Controlling Internal Pore Sizes in Bicontinuous Polymeric Nanospheres

Beulah E Mckenzie,Simon J Holder,Heiner Friedrich,Maarten J M Wirix,Joël F De Visser,Paul H H Bomans,Fabio Nudelman,Nico A J M Sommerdijk,Olivia R Monaghan

doi:10.1002/ange.201408811

Beulah E Mckenzie, Simon J Holder + Show 7 more

Open Access

https://doi.org/10.1002/ange.201408811

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Abstract

AbstractComplex polymeric nanospheres were formed in water from comb‐like amphiphilic block copolymers. Their internal morphology was determined by three‐dimensional cryo‐electron tomographic analysis. Varying the polymer molecular weight (MW) and the hydrophilic block weight content allowed for fine control over the internal structure. Construction of a partial phase diagram allowed us to determine the criteria for the formation of bicontinuous polymer nanosphere (BPN), namely for copolymers with MW of up to 17 kDa and hydrophilic weight fractions of ≤0.25; and varying the organic solvent to water ratio used in their preparation allowed for control over nanosphere diameters from 70 to 460 nm. Significantly, altering the block copolymer hydrophilic–hydrophobic balance enabled control of the internal pore diameter of the BPNs from 10 to 19 nm.

Highlights

0.25; and varying the organic solvent to water ratio used in their preparation allowed for control over nanosphere diameters from 70 to 460 nm
We have shown in earlier work that encapsulation and temperature-controlled release of hydrophobic fluorescent molecules solvated in the PODMA domains can be achieved with poly(ethylene oxide)-b-poly(octadecyl methacrylate) (PEO-b-PODMA) bicontinuous polymer nanosphere (BPN).[7a]. BPNs show promise for use as templates for the formation of mesoporous materials, because the pores are accessible from the external aqueous medium[7c] and can potentially be infiltrated by aqueous mineral precursor to template the mineral growth.[8]
The internal morphologies were analyzed and resolved by 3D imaging using cryo-electron tomography, and the resulting partial phase diagram showed that BPNs form at relatively low molecular weight (MW) ( 17 kDa) and PEO content (f 0.25)

Summary

Introduction

0.25; and varying the organic solvent to water ratio used in their preparation allowed for control over nanosphere diameters from 70 to 460 nm. Simulations predict that it should be possible to tune the internal morphology of these nanospheres by changing the hydrophilic–hydrophobic balance of the block copolymer through variation of the PEO weight fraction (f) of the polymer.[11]

Results

Conclusion