Chia-Fen Lee

Synthesis and properties of polymer latex with carboxylic acid functional groups for immunological studies

Abstract The poly(methyl methacrylate) (PMMA)/poly(methyl methacrylate)–poly(methyl acrylate acid) copolymer (PMMA–PMAA) composite polymer latex were synthesized by the method of soapless seeded emulsion polymerization. The morphology of the composite polymer latex was core–shell structure. The core was PMMA and shell was PMMA–PMAA copolymer. Because the PMMA–PMAA copolymer was shell, the carboxylic acid functional groups (COOH) of MAA distributed on the surface of composite polymer latex. The concentration of carboxylic acid groups distributed on the surface of composite polymer latex could be controlled by the amount of MAA. Antigens (Bovine Serum Albumin (BSA) or Anti-human IgG) were chemically bound onto the surface of PMMA/PMMA-PMAA core–shell composite latex by the method of either pre-activation or pre-adsorption to form the protein-coated latex (immunolatices). The more the carboxylic acid groups on the latex, the more the antigens were bound onto the surface of PMMA/PMMA–PMAA core–shell composite latex. The immunolatices had the higher stability than the parent composite latex due to the effect of steric hindrance of the antigens. Moreover, the sensitivity of the immunological agglutination of immunolatices was significantly influenced by the amount of covalently bound antigens and temperature.

The Tapestry Cellular Automata phase unwrapping algorithm for interferogram analysis

A newly developed phase-unwrapping algorithm, which is termed Tapestry Cellular Automata, are presented. Fundamental restrictions of traditional path-dependent phase unwrapping algorithms such as noise propagation and inconsistent data reconstruction are discussed first. The advantages and drawbacks of a path-independent algorithm, Cellular Automata, are then examined. The parallel and distributed processing nature of Tapestry Cellular Automata is shown to be able to keep the merits of traditional Cellular Automata algorithm while taking advantage of the rapid advancement of personal computers such as distributed computing over internet or intranet and multi-tasks operating environment. Both numerical simulation and experiments used to examine the effectiveness of this newly developed algorithm are presented in detail as well.

Kinetic study on the poly(methyl methacrylate) seeded soapless emulsion polymerization of styrene. III. Seeds with crosslinking

In this work, a seeded soapless emulsion polymerization was carried out with crosslinking (XL) poly(methyl methacrylate)(PMMA) as seeds, styrene as monomer, and potassium persulfate (K 2 S 2 O 8 ) as initiator to synthesize the PMMA XL-PS composite latex, which we knew as the latex interpenetrating polymer network (IPN). The morphology of the latex IPN was observed by transmission electron microscopy (TEM). It showed a core-shell structure. The kinetic data from the early stages of the reaction of seeded soapless emulsion polymerization showed that the square root of polymer yield (Wp) 1/2 was proportional to the reaction time. The reaction rate decreased with the increase of crosslinking density of PMMA seeds. The core-shell model proposed in our previous work 1-2 was modified to predict the conversion of polymerization over the entire course of the synthesis of PMMA (XL)-PS composite latex. Our modified core-shell kinetic model fitted well with the experimental data.

Soapless emulsion polymerization of methyl methacrylate. II. Simulation of polymer particle formation

In this work, a generalized mathematical model was developed to estimate the variation of particle concentration during the entire course of soapless emulsion polymerization of methylmethacrylate (MMA). All of the factors, such as oligomeric radical absorption or desorption by polymer particles, coagulation between polymer particles, and the termination effect on the formation mechanism of polymer particles, were considered and included in this model. When appropriate parameters were selected, this model could be successfully used to interpret the experimental behavior of particle concentration during the entire reaction. Under different conditions, the rate of polymerization, the number of radicals in each particle, the instantaneous average molecular weight of polymers, and the rate constant of termination were also calculated. All of them coincided with the experimental results quite well.

Morphology, thermal property, and mechanical property of core-shell latex polymers. I. Effect of heating and pressuring on PBA/PS linear composite polymer

In this work, butyl acrylate and styrene were used as monomers in the first stage and second stage of polymerization, respectively, and potassium persulfate (K2S2O8) was used as the initiator to synthesize the poly(butyl acrylate)–polystyrene (PBA/PS) composite latex by the method of two-stage soapless emulsion polymerization. The morphology of the latex particles was observed by transmission electron microscopy (TEM), which showed that the composite latex particles had a core–shell structure. The particle-size distribution of the composite latex was very uniform. A thin layer of a PBA-graft-PS copolymer was formed in between the core (PBA) and shell (PS) regions, which thus increased the compatibility between the PBA and PS phases. The process of heating and pressuring influenced the morphology, mechanical properties, and thermal properties of the PBA/PS composite polymer.

Study on the synthesis of poly(methyl methacrylate)–poly(methacrylic acid) composite latex and their humidity sensitive properties

The composite latex particles of poly(methyl methacrylate)–poly(methacrylic acid) [poly(MMA–MAA)] were synthesized through either soapless seeded emulsion polymerization or a soapless emulsion copolymerization technique. The reaction kinetics, morphology, and size of latex particles, composition, glass transition temperature (Tg), and molecular weight of polymer products were studied under different experimental conditions. Moreover, this work also focused on the humidity-sensitive properties of the polymer films fabricated by melting under the temperature of 200°C and followed by chemical modification with aqueous solution of NaOH. It is confirmed that there exists both an optimum ratio of hydrophilic to hydrophobic monomers and the initial structure of the latex particle to provide the humidity-sensitive polyelectrolyte film with excellent water resistivity and good sensitivity to humidity. Besides, little hysteresis and quick response were observed.

Synthesis of monodispersed polystyrene–silver core–shell particles and their application in the fabrication of stretchable large-scale anisotropic conductive films

Monodispersed core–shell conductive particles are designed and produced as efficient electron transporting materials for anisotropic conductive films. Traditionally, particle size control was required usually owing to the demand of anisotropic conductive films. Here, an innovative and facile method is proposed to prepare large-scale anisotropic conductive films by incorporating organic–inorganic core–shell conductive particles. First of all, monodispersed polystyrene–silver (PS–Ag) core–shell particles were prepared by emulsifier-free emulsion polymerization and a modified electroless plating process. A series of variables were used to synthesize the PS–Ag conductive particles to enhance the mobility of electrons in a given medium. The resulting PS–Ag conductive particles had excellent bulk conductivity with Ag nanoshells compactly embedded on the surface of PS colloids. In addition, the PS–Ag conductive particles were further mixed with soft latex particles of poly(styrene-co-butyl acrylate), P(St–BA), and then followed by the film-forming process. After the formation of large-scale anisotropic conductive films by the gravity sedimentation method, a remarkable flexible behavior with good conductivity was obtained. The presented method shows the significance of developments in electronic fields and is expected to be a practical, facile, and general approach for the fabrication of anisotropic conductive films with good flexibility and stretchability.

Self-assembly behaviors of thermal- and pH- sensitive magnetic nanocarriers for stimuli-triggered release

In the present work, we prepare thermo- and pH-sensitive polymer-based nanoparticles incorporating with magnetic iron oxide as the remote-controlled, stimuli-response nanocarriers. Well-defined, dual functional tri-block copolymer poly[(acrylic acid)-block-(N-isopropylacrylamide)-block-(acrylic acid)], was synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization with S,S′-bis(α,α′-dimethyl-α″-acetic acid)trithiocarbonate (CMP) as a chain transfer agent (CTA). With the aid of using 3-aminopropyltriethoxysilane, the surface-modified iron oxides, Fe3O4-NH2, was then attached on the surface of self-assembled tri-block copolymer micelles via 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinamide (EDC/NHS) crosslinking method in order to furnish not only the magnetic resources for remote control but also the structure maintenance for spherical morphology of our nanocarriers. The nanocarrier was characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet–visible (UV/Vis) spectral analysis. Rhodamine 6G (R6G), as the modeling drugs, was encapsulated into the magnetic nanocarriers by a simple swelling method for fluorescence-labeling and controlled release monitoring. Biocompatibility of the nanocarriers was studied via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, which revealed that neither the pristine nanocarrier nor the R6G-loaded nanocarriers were cytotoxic to the normal fibroblast cells (L-929 cells). The in vitro stimuli-triggered release measurement showed that the intelligent nanocarriers were highly sensitive to the change of pH value and temperature rising by the high-frequency magnetic field (HFMF) treatment, which provided the significant potential to apply this technology to biomedical therapy by stimuli-responsive controlled release.

The effect of aqueous medium contains poly(acrylic acid) on the morphology of composite polymer particle produced by two stages soapless seeded emulsion polymerization

Abstract The linear composite polymer particles, which contain PMMA and PS components (PMMA/PS composite particle), were synthesized by the method of two stages soapless seeded emulsion polymerization. In this study, the aqueous medium of the emulsion system included poly(acrylic acid) (PAA). In the second stage reaction, the morphology of the PMMA/PS composite particles was changeable under the influence of PAA. In the initial period of second stage reaction, the morphology of the composite particle showed the core(PMMA)–shell(PS) structure, in the middle period of second stage reaction, thermodynamic was the main factor to decide the morphology of the core and two shells, that is, PS as core, PMMA mixed with PS as inner shell, and PS as outer shell. Finally, the PMMA/PS composite particle showed the morphology of core(PS)–shell(PS phase dispersed in PMMA phase). This was in great contrast to the morphology of PMMA/PS composite particles, which were synthesized in the absence of PAA.

Polymer latex containing carboxylic acid functional groups. I. Synthesis of polymer latex from MMA and AA

The polymer latex of poly(MMA-AA) was synthesized using two techniques: soapless seeded emulsion polymerization, and the soapless emulsion copolymerization technique. The reaction kinetics, morphology, composition, and size of latex particles, as well as the structure using thin-layer chromatographic separation techniques, glass transition temperature (T g ), and molecular weight of polymer products, were studied under different experimental conditions. The reaction of the hydrophilic AA monomer took place in two places-on or in the latex particles, and in the water phase. Therefore, the polymer latex, whose size is very small and uniform, dispersed uniformly all over the PAA continuous phase.