Persistent Micelle Corona Chemistry Enables Constant Micelle Core Size with Independent Control of Functionality and Polyelectrolyte Response

Abstract

Polymer micelles have found significant uses in areas such as drug/gene delivery, medical imaging, and as templates for nanomaterials. For many of these applications, the micelle performance depends on its size and chemical functionalization. To date, however, these parameters have often been fundamentally coupled since the equilibrium size of a micelle is a function of the chemical composition in addition to other parameters. Here, we demonstrate a novel processing pathway allowing for the chemical modification to the corona of kinetically trapped “persistent” polymer micelles, termed Persistent Micelle Corona Chemistry (PMCC). Judicious planning is crucial to this size-controlled functionalization where each step requires all reagents and polymer blocks to be compatible with (1) the desired chemistry, (2) micelle persistency, and (3) micelle dispersion. A desired functionalization can be implemented with PMCC by pairing the synthetic planning with polymer solubility databases. Specifically, poly­(cyclohexyl methacrylate-b-(diethoxyphosphoryl)­methyl methacrylate) (PCHMA-b-PDEPMMA) was prepared to combine a glassy-core block (PCHMA) for kinetic control with a block (PDEPMMA) that is able to be hydrolyzed to yield acid groups. The processing sequence determines the resulting micelle size distribution where the hydrolyzed-then-micellized sequence yields widely varying micelle dimensions due to equilibration. In contrast, the micellized-then-hydrolyzed sequence maintains kinetically trapped micelles throughout the PMCC process. Statistically significant transmission electron microscopy (TEM) measurements demonstrate that PMCC uniquely enables this functionalization with constant average micelle core dimensions. Furthermore, these kinetically trapped micelles also subsequently maintain constant micelle core size when modifying the Coulombic interactions of the micelle corona via pH changes.

Determination of Block Copolymer Micelle Core Tg Using 1H NMR Transverse (T2) Relaxation Measurements of Micelle Coronas

“…Therefore, micelles with lower corona grafting densities are expected to show a larger increase in the slope below T g , and this is indeed reflected in the PS–PEG samples. A similar effect would be expected if, for example, the molecular weight of the corona block was decreased or the corona chemistry was modified to be more hydrophobic …”

“…A similar effect would be expected if, for example, the molecular weight of the corona block was decreased or the corona chemistry was modified to be more hydrophobic. 45 The measured core T g values demonstrate a significant reduction in core T g compared to that of the bulk material. Figure 3 shows a comparison of the core T g of the PS domains and of the bulk T g values using the Flory−Fox equation.…”

Self-Assembly of Block Copolymers in Thin Films Swollen-Rich in Solvent Vapors

“…To the best of our knowledge, the hexagonal packing of P2VP 181 -b-PCHMA 643 micelles on solid surfaces was not reported until now. The only available reports are discussing some disordered micellar films of P2VP-b-PCHMA [80], eventually loaded with metallic nanoparticles [81], and other micellar films made of more or less similar PS-b-P2VP [74,77,82], polyisoprene-b-poly(2-vinylpyridine) (PI-b-P2VP) [83], or poly(cyclohexyl methacrylate-b-(diethoxyphosphoryl)methyl methacrylate) (PCHMA-b-PDEPMMA) [84]. Films covered with spherical structures made of poly(dimethylsiloxane)b-poly(2-vinylpyridine) (PDMS-b-P2VP) were also reported in the literature [85].…”

Understanding Rapid Intercalation Materials One Parameter at a Time

“…In contrast, PMT is based upon kinetic entrapment to sidestep the limitations of equilibrating micelles. [132,133] All but the most recent PMT literature [134,135] was recently reviewed comprehensively. [136] The material-to-template (M:T) ratio is an important parameter where increasing the amount of material precursors leads to expanded wall thickness with constant pore size and shape (Figure 4d-f).…”