Mg(OH)₂/유기 나노복합체 및 생분해성 고분자의 나노입자 제조

Abstract

본 실험을 통해 초임계 이산화탄소 내에서 PMBA (poly methacryloyl β-alanine) 나노입자를 성공적으로 얻을 수 있었고, 입자의 크기를 온도 및 압력 변화 따라 조절할 수 있었다. 또한, 초임계 이산화탄소를 용매로 사용하여 환경적인 이점과 함께 고분자 입자로부터 용매를 쉽게 분리 할 수 있었다. β-알라닌(β-alanine)과 염화 메타크릴로일(methacryloyl chloride)을 이용하여 제조한 MBA를 이용하여 다양한 크기의 PMBA를 중합하였다. 개시제의 첨가량이 전환율에 상당한 영향을 주는 것이 확인 되었고, 고압에서의 온도의 변화는 전환율에는 어느정도 영향을 미치나 PMBA 입자의 크기 변화에는 큰 차이를 나타내지 않았다. 중합이 진행되는 조건의 온도에서 압력의 변화는 입자의 크기에 어느 정도 영향을 주는 것으로 나타났다. 아미노산을 포함하는 많은 고분자화합물들은 생체적합성 및 생분해성의 특성을 나타내고. 이런 고분자화합물을 나노 입자크기의 파우더 형태로 제조함으로서 보다 넓은 응용 분야를 기대할 수 있다. 이렇게 제조된 물질은 약물조성의 생기능성 물질과 약물전달 방법에 유용하게 적용될 수 있다.

Recently, there has been a lot of work on the elaboration of nanocomposite systems by embedding of inorganic particles into polymeric matrices. These materials represent a new class of polymeric materials which combine the unique physical properties of the inorganic particles with the processability and the flexibility of the organic polymer matrix. Among them, the preparation of core-shell composite particles has received particular attention due to their great potential applications. While various techniques were used to synthesize the core-shell polymer particles, a traditional method has been the emulsion polymerization with inorganic seed particles. Inorganic/organic core-shell nanocomposites were prepared by the emulsion polymerization of styrene (St) in the presence of surface-functionalized inorganic nano particles (Mg(OH)₂). Nano-sized inorganic particles were previously functionalized with a silane coupling agent, 3-(trimethoxysilyl) propyl methacrylate (γ-MPS), which was confirmed by FT-IR, and BET analysis. The average size of inorganic seed particles were around 80nm (Mg(OH)₂). The ratio of the inorganic seed particles to organic monomers, St, showed a strong influence on the stability of latex as well as the morphology of composites. Mg(OH)₂/PS core-shell nanocomposites were produced with stable latex emulsion when the weight ratio of Mg(OH)₂ to St is below 30. With the ratio increased to as high as 40, however, the latexes became less stable with aggregation and the morphology changed to irregular spherical shape. The dispersion polymerization in scCO₂ has been extensively studied since CO₂ was widely recognized as an interesting alternative to conventional organic solvent. The advantages of scCO₂ as a solvent include liquid-like density, low viscosity, high diffusivity, zero surface tension, fast mass-transfer and tunable solvent power. Moreover it is non-toxic, non-flammable, inexpensive, recyclable, and environmentally sound. It also offers advantages of easy separation of products and resolves problems related to solvent removal. In this paper, we report the preparation of amino acids based polymer in scCO₂. The PMBA (poly methacryloyl β-alanine) nanoparticles were successfully produced from the dispersion polymerization in scCO₂. This new environmentally benign process offers advantage of easy separation of composite particles from solvent.