Dispersion Copolymerization of n-Butyl Methacrylate with Poly(ethylene oxide) Macromonomers in Methanol-Water. Comparison of Experiment with Theory

Abstract

The dispersion copolymerization of n-butyl methacrylate (BMA) in methanol-water media has been investigated. The reactions were carried out in the presence of a series of poly(ethylene oxide) (PEO) macromonomers(1) (Ci-EO"-(CH2)m-S), with a p-alkylstyrene (S) end group, with m = 1,4, and 7 and = 53 and 110. Nearly monodisperse PBMA latex particles from 90 to 500 nm in diameter are obtained. Factors which affect the particle size are the structure and molecular weight of the macromonomers, initial BMA, initiator, and macromonomer concentrations, temperature, and the composition of the solvent. The particle radius (R) follows the relationship R = [ ] 0•82±0 06-[macromonomer]o_0 54±0 03n_0 30±0 02[initiator]o_010±0 01. The power law exponents are close to those predicted from a coagulative nucleation model, particularly the multibin kinetics model for coalescence among unstabilized particles developed by Paine [Macromolecules 1990, 23, 3109]. R is also found to decrease with an increase in temperature and also with an increase in m (in 1). R, however, also increases with an increasing volume fraction of water in the reaction medium. The mechanism for the dispersion copolymerization is discussed in detail.

Thermosensitive Behavior of Poly(N-isopropylacrylamide) Grafted Polystyrene Nanoparticles

“…The larger particles can be obtained when the lower macromonomer concentration was used, the smaller ones, however, were prepared by using the higher initiator concentration at the given concentrations of macromonomer and comonomer. 23,24,27 Followed by the obtained S1-1 nanoparticle condition, S1-2 sample was then prepared by both decreasing the macromonomer concentration and increasing the initiator (AIBN) concentration. Furthermore, the smaller nanoparticles were also synthesized by using a higher polymerization temperature.…”

“…Furthermore, the smaller nanoparticles were also synthesized by using a higher polymerization temperature. 23,24,27 Therefore, sample S1-3 was synthesized by both decreasing the macromonomer concentration and raising the polymerization temperature from 60 to 70 • C, based on preparing S1-2 condition. The characterizations of the resulting samples were shown in Table II.…”

“…We have known that the smaller particles were formed by using the higher molecular weight of macromonomer at the given concentration. 22,24,27 To prepare nanoparticles with similar diameters and different chain lengths on their surfaces, the lower concentration of PNIPAAm macromonomer will be used for the macromonomer having larger molecular weights. Thus, the contents of PNIPAAm segment on the nanoparticles will be different.…”

“…And, their particle sizes can be widely controlled via varying reaction parameters such as concentration of macromonomer, initiator and styrene, and polymerization temperature. [20][21][22][23][24][25][26][27][28] The hydrodynamic diameter of the nanoparticles consisting of a PSt core and grafted PNIPAAm chains on their surfaces was dependent on the temperature of the dispersion solution. 22 Thus, the grafted PNIPAAm chains showed the coil-to-globule transition at a LCST in our previous work.…”

Preparation of Micron-sized Monodisperse Poly (Styrene-co-methyl Methacrylate) Microspheres by Dispersion Copolymerization

“…To produce functional microspheres, one common strategy that is dispersion copolymerization has been extensively adopted [9][10][11][12][13][14][15]. However, some undesired results such as polydisperse particle sizes and coagulum were often observed when a small amount of cross-linking agent, dye-comonomer, or even hydrophilic monomers were present at the start of polymerization [16][17][18][19][20][21].…”