Paramylon is a natural hydrophilic polysaccharide produced in the pyrenoids of euglenoids, and esterification may render paramylon hydrophobic. Esterification imparts not only thermoplasticity, but also potential compatibilities with other polymer resins and fillers. However, the dependence of the compatibility on the structure of the polymer ester has not yet been systematically studied. To estimate the affinities between paramylon esters and hydrophobic organic solvents/resins, the dependences of their Hansen solubility parameters, which are association indices, on the degrees of substitution and chain lengths of the ester groups were investigated. Experimental and theoretical investigations were conducted using the dissolution and Fedors methods, respectively. Esterification decreased the solubility parameter from 49 (paramylon) to approximately 18 MPa^1/2 (paramylon esters), indicating that the potential affinities of paramylon esters for hydrophobic organic solvents/polymers increased. A multiple regression analysis was also performed to investigate the effects of acyl chain length and degree of substitution with acyl groups on the solubility parameter. The solubility parameters of the paramylon derivatives were continuously variable from hydrophilic to -phobic. Hence, esterification with various acyl groups may control the hydrophobicities of paramylon esters, enhancing their miscibilities with various hydrophobic organic solvents and resins.

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基于酰基的取代度和链长对裸藻淀粉酯的汉森溶解度参数进行实验和理论估计

裸藻淀粉是在眼虫类核蛋白核中产生的天然亲水性多糖，酯化作用可使裸藻淀粉具有疏水性。酯化不仅赋予热塑性，而且还赋予与其他聚合物树脂和填料的潜在相容性。然而，相容性对聚合物酯结构的依赖性尚未得到系统研究。为了估计裸藻淀粉酯和疏水性有机溶剂/树脂之间的亲和力，研究了它们的汉森溶解度参数（缔合指数）对酯基的取代度和链长的依赖性。分别使用溶解法和 Fedors 方法进行实验和理论研究。酯化将溶解度参数从 49（裸藻淀粉）降低至约 18 MPa ^1/2（裸藻淀粉酯），表明裸藻淀粉酯对疏水性有机溶剂/聚合物的潜在亲和力增加。还进行了多元回归分析，以研究酰基链长度和酰基取代度对溶解度参数的影响。裸藻淀粉衍生物的溶解度参数从亲水性到疏水性连续变化。因此，与各种酰基的酯化可以控制裸藻淀粉酯的疏水性，增强其与各种疏水性有机溶剂和树脂的混溶性。