Summary: Free radical emulsion polymerization of styrene (S) or butyl acrylate (BA) in the presence of latices of linear polyethylene (PE) prepared by catalytic emulsion polymerization affords colloidally stable multiphase latices. Coagulation of a PE/PS latex affords nanocomposites composed of small PE phases dispersed in a PS matrix, as evidenced by the large supercoolings of PE crystallization (by DSC). TEM of PE/PBA latices indicates a PBA phase around the PE particles under the emulsion polymerization conditions investigated. Films formed from these dispersions exhibit homogeneously dispersed PE particles.
Multiphase latices are obtained by free radical emulsion polymerization of butyl acrylate in the presence of latices of linear polyethylene (PE) prepared by catalytic emulsion polymerization. 相似文献
Polystyrene/poly(butyl acrylate) PS/PBA polymer dispersions with core/shell particles functionalized by N‐methylol acrylamide (N‐MA) were prepared through two‐step emulsion polymerization. The influence of N‐MA situated in shell and/or in core/shell of particles on the crosslinking reaction was studied to relate its mechanical properties and organic solvent resistance of films cast from basic and modified PS/PBA latexes. The changes in the phase arrangement of functionalized and unfunctionalized films after treatment with solvent and annealing were monitored. It was found that at the presence of N‐MA the crosslinking reaction occured already during the polymerization. Films from functionalized dispersions exhibit improved tensile strength and higher resistance against organic solvent. 相似文献
This paper reports the preparation of cross-linked core-shell poly(butyl acrylate)/polystyrene (PBA/PS) and poly(butyl acrylate)/poly(methyl
methacrylate) (PBA/PMMA) nanoparticles via seeded emulsion polymerization and their application in nylon-based composites.
A highly cross-linked structure was formed in both the cores and the shells by using a cross-linking agent, which could prevent
the migration of hydrophobic PS shells to the inside of particles. There were covalent bonds on the interfaces between the
cores and the shells of both particles. The average particle sizes were 40–50 nm, and the size distributions were narrow.
The kinetics of polymerization was investigated. Well-defined core-shell structure and narrow particle size distribution could
be achieved under starved conditions of monomer feeding. Furthermore, PBA/PMMA particles were used to fill nylon 6, good dispersion
was obtained because of the strong interfacial interaction between the nanoparticles and the nylon 6 matrix and the good deformation
ability of nanoparticles, and the toughness and rigidity of the composites were improved evidently.
__________
Translated from Acta Polymerica Sinica, 2005, (6) (in Chinese) 相似文献
Monodispersed polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) composite particles having 9.4 μm in diameter were produced by seeded polymerization for the dispersion
of highly n-butyl methacrylate (BMA)-swollen PS particles, and their morphologies were examined. The highly BMA-swollen PS particles
(about 150 times the weight of the PS seed particles) were prepared by mixing monodispersed 1.8 μm-sized PS seed particles
and 0.7 μm sized BMA droplets prepared with an ultrasonic homogenizer in ethanol/water (1/2, w/w) medium at room temperature.
After NaNO2 aqueous solution as inhibitor was added in the dispersion, the seeded polymerization was carried out at 70 °C. In an optical
microscopic observation, one or two spherical high contrast regions which consisted mainly of PS were observed inside PS/PBMA
composite particles. In the PS domain, there were many fine spherical PBMA domains. Such morphologies were based on the phase
separation of PS and PBMA within the homogeneous swollen particles during the seeded polymerization.
Received: 04 June 1997 Accepted: 27 August 1997 相似文献
A series of polyacrylate‐polystyrene‐polyisobutylene‐polystyrene‐polyacrylate (X‐PS‐PIB‐PS‐X) pentablock terpolymers (X=poly(methyl acrylate) (PMA), poly(butyl acrylate) (PBA), or poly(methyl methacrylate) (PMMA)) was prepared from poly (styrene‐b‐isobutylene‐b‐styrene) (PS‐PIB‐PS) block copolymers (BCPs) using either a Cu(I)Cl/1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) or Cu(I)Cl/tris[2‐(dimethylamino)ethyl]amine (Me6TREN) catalyst system. The PS‐PIB‐PS BCPs were prepared by quasiliving carbocationic polymerization of isobutylene using a difunctional initiator, followed by the sequential addition of styrene, and were used as macroinitiators for the atom transfer radical polymerization (ATRP) of methyl acrylate (MA), n‐butyl acrylate (BA), or methyl methacrylate (MMA). The ATRP of MA and BA proceeded in a controlled fashion using either a Cu(I)Cl/PMDETA or Cu(I)Cl/Me6TREN catalyst system, as evidenced by a linear increase in molecular weight with conversion and low PDIs. The polymerization of MMA was less controlled. 1H‐NMR spectroscopy was used to elucidate pentablock copolymer structure and composition. The thermal stabilities of the pentablock copolymers were slightly less than the PS‐PIB‐PS macroinitiators due to the presence of polyacrylate or polymethacrylate outer block segments. DSC analysis of the pentablock copolymers showed a plurality of glass transition temperatures, indicating a phase separated material. 相似文献
Micron-sized mono-dispersed polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) composite particles (PS/PBMA=2/1 by weight) having a heterogeneous structure in which many fine
PBMA domains dispersed in a PS matrix near the particle surface were produced by seeded polymerization of n-butyl methacrylate (BMA) of which almost all had been absorbed by 1.8 μm-sized monodispersed PS seed particles utilizing
the dynamic swelling method. The morphology was varied by changing the PS/BMA ratio and polymerization temperature. It was
concluded that the swelling state of 2 μm-sized BMA-swollen PS particles in the seeded polymerization process is one of the
important factors to control the morphology of the composite particles.
Received: 27 November 1996 Accepted: 21 March 1997 相似文献
Recently, we found that “golf-ball-like” polystyrene (PS)/poly(butyl acrytlate) composite particles could be produced by
seeded emulsion polymerization of butyl acrylate with PS seed particles. In this article, the theoretical and experimental
thermodynamic instabilities of the golf-ball-like structure are discussed and are compared with core-shell and hemispherical
morphologies.
Received: 2 February 1999 Accepted in revised form: 3 June 1999 相似文献
The emulsion polymerization process allows production of polymer particles with different structural morphologies. Films obtained after coalescence keep some memory of this morphology, but large modifications can occur during coalescence. In the present case, one of the polymers, polystyrene (PS), exhibits a glass temperature (Tg) much higher than the filmification temperature (close to room temperature), while the other one, poly(butyl acrylate) (PBA), has a much lowerTg. Furthermore, it is well known that dynamic mechanical measurements can be very helpful in providing information on the morphology of polymer materials, i.e., on geometrical and topological arrangement of homopolymer domains. At first, this method was used for comparison of two types of films: i) the first one obtained from structured-core (PS)-shell (PBA) particles, ii) the second one obtained from a blend of homopolymer particles (PS and PBA). It appears that the expected core-shell particles lost their geometric structure in the second film. Second, comparison of the predicted dynamic modulus and experimental data shows that i) strong interactions exist between PS nodules unless their coalescence has occured, leading to an abnormally high modulus at room temperature, ii) after achieving their coalescence, PS forms a more or less continuous phase. Both phenomena strongly depend on the particle size and their respective volume fractions. 相似文献
Micron-sized monodispersed polymethyl methacrylate (PMMA)/polystyrene (PS) (PMMA/PS=2/1, wt ratio) composite particles consisting
of PMMA-core and PS-shell were successfully produced by seeded dispersion polymerization of styrene in a methanol/water medium
in the presence of about 2 μm-sized monodispersed PMMA particles. From the view point of thermodynamic equilibrium, such a
morphology is difficult to form by usual seeded polymerization in a polar medium such as water. It is concluded that seeded
dispersion polymerization in which almost all monomers and initiators exist in the medium has an advantage to produce core/shell
polymer particles in which polymer layers accumulate in their order of the production regardless of the hydrophobicity of
polymers, because of high viscosity in polymerizing particles.
Received: 9 December 1996 Accepted: 26 February 1997 相似文献
Recently, the authors reported that micron-sized monodispersed cross-linked polymer particles having a single hollow in the
inside were produced by seeded polymerization for the dispersion of (toluene/divinylbenzene)-swollen polystyrene (PS) particles
prepared utilizing the dynamic swelling method which the authors had proposed. In this article, the particles at various conversions
of the seeded polymerization were observed with an optical microscope in detail. From the obtained results, the formation
mechanism of the hollow structure is suggested as follows. As seeded polymerization proceeds, poly-divinylbenzene (PDVB) molecules
precipitated in the swollen particle are trapped near the interface and gradually pile at the inner surface, which results
in a cross-linked PDVB shell. PS which dissolves in the swollen particles is repelled gradually to the inside. After the completion
of the polymerization, toluene in the hollow evaporates by drying, and PS clings to the inner wall of the shell uniformly.
Received: 14 February 1997 Accepted: 16 April 1997 相似文献
Polymer particles having single hollow in the inside were successfully prepared by suspension polymerization for divinylbenzene/
toluene droplets dissolving polystyrene (PS) in an aqueous solution of poly(vinyl alcohol). Such a hollow polymer particle
was not obtained without PS. The hollow structure was affected by the molecular weight and the concentration of PS.
Received: 3 December 1997 Accepted: 27 March 1998 相似文献
By introducing an hydroxyl group and a lipophilic branch into the middle of lipophilic head of emulsifier 12-oxy-9-octadecenoic
acid, a new emulsifier was synthesized and applied in microemulsion polymerization. When the emulsifier content in the microemulsion
was kept to about 12%, the highest monomer content in microemulsion could achieve 35% for BA, 20% for St and MMA. The microemulsion
with high monomer content remained clear after polymerization, and the average diameters of polymer particles were 38.9 nm
for St microemulsion, 47.4 nm for BA, and 50.7 nm for MMA.
Received: 18 November 1997 Accepted: 16 January 1998 相似文献
New flame-retardant nano/micro particles of sizes ranging between 0.06 ± 0.01 and 1.70 ± 0.23 μm were formed by dispersion polymerization of the pentabromobenzyl acrylate monomer (PBBA) in methyl ethyl ketone as a continuous phase. The effect of various polymerization parameters, e.g., monomer concentration, initiator type and concentration, stabilizer concentration and crosslinker monomer concentration, on the size, size distribution and polymerization yield of the produced poly(pentabromobenzyl acrylate) particles has been elucidated. Poly(pentabromobenzyl acrylate)/polystyrene (PPBBA/PS) nano/micro blends of the contents of different PPBBA particles were prepared by mixing the PPBBA particles with a PS solution in methylene chloride, followed by evaporation of the methylene chloride from the mixture. The thermal stability of these blends was also studied. 相似文献