梯度渗透法组装仿木年轮结构壳聚糖棒材

受树木生长过程的启示，建立了一种新型的壳聚糖成型方法，以氢氧化钠梯度溶液通过膜渗透中和壳聚糖醋酸溶液，使壳聚糖原位沉析，自行组装成仿木年轮结构材料.以体积分数为2％的乙酸溶液为溶剂，配制质量分数为4％的壳聚糖溶液，然后将其注满模具，脱模后依次放入质量分数为3%、4%、5%的NaOH凝固液中凝固1 h，制备了具有仿树木年轮结构的壳聚糖棒材.通过改变凝固液中NaOH的质量分数可以调节材料中层状结构的层厚与层间距.力学性能测试表明该材料的抗弯强度高达96.8 MPa.采用梯度渗透法制备的壳聚糖棒材不仅在形态上与树木的年轮相似，而且仿木年轮结构起到了提高材料力学性能的作用，使其更适合作为骨折内固定材料.

Chitosan rods with annual ring structure prepared via grade-pervasion precipitation

Illuminated by the wood growing process,a novel grade-pervasion precipitation method was proposed to prepare chitosan rods with annual ring structure.NaOH aqueous solutions with different concentration were used to neutralize chitosan solution through membrane to get chitosan rods with layer-by-layer structure similar to the wood annual ring.Two percent HAc aqueous solution was used to dissolve chitosan powder to get 4% chitosan solution.And then put the chitosan solution into 3%,4%,5% NaOH(aqueous) solutions for 1 h one after another.Result indicated that the obtained chitosan rod had high bending strength(96.8 MPa).Changing the concentration of NaOH aqueous solution could control the layer number and the thickness of each layer.Annual ring structure enhances the rod's bending strength,so it can be used to prepare chitosan nail for bone fracture.