| 학회 | 한국고분자학회 |
| 학술대회 | 2004년 가을 (10/08 ~ 10/09, 경북대학교) |
| 권호 | 29권 2호, p.451 |
| 발표분야 | 고분자 합성 |
| 제목 | Preparation of Multi Core-Shell Particles by Emulsion polymerization |
| 초록 | Core-shell latexes were synthesized by sequential emulsion polymerization of methyl methacrylate(MMA), styrene(St) and ethyl acrylate(EA) in the presence of anionic surfactant and the characteristics of these latexes were evaluated. The core latex had to be synthesized carefully to avoid the formation of secondary particles. The sequential polymerization method adopted for this synthesis took advantage of stabilizing particles grown during shell polymerization. In core-shell latex polymerization to suppress the generation of new particles and to minimize the gelation during the shell polymerization, the amount of surfactant(Sodium dodecyl benzene sulfonate : SDBS) should be reduced to the minimum, 0.01wt% and 0.02wt% of SDBS to amount of monomer, respectively, when the Polymethyl methacrylate (PMMA) and Polystyrene(PSt) core latexes are prepared. In addition, the monomer pre-emulsion method is better than monomer-add method. The core-shell structure for composite latex synthesized was demonstrated by Particle Size Analysis(PSA), Differential Scanning Calorimeter(DSC), Transmission Electron Microscope(TEM), formability of film and hydrolysis under NaOH solution. 1. INTRODUCTION Latex materials in which a core of one polymer is surrounded by a shell of a second polymer are important in many different industrial applications. For example, those with core and shell polymers differing in their glass transition temperatures(Tg) may be used to modify the properties of latex paint. The core-shell latexes with polymer phases differing in pH sensitivity have been made to manufacture void-containing particles that can be used as opaquifiers in coatings. All the earlier theoretical treatments of emulsion polymerization of styrene were based on the assumption that the particles were swollen homogeneously, i.e., there was no concentration difference throughout the particles, because styrene is miscible with polystyrene in all proportions. In this article, we describe the formulation of acrylic core-shell latex polymerization employedto build core-shell structure. The structures of these composite particles were observed by studying with respect to film formation, hydrolysis by NaOH, glass transition temperature by DSC, particle size analysis and micrological observation by TEM photograph. 2. CONCLUSION Acrylic composite particles were successfully prepared by sequential emulsion polymerization of the corresponding monomers in the presence of core latexes. When PMMA and PSt core latexes were polymerized, the appropriate amount of SDBS in the core polymerization was 1.45 × 10-5mol/L for PMMA and 2.91 × 10-5mol/Lfor PSt to suppress the generation of new particles and to minimize the the gelation during the shell polymerization in the presence of these core latexes. Moreover, a series of sequential seeded growth emulsion polymerization by adding monomers pre-emulsified were used to obtain high conversion latexes. The structure of the core-shell composite particles synthesized was confirmed by DSC, hydrolysis under NaOH, TEM, particle size analyzer and MFT study etc. All results from the above characterization show that shell polymers surrounded the core latexes and encapsulation took place during shell polymerization. |
| 저자 | 임종민, 하선희, 설수덕 |
| 소속 | 동아대 |
| 키워드 | Core-Shell; pre-emulsion; composite latex |
