Lattice Formation of Peripherally Charged Star Polymers in Aqueous Solution

Abstract

Functionalized poly(ethylene oxide) (PEO) stars (arm number f = 37−149) possessing peripheral tertiary amino groups were prepared by organized polymerization using macromonomers. Subsequently, positive charges were introduced into such peripheral tertiary amino groups by quaternization with methyl iodide. The structural ordering of these functionalized and peripherally charged stars was investigated through small-angle X-ray scattering in aqueous solution. PEO stars without charges (f > 72) formed a body-centered-cubic (bcc) structure near the overlap threshold (C*). On the other hand, peripherally charged PEO stars (f > 37) formed a lattice of bcc even below C*. The results indicate that ionization (electric double layer) of stars results in interparticle interactions giving rise to ordering. These interactions were screened by adding inorganic salt (KI).

Architecture of Polymeric Superstructures Constructed by Mesoscopically Ordered Cubic Lattices

“…The packing structure in the bulk film was determined using three-dimensional observation with the tilted method of TEM. [57] As mentioned above star-shaped polymers [47,48] lead to similar structure transitions. It was found that the measured near-neighbor distance of the spheres (D 0 ) for star polymers was proportional to the À0.32 th power of the polymer concentration which fits well the À1/3 power expected for a homogeneous system.…”

“…This self-segregation or self-micellization tends to create significant concentration fluctuations at the core-shell interface. Highly branched polymers such as star-shaped polymers [13,47,48] and (AB) n star block copolymers [49][50][51][52][53] lead to hierarchical structure transitions of cubic lattices during film formation, to minimize the thermodynamic energy. These branched polymers form a lattice of BCC structure near C*.…”

Diffusional behavior of multi-arm star polymers by 1H pulsed field gradient spin-echo NMR method

“…In general, this packing pattern appears in the lattice of not only simple cubic but also bcc structures. As mentioned in the Section 1, the stars with multiarm were packed in the lattice of a bcc structure near C* [5,6]. The conformation of star-shaped p(tBMA) can be regarded as similar to such star in solution.…”

“…Subsequently, positive charges were introduced into such peripheral tertiary amino groups by quarternization with methyl iodide (CH 3 I). It was found that these peripherally charged stars (fO37) formed a lattice of BCC below C* due to the electrostatic repulsion between stars [6].…”

Synthesis and characterization of star-like microgels by one-pot free radical polymerization

“…Star-shaped polymers are known to exhibit properties such as good solubility in common organic solvents and much lower solution viscosities compared to linear polymers of comparable molecular weights [1][2][3]. These unique properties have made them useful in applications ranging from drug delivery [4], membrane formation [5], or as additives in adhesives, paints and coatings [6].…”