Citric acid를 기반으로 한 고흡수성 수지 합성

Abstract

고흡수성 고분자(SAP)는 친수성을 가진 고분자 사슬이 가교를 통해 망 구조를 형성하여 자기 무게 대비 1000% 이상 물을 흡수할 수 있는 고분자로 현재 주로 위생용품에서 사용되고 있으며 그 외에도 농업, 오수처리, 약물 전달 시스템 등 다양한 응용분야를 가지고 있다. 그러나 현재 SAP 합성에 주로 사용되고 있는 polyacrylic acid (PA)의 난분해성은 환경 문제를 유발하며 단량체로 사용되는 acrylic acid는 배아독성을 가지고 있어 대체가 필요하다. 이를 개선하기 위해 바이오 기반 물질인 citric acid (CA)를 사용하여 고흡수성 고분자를 합성하였다. CA는 다관능기를 가지고 있어 가교를 형성할 수 있는 친수성 단량체로 SAP을 합성하기에 적합한 구조를 가지고 있다. 이 논문에서는 1차적으로 CA와 다양한 diol을 활용하여 흡수율이 가장 높게 측정되는 1,4-butanediol을 선정하였으며 2차적으로는 이온강도의 증가를 통한 SAP의 흡수율 향상을 위해, CA를 중화하여 얻은 monosodium citrate(CN)를 도입하여 흡수율이 500% 향상시켰다. 2차 결과물의 가교 결합을 hexamethylene diisocyanate (HDI)를 사용하여 보완함으로서 구조를 안정시킬 수 있었고 흡수율을 280% 증가한 2236%가 측정되었다.|Along with the up-rise of environment problems, ecofriendly materials that can replace existing monomers has become an issue. In this paper, super absorbent polymer was synthesized using bio-based material by melt polymerization without catalyst, without facilitating conventional method or acrylic acid. Bio-based monomer, citric acid (CA), is a potential monomer for synthesizing environment-friendly SAP due to its nontoxicity, numerous crosslinking sites and hydrophilicity. As for suitable counterpart, CA was reacted with various diol with different structure according to its molar ratio. After selecting optimal diol, 1, 4-butanediol, absorbency was enhanced by neutralization of CA using sodium bicarbonate which resulted in 500% increase. To further develop synthesized SAP and compensate the absence of secondary crosslinking, hexamethylene diisocyanate (HDI) was used to stabilize 3D-network structure, which led to enhancing the absorbency by 280%. The maximum absorbency of CA based SAP was 2236%.; Along with the up-rise of environment problems, ecofriendly materials that can replace existing monomers has become an issue. In this paper, super absorbent polymer was synthesized using bio-based material by melt polymerization without catalyst, without facilitating conventional method or acrylic acid. Bio-based monomer, citric acid (CA), is a potential monomer for synthesizing environment-friendly SAP due to its nontoxicity, numerous crosslinking sites and hydrophilicity. As for suitable counterpart, CA was reacted with various diol with different structure according to its molar ratio. After selecting optimal diol, 1, 4-butanediol, absorbency was enhanced by neutralization of CA using sodium bicarbonate which resulted in 500% increase. To further develop synthesized SAP and compensate the absence of secondary crosslinking, hexamethylene diisocyanate (HDI) was used to stabilize 3D-network structure, which led to enhancing the absorbency by 280%. The maximum absorbency of CA based SAP was 2236%.