, its chains yet mobile enough to allow for rearrangements during the process of subunit aggregation into the final MCMs. The importance of a dynamic PB core is underscored by the fact that freezing the segmental dynamics of the subunits via crosslinking the PB core results in ill-defined MCMs (see Supplementary Fig. S2).


Precise hierarchical self-assembly of multicompartment micelles.

Gröschel AH, Schacher FH, Schmalz H, Borisov OV, Zhulina EB, Walther A, Müller AH - Nat Commun (2012)

Spherical and linear MCMs formed by SBMs with various core volume ratios (VPS/VPB).MCMs were prepared by dialysis of subunits with mixed- or compartmentalized PS/PMMA corona and PB core in DMAc into acetone/isopropanol (60/40 v/v). Staining was achieved with OsO4 (PB black, PS grey, PMMA corona invisible). Subunits: (a) Weakly phase-segregated corona of PS and PMMA of SBM9 subunits with a PB core in DMAc. (b,c) DLS CONTIN plots of pre-assembled subunits and final MCMs of SBM3 and SBM9. MCMs: (d) SB2 (BSB) 'hamburgers' of SBM6; (e) SB3 'clovers' of SBM3; (f) SB4 'Maltese crosses' of SBM4; (g) SB7 'footballs' of SBM5; (h,i) SBx 'footballs' of SBM1 and SBM2. The inset (lower right, i) depicts the Fourier transform of the TEM micrograph. (j) SBSBS=(SBS)2 'double burgers' of SBM7 (see also Supplementary Fig. S3); (k) (SBS)x linear MCM colloidal polymers of SBM9. The kinks in the colloidal polymers will be discussed below (Scale bars are 200 nm and 50 nm in the insets).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3293418&req=5

f3: Spherical and linear MCMs formed by SBMs with various core volume ratios (VPS/VPB).MCMs were prepared by dialysis of subunits with mixed- or compartmentalized PS/PMMA corona and PB core in DMAc into acetone/isopropanol (60/40 v/v). Staining was achieved with OsO4 (PB black, PS grey, PMMA corona invisible). Subunits: (a) Weakly phase-segregated corona of PS and PMMA of SBM9 subunits with a PB core in DMAc. (b,c) DLS CONTIN plots of pre-assembled subunits and final MCMs of SBM3 and SBM9. MCMs: (d) SB2 (BSB) 'hamburgers' of SBM6; (e) SB3 'clovers' of SBM3; (f) SB4 'Maltese crosses' of SBM4; (g) SB7 'footballs' of SBM5; (h,i) SBx 'footballs' of SBM1 and SBM2. The inset (lower right, i) depicts the Fourier transform of the TEM micrograph. (j) SBSBS=(SBS)2 'double burgers' of SBM7 (see also Supplementary Fig. S3); (k) (SBS)x linear MCM colloidal polymers of SBM9. The kinks in the colloidal polymers will be discussed below (Scale bars are 200 nm and 50 nm in the insets).
Mentions: Dissolution of SBMs in DMAc (N,N-dimethylacetamide, non-solvent for PB, c=1 g l−1) yields spherical micelles with a PB core and a mixed or compartmentalized corona of PS and PMMA, termed subunits. This is the first reduction of the degrees of conformational freedom in the directed self-assembly process. Dynamic light scattering (DLS) confirms their formation with small hydrodynamic radii of Rh,app=9–14 nm (Fig. 3a–c, Supplementary Fig. S1 and Table S1)45. In a second step, to direct the structure formation, dialysis against an acetone/isopropanol mixture (60/40 v/v) triggers the collapse of the PS block within the corona and induces higher-level aggregation of the subunits into the final multicompartment-core micelles (MCMs, Fig. 1). Rearrangements and phase segregation between PS and PMMA occur during this process, equalling a refinement of the subunits. Acetone is a non-solvent for PB, a near-Θ solvent for PS and a good solvent for PMMA. Isopropanol is a near-Θ solvent for PMMA and a non-solvent for both PS and PB. Hence, PB remains insoluble at all times, its chains yet mobile enough to allow for rearrangements during the process of subunit aggregation into the final MCMs. The importance of a dynamic PB core is underscored by the fact that freezing the segmental dynamics of the subunits via crosslinking the PB core results in ill-defined MCMs (see Supplementary Fig. S2).

Bottom Line: This directed self-assembly leads to a step-wise reduction of the degree of conformational freedom and dynamics and avoids undesirable kinetic obstacles during the structure build-up.It yields a general concept for homogeneous populations of well-defined multicompartment micelles with precisely tunable patchiness, while using simple linear ABC triblock terpolymers.We further demonstrate control over the hierarchical step-growth polymerization of multicompartment micelles into micron-scale segmented supracolloidal polymers as an example of programmable mesoscale colloidal hierarchies via well-defined patchy nanoobjects.

View Article: PubMed Central - PubMed

Affiliation: Makromolekulare Chemie II, Universität Bayreuth, Bayreuth, Germany.

ABSTRACT
Hierarchical self-assembly offers elegant and energy-efficient bottom-up strategies for the structuring of complex materials. For block copolymers, the last decade witnessed great progress in diversifying the structural complexity of solution-based assemblies into multicompartment micelles. However, a general understanding of what governs multicompartment micelle morphologies and polydispersity, and how to manipulate their hierarchical superstructures using straightforward concepts and readily accessible polymers remains unreached. Here we demonstrate how to create homogeneous multicompartment micelles with unprecedented structural control via the intermediate pre-assembly of subunits. This directed self-assembly leads to a step-wise reduction of the degree of conformational freedom and dynamics and avoids undesirable kinetic obstacles during the structure build-up. It yields a general concept for homogeneous populations of well-defined multicompartment micelles with precisely tunable patchiness, while using simple linear ABC triblock terpolymers. We further demonstrate control over the hierarchical step-growth polymerization of multicompartment micelles into micron-scale segmented supracolloidal polymers as an example of programmable mesoscale colloidal hierarchies via well-defined patchy nanoobjects.

Show MeSH
Related in: MedlinePlus