Enzymatic activity of trypsin adsorbed on temperature-sensitive composite polymer particles

Two kinds of temperature-sensitive composite polymer particles were prepared by seeded emulsion copolymerizations of (dimethylamino)ethyl methacrylate and ethylene glycol dimethacrylate with 0.14 μm-sized polystyrene and 0.26 μm-sized poly(methylmethacrylate) seed particles. To evaluate the usefulness as a carrier for biomolecules, the enzymatic activities of trypsin adsorbed on these two composite polymer particles were measured at temperatures above and below each lower critical solution temperature (LCST). In both cases, adsorbed trypsin retained its enzymatic activity during repeated adsorption/desorption measurements. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 883–888, 1998     

Production of micron-sized monodispersed cross-linked polymer particles having hollow structure

4 μm-sized monodispersed cross-linked polymer particles having hollow structure were produced as follows. First, 1.7 μm-sized monodispersed polystyrene (PS) seed particles produced by dispersion polymerization were dispersed in ethanol/water (7/3, w/w) solution in which divinylbenzene (DVB), benzoyl peroxide (BPO), poly(vinyl alcohol), and toluene was dissolved. The PS seed particles were swollen with DVB, toluene and BPO maintaining high monodispersity throughout the dynamic swelling process where water was slowly added continuously. And then, the seeded polymerization of the (toluene/DVB)-swollen PS particles was carried out.     

Micron-sized monodispersed polymer particles produced by seeded polymerization for the dispersion of high swelling of polymer particles with a large amount of monomer

 Micron-sized monodispersed polystyrene (PS)/poly(n-butyl methacrylate) composite particles were produced as follows. First, 1.77 μm-sized monodispersed PS seed particles produced by dispersion polymerization were dispersed in ethanol/water (1/2, w/w) medium dissolving poly(vinyl alcohol) as a stabilizer. n-Butyl methacrylate (BMA) monomer dissolving benzoyl peroxide initiator was emulsified in ethanol/water (1/2, w/w) solution of sodium dodecyl sulfate as emulsifier with ultrasonic homogenizer, and the BMA monomer emulsion was mixed with the PS seed emulsion. The PS seed particles absorbed with a large amount of BMA (about 150 times weight of the seed particles) for 2 h to about 10 μm in diameter while keeping good monodispersity and BMA droplets disappeared finally. The seeded polymerization was carried out at 70 °C after a certain amount of water was added to depress the redissolving of BMA from the swollen particles into the medium by raising from room temperature to the polymerzation temperature. Received: 21 February 1996 Accepted: 4 September 1996     

Production of micron-sized monodispersed composite polymer particles by seeded polymerization utilizing the dynamic swelling method

 In order to develop the seeded polymerization technique utilizing the dynamic swelling method (DSM) proposed by authors for the production of micron-sized mono-dispersed “composite” polymer particles consisting of two kinds of polymers, the seeded polymerization for the dispersion of ethyl methacry-late (EMA)-swollen PS particles prepared utilizing DSM was carried out. Monodispersed PS/poly(ethyl methacrylate) (PEMA) composite particles having 7 μm in diameter were produced by the addition of NaCl to lower the solubility of EMA in medium and by the addition of CuCl₂ as a water-soluble inhibitor to depress the by-production of submicron-sized PEMA particles. Received: 16 July 1996 Accepted: 10 October 1996     

Preparation of micron-sized monodispersed highly monomer- “adsorbed” polymer particles having snow-man shape by utilizing the dynamic swelling method with tightly cross- linked seed particles

Micron-sized, monodispersed highly styrene-“adsorbed” particles having snow-man shape were prepared by the dynamic swelling method (DSM) with tightly cross-linked polymer seed particles as follows. First, 3.8 μm-sized monodispersed polystyrene (PS)/ poly(divinylbenzene) (PDVB) (PS/PDVB = 1/10 wt. ratio) composite particles produced by seeded polymerization utilizing DSM were dispersed in an ethanol/water (6/4, w/w) solution dissolving styrene monomer, and poly(vinyl alcohol) as a stabilizer. Second, water was subsequently added to the dispersion with a micro-feeder at a rate of 2.88 ml/h at room temperature. The cross-linked seed particles adsorbed a large amount of styrene onto the surfaces and resulted in mono-dispersed highly styrene-“adsorbed” snow-man shape particles having about 10 μm in diameter. Received: 16 April 1998 Accepted: 9 June 1998     

Influence of the swelling state of seed polymer particles with monomer on the morphology of micron-sized monodispersed composite polymer particles produced by seeded polymerization utilizing the dynamic swelling method

 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     

Morphology of micron-sized monodispersed composite polymer particles produced by seeded polymerization for the dispersion of highly monomer-swollen polymer particles

 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     

Production of core/shell polystyrene/poly(3,5-xylidine) composite particles by chemical oxidative seeded dispersion polymerization

Micron-sized monodispersed polystyrene (PS)/poly(3,5-xylidine) (PXy) composite particles were produced by chemical oxidative seeded dispersion polymerization of 3,5-xylidine at 20 °C with 1.6-μm-sized monodispersed PS seed particles in HCl aqueous solution, the pH of which was always kept at 2.5 with a pH stat. The composite particles produced consisted of a PS core and a PXy shell. Received: 16 December 1998 Accepted in revised form: 25 March 1999     

Morphologies of micron-sized monodispersed composite polymer particles having crosslinked structures produced by seeded polymerizations

Three kinds of micron-sized monodispersed polystyrene (PS)/ poly(styrene - divinylbenzene) composite particles were produced by two kinds of seeded copolymerizations of styrene (S) and divinylbenzene (DVB) (PS seed/ (S+DVB)=2/1, wt. ratio; S/DVB=1/1, molar ratio) in the presence of about 2 μm-sized monodispersed PS particles, and their morphologies were examined. One was produced by a seeded dispersion copolymerization where almost monomers and initiators exist in an ethanol/water (12.6/4.0, w/w) medium. The others two were produced by seeded copolymerizations with the dynamic swelling method where almost monomers exist in the monomer-swollen particles using 2, 2'-azobisisobutyronitrile in monomer-swollen PS seed particles or using 4, 4'-azobis (4-cyanopentanoic acid) in an ethanol/water (7/43, w/w) medium. In the former polymerization, the produced composite particles had a high dense crosslinked shell, whereas in the latter two polymerizations, they did the comparatively homogeneous crosslinked structures.     

Preparation of macroporous functionalized polymer beads by a multistep polymerization and their application in zirconocene catalysts for ethylene polymerization

Macroporous functionalized polymer beads of poly(4‐vinylpyridine‐co‐1,4‐divinylbenzene) [P(VPy‐co‐DVB)] were prepared by a multistep polymerization, including a polystyrene (PS) shape template by emulsifier‐free emulsion polymerization, linear PS seeds by staged template suspension polymerization, and macroporous functionalized polymer beads of P(VPy‐co‐DVB) by multistep seeded polymerization. The polymer beads, having a cellular texture, were made of many small, spherical particles. The bead size was 10–50 μm, and the pore size was 0.1–1.5 μm. The polymer beads were used as supports for zirconocene catalysts in ethylene polymerization. They were very different from traditional polymer supports. The polymer beads could be exfoliated to yield many spherical particles dispersed in the resulting polyethylene particles during ethylene polymerization. The influence of the polymer beads on the catalytic behavior of the supported catalyst and morphology of the resulting polyethylene was investigated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 873–880, 2003     

Production of micron-sized monodispersed core/shell composite polymer particles by seeded dispersion polymerization

 The effect of the weight ratio of seed polymer/monomer on the morphology of the poly(methyl methacrylate) (PMMA)/polystyrene (PS) monodispersed composite particles produced by batch seeded dispersion polymerization of styrene with 1.64-μm-sized monodispersed PMMA seed particles in a methanol/water medium (4/1 w/w) was examined. In the PMMA/PS weight ratios of 3/1 and 2/1, the composite particles had a clear morphology consisting of a PMMA core and a PS shell. In the ratio of 1/1, a lot of small PS domains were observed in the PMMA core though the PS shell was still formed. By stepwise addition of styrene monomer, the formation of the small PS domain was depressed and complete core/shell morphology was formed. Absorption/release treatments of toluene into/from the PMMA/PS (1/1 w/w) composite particles resulted in a drastic morphological change from the core/shell structure to a multi- layered one. Received: 2 February 1999 Accepted in revised form: 7 April     

Understanding and preventing the formation of deformed polymer particles during synthesis by a seeded polymerization method

Uniformly sized porous polymer particles with different polarity namely poly(divinylbenzene), poly(vinyl acetate‐co‐divinylbenzene), poly(ethylene dimethacrylate), and poly (glycidyl methacrylate‐co‐ethylene dimethacrylate) were prepared in the micron‐size range by a seeded polymerization method. Parameters affecting the particle morphologies including monomer mixture content, porogen content, and polystyrene (PS) seed latexes were varied, and the morphologies of the resulting particles were investigated by scanning electron and confocal microscopy. The results obtained indicated that the particle shape depended dominantly on the molecular weight of the PS seed template. Deformed particles, including collapsed spheres and spheres with holes were obtained when high molecular weight PS seeds were used, whereas well‐defined polymer particles were produced easily by using low molecular weight seeds. The use of 1,1‐diphenylethylene as a chain terminator during seed polymerization is proposed in this work as an efficient method to lower molecular weight of PS in seed particles while keeping seed size small. This low molecular weight seed template retained its spherical geometry after swelling and polymerization with different second stage monomers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Effects of surfactants on the morphology of composite polymer particles produced by two‐stage seeded emulsion polymerization

Poly(methyl methacrylate) (PMMA)–polystyrene (PS) composite polymer particles were synthesized in the presence of a surfactant by two‐stage seeded emulsion polymerization. The first stage was the synthesis of PMMA particles by soapless emulsion polymerization; the second stage was the synthesis of the PMMA–PS composite polymer particles with the PMMA particles as seeds. In the second stage of the reaction, three kinds of surfactants—sodium laurate sulfate (SLS), polyoxyethylene (POE) sorbitan monolaurate (Tween 20), and sorbitan monolaurate (Span 20)—were used to synthesize the PMMA–PS composite particles. Both the properties and concentrations of the surfactants influenced the morphology of the composite particles significantly. Core–shell composite particles, with PS as the shell and PMMA as the core, were synthesized in the presence of a low concentration of the hydrophilic surfactant SLS. This result was the same as that in the absence of the surfactant. However, a low concentration of Tween 20 led to composite particles with a core/strawberry‐like shell morphology; the core region was a PS phase, and the strawberry‐like shell was a PS phase dispersed in a PMMA phase. With an increase in the concentration of SLS, the morphology of the composite particles changed from core (PMMA)–shell (PS) to core (PS)–shell (PMMA). Moreover, the effects of a high concentration of Tween 20 or Span 20 on the morphology of the PMMA–PS composite particles were investigated in this study. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2224–2236, 2005     

Production of micron-sized, monodisperse composite polymer particles having epoxy groups by seeded dispersion polymerization

 Micron-sized, monodisperse polystyrene (PS)/glycidyl methacrylate–divinylbenzene copolymer core/shell composite particles having epoxy groups in the shells were produced by seeded dispersion copolymerization of glycidyl methacrylate and divinylbenzene in an ethanol/water medium with 1.65-μm-sized, monodisperse PS seed particles. By chemical modifications of epoxy groups with sodium hydrogensulfite and dimethylamine, composite polymer particles having sulfonate and dimethylamino groups, respectively, in the shells were prepared. Received: 13 September 2000 Accepted: 31 January 2001     

Effect of polymer composition on the production of cationic multihollow polymer particles by the stepwise acid/alkali method

The effect of the polymer composition on the formation of multihollow structures formed within submicron-sized styrene–butyl acrylate–dimethylaminoethyl methacrylate terpolymer particles by the “acid/alkali method” proposed by the authors was examined. The cationic particles were produced by seeded emulsion terpolymerization with 2,2′-azobis(2-amidinopropane) hydrochloride initiator. The dimethylaminoethyl methacrylate content and the glass-transition temperature of the terpolymer greatly affected the formation of the multihollow structure. Received: 3 December 1998 Accepted in revised form: 4 February 1999     

Surface modification of polystyrene latex particles via atom transfer radical polymerization

The atom transfer radical polymerization (ATRP) technique using the copper halide/ N,N′,N′,N″,N″‐pentamethyldiethylenetriamine complex was applied to the graft polymerization of methyl methacrylate and methyl acrylate on the uniform polystyrene (PS) seed particles and formed novel core‐shell particles. The core was submicron crosslinked PS particles that were prepared via emulsifier‐free emulsion polymerization. The crosslinked PS particles obtained were transferred into the organic phase (tetrahydrofuran), and surface modification using the chloromethylation method was performed. Then, the modified seed PS particles were used to initiate ATRP to prepare a controlled poly(methyl methacrylate) (PMMA) and poly(methyl acrylate) (PMA) shell. The final core‐shell particles were characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, thermogravimetric analysis, and elementary analysis. The grafting polymerization was conducted successfully on the surface of modified crosslinked PS particles, and the shell thickness and weight ratio (PMMA and PMA) of the particles were calculated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 892–900, 2002; DOI 10.1002/pola.10160     

Morphology of micron-sized monodispersed poly(butyl methacrylate)/polystyrene composite particles produced by seeded dispersion polymerization

In order to develop the seeded dispersion polymerization technique for the production of micron-sized monodispersed core/shell composite polymer particles the effect of polymerization temperature on the core/shell morphology was examined. Micron-sized monodispersed composite particles were produced by seeded dispersion polymerizations of styrene with about 1.4-μm-sized monodispersed poly(n-butyl methacrylate) (Pn-BMA) and poly(i-butyl methacrylate) (Pi-BMA) particles in a methanol/water (4/1, w/w) medium in the temperature range from 20 to 90 °C. The composite particles, PBMA/polystyrene (PS) (2/1, w/w), consisting of a PBMA core and a PS shell were produced with 2,2′-azobis(4-methoxy-2,4-dimethyl valeronitrile) initiator at 30 °C for Pn-BMA seed and with 2,2′-azobis(isobutyronitrile) initiator at 60 °C for Pi-BMA seed. The polymerization temperatures were a little above the glass-transition temperatures (T _g) of both Pn-BMA (20 °C) and Pi-BMA (40 °C). On the other hand, when the seeded dispersion polymerizations were carried out at much higher temperatures than the T _g of the seed polymers, composite particles having a polymeric oil-in-oil structure were produced. Received: 14 October 1998 Accepted in revised form: 2 June 1999     

Acetal-functionalized polymer particles useful for immunoassays

The synthesis of core-shell type polystyrene monodisperse particles with surface acetal groups was carried out by a two-step emulsion polymerization process. In a first step, the core was synthesized by batch emulsion polymerization of styrene (St), and in the second step, the shell was polymerized by batch emulsion terpolymerization of styrene, methacrylic acid (MAA), and methacrylamidoacetaldehyde dimethyl acetal (MAAMA), using the seed obtained previously. With the aim of analyzing the effect of the thickness of the shell, the pH of the reaction medium and the weight ratio of the termonomers to prepare the shell, on the amount of the functionalized groups, several core-shell type latex particles were synthesized by two-step emulsion polymerization in a batch reactor. The latexes were characterized by TEM and conductimetric titration to obtain the particle size distribution and the amount of carboxyl and acetal groups on the surface, respectively. Looking for the applicability of the synthesized latexes in immunoassays, IgG a-CRP rabbit antibody was covalently bonded to the surface of the particles synthesized in neutral medium. The complex latex-protein was immunologically active against the CRP antigen. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1605–1610, 1997     

Production of micron-sized, monodispersed, multilayered composite polymer particles by multistep seeded dispersion polymerization

 Micron-sized, monodispersed, poly(methyl methacrylate) (PMMA)/polystyrene (PS)/PMMA/PS multilayered composite particles were successfully produced by three-step seeded dispersion polymerizations in methanol/water media. The first seeded dispersion polymerization was carried out with 2-μm-sized, monodispersed PMMA particles.     

Influences of the locations of monomer and initiator in the seeded polymerization systems on the morphologies of micron-sized monodispersed composite polymer particles

Three kinds of micron-sized monodispersed polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) composite particles (PS/BMA=2/1, wt. ratio) were produced by two kinds of seeded polymerizations ofn-butyl methacrylate (BMA) in the presence of about 2 m-sized monodispersed PS particles, and their morphologies were examined. One was produced by a seeded dispersion polymerization where almost monomers and initiators exist in an ethanol/water (1/1, w/w) medium. The others two were produced by seeded polymerizations utilizing the dynamic swelling method, where almost monomers exist in the PS seed particles, with 2,2-azobisisobutyronitrile initiator in the monomer-swollen particles and with 2,2-azobis [2-(2-imidazolin-2-yl)propane] initiator in an ethanol/water (1/5, w/w) medium. In the former polymerization, the produced composite particles had a core-shell structure consisting of a PS-core and a PBMA-shell, whereas in the latter two polymerizations, they had a POO (Polymeric Oil-in-Oil) structure consisting of a PS-matrix and many PBMA-domains, regardless of the location of initiator in the systems. From these results, it is concluded that the location of BMA monomer in the seeded polymerization systems with micron-sized monodispersed PS seed particles greatly affects the morphologies of produced PS/PBMA composite particles.Part CLI of the series Studies on Suspension and Emulsion