高强韧可降解复合骨胶带材料的制备及其骨折愈合期力学与结构稳定性研究

Be aimed at the arduous medical problem that is difficult to fix comminuted fracture in bone clinic, the present project proposes a new approach to fix and heal bone fracture by using curable bone adhesive tape which will be daubed on the outer surface of bone fracture after jogged tightly in a natural way. The new bone adhesive tape composite system, poly(propylene fumarate) (PPF) based crosslinking network strengthened by degradable calcium polyphosphate (CPP) fibers, is to be created by integrating advantages of high strength and high toughness for degradable CPP fiber and of low UV curing intensity, degradability and high strength for PPF based polymer. Emphases are laid on studying the influences of fiber surface modification, fiber composition parameters, polymer synthesis parameters and ultraviolet (UV) irradiation parameters on the initial mechanical properties, curing properties, theological properties and also on the material dedradation and relative stabilities in both structure and mechanical properties of this PPF-based composite material before /after bone fracture curing, clarifying the strengthening and toughening mechanisms of the PPF based polymer, probing into the variation laws in mechanical properties of bone adhesive tape, newly-formed bone tissue and composite of bone adhesive tape and newly-formed bone tissue in the fixing area of bone fracture with the implanting time, extracting the critical parameters which adjust material degradation, decrease of mechanical properties and macro-/micro-structure variations during the whole implanting stage and also revealing their adjusting mechanisms, and finally evaluating the in vivo service functions of this bone adhesive tape system. The present study is expected to provide experimental dada and theoretic bases for developing the new-generation high strengthening/toughening degradable bone adhesive tape system which keeps stable in mechanical properties and structure during the bone fracture healing but can be degraded gradually after healing.

针对骨科临床上粉碎性骨折难以固定与治疗的医学问题，提出"骨胶带外涂固定"新方法，通过融合"可降解聚磷酸钙纤维高强韧性"与PPF基聚合物"低强度UV固化性、可降解性及高强度"的优势，构建出可降解聚磷酸钙纤维增强PPF基复合骨胶带材料体系，并通过研究聚磷酸钙纤维表面改性、纤维复合、聚合物合成及UV固化等各组参数对PPF基复合骨胶带材料初始力学、固化、流变学等性能及骨折愈合期前后材料降解、力学与结构变化等的影响规律，阐明PPF基聚合物强韧化机理，并探索骨折愈合过程中骨胶带材料、新骨组织及骨折固定区"新骨组织与骨胶带材料复合体"三者力学性能随体内植入时间的变化规律，提炼出骨折愈合期前后调制材料降解、力学与结构变化等的主控参数，揭示其调控机制，综合评价复合骨胶带材料体内服役性能，为最终开发出"骨折愈合期内力学与结构相对稳定、愈后材料逐渐降解"的新一代可降解高强韧复合骨胶带提供实验数据与理论依据。

本项目结合骨科临床上粉碎性骨折难以固定与治疗的医学问题，提出“骨胶带外涂固定”新方法，通过融合“可降解羟基磷灰石纤维”与PPF/PBF基聚合物“低强度UV固化性、可降解性及高强度”的优势，成功制备出两种不同的骨胶带材料：聚富马酸丙二醇酯（PPF）基和聚富马酸丁二醇酯（PBF）基复合骨胶带材料。复合骨胶带材料的热稳定性能测试结果表明，PBF基骨胶带材料的热稳定性能强于PPF基骨胶带材料，双键比为0.5的骨胶带复合材料的热稳定性能最好，便于高温杀菌。复合骨胶带材料的力学性能显示，PBF基复合骨胶带材料的力学性能略强于PPF基复合骨胶带材料，其剪切强度为1.68±0.06 MPa~0.31±0.05 MPa，粘接强度为5.24±1.21 MPa~1.01±0.50 MPa，压缩强度为36.53±0.08 MPa~19.89±0.11 MPa。当掺杂不同比例的羟基磷灰石纤维后，力学强度均有一定程度的增加，尤其当纤维含量为3%时，其强度变化效果最为明显。体外粉碎性骨折模型的力学试验表明，双键比为0.5和2的PPF/PPF-DA复合骨胶带试样中掺杂羟基磷灰石纤维后，试样的粘接强度明显增大，但剪切强度稍有降低。在体外PBS缓冲盐溶液浸泡条件下（浸泡周期为1~52 周），我们揭示了复合骨胶带材料的失重率、溶胀度、吸水率、宏/微观结构、pH值等随浸泡时间的变化规律，以及聚合物双键比与材料降解速率之间的关联性，同时发现PPF基骨胶带材料降解速率比PBF基骨胶带材料的降解速率要快。此外，我们还通过意外发现，PPF和PBF基复合材料在LED封装胶领域具有广阔的应用前景。综上，本研究工作为最终开发出新一代可降解高强韧复合骨胶带提供了重要的实验数据与理论依据。