Golf Ball-like Particles Research Articles

Depletion-interaction-driven assembly of golf ball-like particles for development of colloidal macromolecules

Colloidal molecules created by clustering monodisperse particles are a significant model system of atoms and molecules in colloidal scale. To attain modelling of complex or high-molecular-weight molecules such as hyper-branched polymers and proteins, it is required to develop a new assembling system which can prepare three-dimensionally designed colloidal molecules. In this study, we proposed an approach for complex colloidal molecules created by association between golf ball-like particles and spherical particles via depletion interaction. Several golf ball-like particles joined together, which formed joined particle assemblies at the spherical particles acting as their joints in a depletant solution. The number of golf ball-like particles in a particle assembly was increased by increasing the concentration of the depletant, leading to the formation of branched colloidal chains of the golf ball-like particles. Because the golf ball-like particles in the colloidal chain flexibly rotated at their joints, the conformation of the chains varied in the depletant solution. The present results demonstrated that the golf-ball like particle that can be joined to form colloidal macromolecules with high association number and high flexibility will be a promising building block for complex colloidal model systems.

Facile Method to Synthesis of Golf Ball-Like Particles via Early-Ceased Seeded Dispersion Polymerization

Golf ball-like poly(methyl methacrylate) particles were produced via seeded dispersion polymerization of 2-ethylhexyl methacrylate with poly(methyl methacrylate) seed beads in the presence of saturated hydrocarbon droplets and evaporation of the hydrocarbon after the polymerization. It was observed that the particles are acquired in the form of a stable dispersion if the reaction is ceased around 42% of monomer conversion. Moreover, the effect of different reaction conditions (e.g. hydrocarbon and stabilizer type, initiator and monomer content, and polarity of the medium) on the shape and stability of the produced particles was investigated. It was revealed that the number and size of the dents on the surface of the golf ball-like particles could be manipulated easily with a simple change in each one of the parameters referred to above. In addition, the experimental results showed that some of the particles become unstable and diffuse into each other during polymerization, resulting in the formation of huge golf ball-like objects. The production of disk-like poly(methyl methacrylate) particles via fully developed seeded dispersion polymerization in the presence of a hydrocarbon which owns lengthy alkyl chain was another interesting finding of this study.

Imprinting Dimples on Narrowly Dispersed Polymeric Spheres by Heterocoagulation between Hard Polymer Particles and Soft Oil Droplets.

Golf ball-like particles having a number of dimples on their spherical surfaces were prepared by a combined method of heterocoagulation between hard polymer particles and soft silicone oil droplets, polymerization of the oil droplets, and dissolution of the polymer particles with tetrahydrofuran. In the heterocoagulation, polystyrene (PSt) particles of three different sizes were employed as hard particles. Distribution of dimples formed with small-sized PSt particles was less homogeneous than that with middle-sized PSt particles (MPS). Narrowly dispersed golf ball-like particles with homogeneously distributed dimples were successfully prepared with a high number ratio of MPS to oil droplets. The employment of large-sized PSt particles in the heterocoagulation decreased the number of PSt particles required for the stabilization of the oil droplets, which created polyhedron-like particles having dimples on their surface. Additional experiments in which polymer particles with different surface affinities to the oil droplets were heterocoagulated with the droplets revealed that a high surface affinity of particles to the droplets could deeply embed the polymer particles into the droplets and form dimples with a low contact angle.

Golf ball-like particles fabricated by nonsolvent/solvent-induced phase separation method

Monodisperse poly(styrene-co-acrylic acid) (P(S-co-AA)) particles having a “golf ball-like” shape were prepared by nonsolvent/solvent-induced phase separation process. The method is simple and easy operation. The nonsolvent/solvent phase was mixture of butanol, n-heptane and toluene. The dimpled surface comes from the aggregation of oil droplets on the surface of polymer spheres. The dimple’s morphology can be controlled by the polymer templates, dispersion medium, reaction time, and temperature. Reverse Pickering emulsion model was suggested for the formation of golf ball-like particles.

Effects of properties of the surface layer of seed particles on the formation of golf ball-like polymer particles by seeded dispersion polymerization

Micrometer-sized, monodisperse polystyrene (PS)/poly(styrene-co-sodium styrene sulfonate) (P(S-NaSS))/poly(n-butyl methacrylate) (Pn-BMA) composite particles having a ‘golf ball-like’ shape were prepared by seeded dispersion polymerization of n-butyl methacrylate with PS-core/P(S-NaSS)-shell seed particles with various shell thicknesses in the presence of dodecane droplets in a methanol/water (80/20, w/w) medium, followed by evaporation of the dodecane. The effects of the hydrophilic P(S-NaSS)-shell properties of seed particles on the formation of golf ball-like particles were investigated on the basis of thermodynamic and kinetic considerations. The dimples at the surface formed by the volume reduction of Pn-BMA/dodecane domains were deep when PS/P(S-NaSS) seed particles, the hydrophilic shell of which was thick, were used, whereas PS/P(S-NaSS)/Pn-BMA composite particles, the P(S-NaSS) hydrophilic shell of which was thin, exhibited a polyhedral shape. This is attributed to the fact that the molecular weight of the shell moiety comprising P(S-NaSS) was reduced by lowering the monomer concentration to decrease shell thickness, which seems to result in an increase in the mobility of Pn-BMA/dodecane domains at the particle surface. On the basis of this finding, when the molecular weight of the shell moiety of the seed particle was increased, golf ball-like particles were formed, even if the shell thickness of seed particles was thin. Micrometer-sized, monodisperse polystyrene (PS)/poly(styrene-cosodium styrene sulfonate) (P(S-NaSS))/poly(n-butyl methacrylate)(Pn-BMA) composite particles having a ‘golf ball-like’ shape were prepared by seeded dispersion polymerization of n-BMA with PS-core/P(S-NaSS)-shell seed particles in the presence of dodecane droplets. The effect of the P(S-NaSS)-shell properties of seed particles on the formation of golf ball-like particles was investigated. We clarified that golf ball-like particles could be obtained by proper selection of the hydrophilicity and molecular weight of the shell moiety.

Effect of Polymer Polarity on the Shape of “Golf Ball-like” Particles Prepared by Seeded Dispersion Polymerization

Micrometer-sized, monodisperse, ”golf ball-like” particles that have numerous dimples at the surfaces were prepared by seeded dispersion polymerization of n-butyl methacrylate (n-BMA), with polystyrene/poly(styrene-co-sodium styrene sulfonate) composite particles as seed, in the presence of dodecane droplets in a methanol/water (80/20, w/w) medium, followed by the evaporation of dodecane. The dimples at the surface were formed by the volume reduction of poly(n-BMA)/dodecane (Pn-BMA/dodecane) domains, because of the evaporation of the dodecane. The size and number of dimples at the surfaces of the obtained golf ball-like particles decreased as the sodium styrene sulfonate content of the seed particles increased. The Pn-BMA/dodecane domains were engulfed deeper in the surface layer of the seed particle, and, thus, dimples became apparently smaller at the surface with an increase in the hydrophilicity of the surface of the seed particle.