• Polymer(Korea)
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• v.28 no.6
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• pp.524-530
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• 2004

Polystyrene particles (PS) with poly(ethylene glycol) units on surface were formed by an emulsifier-free emulsion polymerization using styrene, poly(ethylene glycol) methacrylate (PEG-MMA) or poly(ethylene glycol) dimethacrylate (PEG-diMMA) at pH 7, and followed by freeze-drying to give the corresponding powders. The structures of PS particles were confirmed by FT-IR spectroscopy, and the particle size and distribution the PS particle were observed by scanning electron microscopy and particle analyzer. Monodisperse polymer particles were obtained at a concentration of PEG-MMA 2∼5 mol% or PEG-diMMA 1 mol% relative to styrene. The highest zeta potential of polymer surface was measured to be 183 mV at a polymer of PEG-MMA 5 mol%, which was measured in dielectric medium by means of ELS-8000 dynamic light scattering.

• Macromolecular Research
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• v.11 no.6
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• pp.425-430
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• 2003

Two types of poly(n-butyl acrylate) copolymer/silicate nanocomposites have been produced: poly(n-butyl acrylate-co-methyl methacrylate) [P(BA-co-MMA)]/silicate nanocomposites and poly(n-butyl acrylate-co-styrene) [P(BA-co-ST)]/silicate nanocomposites. The P(BA-co-MMA)/silicate nanocomposites shows the exfoliated structures but a P(BA-co-ST)/silicate nanocomposites have intercalated structures, because the BA/MMA comonomer has a higher polarity (e-value in Q-e scheme) than the BA/ST comonomer. The BA/MMA comonomer expanded the interlayer space of the silicate wider than did the BA/ST comonomer. The thermal degradation onset point of the P(BA-co-MMA)/silicate nanocomposites was 43$^{\circ}C$ higher than that of pure P(BA-co-MMA). P(BA-co-MMA)T5%, P(BA-co-MMA)T10%, and P(BA-co-MMA)T20% exhibit 134,302, and 195% increases, respectively, in their storage moduli at -20$^{\circ}C$ relative to the pure copolymer.

• Macromolecular Research
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• v.15 no.4
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• pp.302-307
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• 2007

The living radical polymerization of methyl methacrylate (MMA) by atom transfer radical polymerization, (ATRP) employing a $Fe(II)X_2/diphenyl-2-pyridyl$ phosphine (PyP) catalytic system (X=Cl, Br), was investigated using several initiators and solvents at various temperatures. Most of the polymerizations with the PyP ligand were well controlled, with a linear increase in the number average molecular weights ($M_n$) vs. conversion, with relatively low molecular weight distributions ($M_w/M_n=1.2-1.4$) throughout the reactions. The measured weights matched those of the predicted values. The ethyl-2-bromoisobutyrate (EBriB) initiated ATRP of MMA, with the $Fe(II)X_2/diphenyl-2-pyridyl$ phosphine catalytic system (X=Cl, Br), was better controlled in p-xylene at $80^{\circ}C$ than the other solvents used in this study.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.97.2-97
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• 2001

This work is concerned with the improvement of the productivity and the product quality in the polymerization reactors by using model-on-demand predictive control(MoDPC). This technique is applied to a continuous styrene polymerization reactor and a semibatch methyl methacrylate (MMA)/vinyl acetate(VAc) copolymerization reactor. The regress is constructed with the most influential variables the conversion and the jacket inlet temperature for the styrene polymerization reactor, and the free volume and the reactor temperature for the MMA/VAc copolymerization reactor through open loop operations. From the simulation results for setpoint tracking and disturbance rejection problems, it is demonstrated that the MoDPC shows ...

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.468-473
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• 1998

A mathematical model was developed for a continuous re-actor in which free radical polymerization of methyl methacrylate (MMA) occurred. Elementary reactions considered in this study were initiation, propagation, termination, and chain transfers to monomer and solvent. The reactor model took into account the density change of the reactor contents and the gel effect. A control system was designed for a continuous reactor using extended Kalman filter (EKF) based non-linear model predictive controller (NLMPC) to control the conversion and the weight average molecular weight of the polymer product. Control input variables were the jacket inlet temperature and the feed flow rate. For the purpose of validation of the control strategy, on-line digital control experiments were conducted with densitometer and viscometer for the measurement of the polymer properties. Despite the com-plex and nonlinear features of the polymerization reaction system, the EKF based NLMPC performed quite satisfactorily for the property control of the continuous polymerization reactor.

• Macromolecular Research
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• v.12 no.2
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• pp.233-239
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• 2004

We prepared thermally robust fully crosslinked poly(methyl methacrylate-co-divinyl benzene) ［poly(MMA-co-DVB)］microspheres successfully by precipitation polymerization in the absence of a stabilizing agent. The DVB concentration plays a pivotal role not only in the formation of the individually stable microspheres but also in the polymerization characteristics, including the particle size, the uniformity of size, the polymerization yield, and the thermal properties. The number-average diameter of the microspheres increased linearly, from 0.72 to 2.15 $\mu\textrm{m}$, and the particle size distribution became narrower, by elevating the uniformity from 1.35 to 1.12, as the DVB concentration increased from 20 to 75 mol%. In addition, the yield of the polymerization increased, from 73.4 to 98.6%, as the DVB concentration increased. Since the prepared particles possess fully crosslinked microstructures, no glass transition temperatures were observed, but all the samples prepared with DVB concentrations ranging from 20 to 75 mol% possess enhanced thermal properties. Based on the DSC and TGA data, the thermal stability of the mesospheres prepared by the precipitation polymerization is significantly improved as a result of crosslinking with DVB.

• Clean Technology
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• v.11 no.1
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• pp.41-50
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• 2005

In this study, semibatch emulsion copolymerization of n-BA as adhesive component and MMA as coagulant component were carried out for the stable acrylic polymer latex in aqueous phase for polymer cement using LE-type nonionic surfactant as environmental friendly surfactant. The stable polymer emulsion was obtained with the increases of chain length(n) of this surfactant. The effect on the amount of LE-50 as nonionic surfactant were showed that the concentration of polymer latex were increased by increasing the amount of LE-50, whereas the average particle size were decreased by increasing the amount. The addition of functional monomer in initial reactor charge showed a significant effect on the final polymer concentration and the latex particle size. The single polymerization of each n-BA or MMA showed a very low concentration of polymer latex and very big particle size due to coagulation. In the polymerization composed of mixed monomer with MMA and n-BA, the larger the ratio of MMA to n-BA in the copolymers, the greater the amount of coagulum produced. It was found that a stable copolymers were obtained in the range of 15-35 % of n-BA. Moreover, incorporation of some functional monomers in addition to of main monomers became more stable polymer latex. Through DSC and IR analysis, the final polymer latex was composed by MMA/n-BA/AA/AM with a single Tg depending on the reaction conditions. As a result, the conditions of this acrylic polymerization could also be effectively controlled to get the desired final products.

• Elastomers and Composites
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• v.46 no.1
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• pp.60-69
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• 2011

The various types of PBA/PMMA composite latexes were prepared by $2.1\;{\mu}m$ PBA seeded batch and seeded semi-continuous dispersion polymerization. The morphology of the PBA/PMMA composite latexes by seeded batch process was found to be closely dependant on the weight ratios of methanol/water in polymerization medium and of PBA seed/MMA at the second stage. In general, egg, snowman, confetti, peanut-like nonspherical composite latex particles were formed with increasing amount of water and MMA as a result of the occurrence of the phase separation between PBA seed and PMMA. The morphology of the PBA/PMMA composite latexes by seeded semi-continuous process was controlled by the addition time of MMA, especially, spherical shaped core(PBA)/shell(PMMA) composite latex particles were prepared under the monomer-starved condition at the second stage.

• Journal of the Korean Society of Clothing and Textiles
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• v.13 no.1 s.29
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• pp.89-97
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• 1989

Graft polymerization of MMA onto cotton fiber was carried out in two ways, two step graft polymerization and one step emulsion graft polymerization, using tetravalent cerium ion as an initiator. At two step graft polymerization, the first step was the pretreatment of cotton fiber with an aqueous initiator solution and the second was the grafting pretreated cotton fiber in the monomer solution. In case of one step emulsion graft polymerization, MMA was emulsified with SLS in initiator solution. Under the various graft polymerization conditions, graft yield, graft efficiency and from the Arrhenius plot the apparent activation energy were compared. The results of this study were as follows: 1. Graft yield and graft efficiency of emulsion graft polymerization were higher than those of two step graft polymerization. 2. In case of two step graft polymerization, graft yield was affected by the pretreatment time of cotton fiber with an aqueous initiator solution. And graft yield of emulsion graft polymerization was increased with the concentration of emulsifier below cmc of SLS and was decreased thereafter. 3. Elevation of temperature resulted increase in graft yield for both grafting methods. The apparent activation energy of emulsion graft pelymerzation was lower than that of two step graft polymerization. 4. Increased reaction time increased in graft yield, but decreased in graft efficiency. 5. Moisture regain of grafted cotton was decreased with graft yield.

• Journal of Integrative Natural Science
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• v.2 no.1
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• pp.1-12
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• 2009

This miniaccount presents the selective examples of our recent discoveries in the photopolymerization of vinyl monomers using the organic initiators such as hydrosilanes, poly(hydroarylsilane)s, benzoin silyl ethers, and thianthrene cation radical. In the photopolymerization of vinyl monomers with silanes polysilanes, while the polymerization yields and polymer molecular weights of the poly(MMA)s containing the silyl moieties decreased, the TGA residue yields and intensities of SiH stretching IR bands increased as the mole ratio of the silanes over MMA increased. The hydroarylsilane and poly(hydroarylsilane) seemed to influence strongly on the photopolymerizaiton of olefinic monomers as both chain initiation and chain transfer agents. For the photohomopolymerization and photocopolymerization of MA and AA, the similar trends were observed. Benzoin silyl ethers and thianthrene cation radical also exhibit the photoinitiating ability in the photopolymerization of MMA.