Metal‐Free and Stretchable Conductive Hydrogels for High Transparent Conductive Film and Flexible Strain Sensor with High Sensitivity

Conductive hydrogels show promising applications in wearable electronic devices. However, it is still challenging to increase the conductivity as well as the mechanical performance of the conductive hydrogels. In addition, it is more challenging to fabricate ultrathin conductive films with good mechanical strength and high transparency. In this study, a metal‐free flexible conductive hydrogel for flexible wearable strain sensor with high sensitivity is presented. The conductive hydrogel is prepared by polyvinyl alcohol (PVA) templated polymerizing of polypyrrole (PPy) followed by gelating based on the polymerizing and cross‐linking of polyacrylamide (PAAm). The conductive hydrogel is endowed excellent mechanical properties by multiple hydrogen bonds between the interpenetrating network of PVA, PPy, and PAAm. The tensile strength reaches up to 0.2 MPa at 500% and the compression strength reaches up to 1.5 MPa at 90%. It can withstand cyclic loads. The conductivity reaches 0.3 s m^?1 and it is sensitive to stretching and compressing. Therefore, strain sensors are prepared based on such hydrogels to make wearable electronic devices, monitoring the subtle and large strains. It is worth noting that the composite material containing PVA has good film‐forming properties. Therefore, ultrathin conductive hydrogel films with high transparency (94.2%), high conductivity (7090 Ω/square) and large‐area are fabricated at low cost.     

Polyhydroxymethylenes as Multifunctional High Molecular Weight Sugar Alcohols Tailored for 3D Printing and Medical Applications

Common sugar alcohols used as artificial sweeteners and components of polymer networks represent low molecular weight polyhydroxymethylenes (PHMs) with the general formula [CH(OH)]_nH₂ but very low degree of polymerization (n = 2–6). Herein high molecular weight PHM (n >> 100) unparalleled in nature is tailored for 3D printing and medical applications by free radical polymerization of 1,3‐dioxol‐2‐one vinylene carbonate to produce polyvinylene carbonate (PVCA) which yields PHM by hydrolysis. Furthermore, PVCA is solution processable and enables PHM functionalization, membrane formation, and extrusion‐based 3D printing. Opposite to cellulose, amorphous PHM is plasticized by water and is readily functionalized via PVCA aminolysis/hydrolysis to produce polyhydroxymethylene urethane (PHMU), enable PHM crosslinking and coupling of PHM with amine‐functional components like gelatin. After hydrolysis/aminolysis the original PVCA shapes are retained. PVCA solution casting yields PVCA and PHM which exhibits uniform and hierarchic pore architectures. Asymmetric membranes, hydrogels, PHM/collagen blends, and electrospun nonwovens of PVCA, PHM, and PHMU are readily tailored for medical applications. 3D printing of PVCA dispersions containing hydroxyapatite affords porous PVCA, PHMU, and PHM scaffolds useful in regenerative medicine. PHM and functionalized PHMs as carbohydrate‐inspired multifunctional materials indicate in vitro biocompatibility and hold great promise for applications in medicine and health care.     

基于3D打印羟基磷灰石支架的填充结构与力学性能研究

3D打印骨组织工程支架是近来的研究热点,而制备同时具有高孔隙率和足够力学性能的骨组织工程支架是研究的难点之一。在孔隙率相同条件下,探究不同填充角度结构对3D打印支架力学性能影响。首先用SolidWorks软件设计孔隙率相同的3种不同填充角度(45°、60°、90°)支架结构,以交点处结构作为支架的最小支撑单元,并用ABAQUS软件对其进行力学性能仿真,对仿真所得单元结构压缩模量进行累加,探究填充角度对支架力学性能的影响;进而通过3D打印制备3种填充结构的羟基磷灰石支架,测试支架的孔隙率和力学性能,对仿真结果进行验证。结果表明,仿真所得3种填充结构的压缩模量比为E_s(90°)∶E_s(60°)∶E_s(45°)=12.3∶10.9∶10.0。打印得到3种不同填充角度(90°,60°,45°)的羟基磷灰石支架孔隙率无显著性差异,其压缩模量比为E_s(90°)∶E_s(60°)∶E_s(45°)=15.4∶13.1∶10.0,与仿真结果趋势一致,90°填充的支架具有最高的抗压强度((7.36±0.63) MPa)和压缩模量((33.55 ± 2.49) MPa),与力学性能最低的45°填充支架相比,抗压强提高74.8%,压缩模量提高55.18%。在孔隙率相同的条件下,单个孔型面积越小,其压缩模量和抗压强度越高。该研究为制备最优填充结构的3D打印生物支架提供分析方法和理论依据。     

3D打印成型纳米羟基磷灰石/壳聚糖/聚己内酯三元复合支架材料的构建及表征

文题释义： 组织工程骨：将体外培养的功能相关的种子细胞种植于天然的或人工合成的支架材料内,加入生长因子体外培养一段时间,将他们移植到体内,促进组织修复和骨再生的人工骨。组织工程骨形成的3要素为：支架材料、成骨细胞、生长因子。 生物陶瓷：生物表面活性陶瓷通常含有羟基,还可做成多孔性,生物组织可长入并同其表面发生牢固的键合;生物吸收性陶瓷的特点是能部分吸收或者全部吸收,在生物体内能诱发新生骨的生长。生物活性陶瓷具有骨传导性,它作为一个支架,成骨在其表面进行;还可作为多种物质的外壳或填充骨缺损。生物陶瓷有羟基磷灰石陶瓷、磷酸三钙陶瓷等。  背景：目前常用的骨缺损修复支架材料种类较多,但单一类型材料难以满足骨组织工程支架材料的要求,通过合适的方法将几种单一材料组合形成复合型材料,综合考虑各种材料优缺点,是近年来学者们的研究重点。 目的：构建纳米羟基磷灰石/壳聚糖/聚己内酯三元复合支架材料,并作表征分析研究。 方法：采用3D打印成型技术制备纳米羟基磷灰石/壳聚糖/聚己内酯多孔三元复合支架材料,从X射线衍射分析、吸水率、抗压强度、体外降解性能、孔径分析、扫描电镜分析等多个维度对支架材料进行表征研究。 结果与结论：①X射线衍射分析显示,纳米羟基磷灰石/壳聚糖/聚己内酯多孔三元复合支架的晶型峰图与羟基磷灰石粉末衍射标准卡片类似,表明该三元复合支架是通过物理作用相互结合的,不影响羟基磷灰石的生物学功能;②三元复合支架的吸水率为18.28%,亲水性好,支架可承受的最大压力为1 415 N,其体外降解速率与成骨速率相当;③显微镜下可见三元复合支架的内孔为方形,孔径250 µm,孔径大小均匀、分布有致;④扫描电镜下三元复合支架可见,壳聚糖和聚己内酯组成的纤维排列整齐有序,成网格状, 羟基磷灰石呈颗粒状在纤维表面均匀分布,三元复合材料呈现均匀、疏松的微孔结构;⑤结果表明,通过3D打印成型技术可成功制备纳米羟基磷灰石/壳聚糖/聚己内酯三元复合支架材料,其具有适度的抗压强度、一定的孔隙率、适宜的降解速度和吸水率,能为修复骨缺损的奠定基础。 ORCID: 0000-0002-6321-9160(余和东) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程       

3D打印聚醚醚酮及其复合材料修复骨缺损的应用现况

文题释义： 聚醚醚酮：是一种全芳香族半结晶性的热塑性特种工程塑料,具有优异的物理、化学、力学、热等性能。目前聚醚醚酮作为一种生物材料,相比于传统硬组织植入金属材料(不锈钢、钛及其合金等),具有良好的生物相容性、放射线透过性、植入人体后可有效降低“应力屏蔽效应”,以及磁共振扫描不产生伪影等特点,越来越多地被应用于骨科植入物和假体。 骨缺损修复：将设计制备的骨科植入物或假体植入因创伤或手术所致的骨缺损区域,经治疗后逐渐改善该区域的成骨连接状态,缓解愈合及恢复局部的功能。 背景：聚醚醚酮及其复合材料具有一系列独特的性能,而3D打印技术可以针对患者的病情定制个性化植入物,两者在骨缺损修复领域均具有明显优势。 目的：总结聚醚醚酮及其复合材料与3D 打印技术在骨缺损修复领域的应用现状,并进一步展望两者有效结合的应用前景。 方法：利用计算机检索CNKI、PubMed,Web of Science数据库,中文检索词为“聚醚醚酮,聚醚醚酮复合材料,骨缺损修复,聚醚醚酮植入物,聚醚醚酮3D打印,口腔修复”。英文检索词为“PEEK,PEEK composites,bone defect repair,PEEK implants,PEEK 3D printing,prosthodontics”。检索时限为1995年4月至2019年4月。共检索到147篇文章,根据纳入与排除标准,最终纳入51篇文献进行综述。 结果与结论：①将具有生物活性的材料及改善力学性能的颗粒或纤维引入到聚醚醚酮基体中制备成复合材料,借助3D打印技术精准定制出与患者骨缺损处高度匹配的植入物;②这种具有良好生物相容性、生物活性和力学性能的植入物在颅骨、颌骨、脊椎腰椎、人工关节以及口腔缺损修复中具有良好的治疗效果,提高了治疗后患者的满意度;③文章总结了3D打印聚醚醚酮及其复合材料在各类骨缺损修复中的应用,并对联合3D打印技术制备个性化聚醚醚酮植入物或假体的应用前景表达了自己的看法。 ORCID: 0000-0001-7850-2412(林柳兰) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

Yellow Triazine as an Efficient Photoinitiator for Polymerization and 3D Printing under LEDs

The search for new efficient photoinitiators for polymerization under the illumination of visible light is under extensive investigation due to their wide application in 3D printing. 2‐(4‐Methoxystyryl)‐4,6‐bis(trichloromethyl)‐1,3,5‐triazine (yellow triazine, R‐Cl) alone or the R‐Cl/additive systems have been indicated as promising photoinitiating systems in the free radical polymerization at 405 nm in our previous study. Here, further investigation of R‐Cl in the polymerization of a series of difunctional (meth)acrylate monomers is described. The effect of monomers on the polymerization performance is elucidated. The interplay of functional group, double bond concentration, and fluidity determines the polymerization rate and final conversions. Remarkably, R‐Cl shows better photoinitiating ability than well‐known commercial photoinitiator bisacylphosphine oxide in the polymerization of bis‐GMA/TEGDMA blend and EB605 under LED at 400 nm. The optimum concentrations of R‐Cl in the photopolymerization of TetEGDA and DPGDA monomers are revealed, the results of which are used to guide the 3D printing of DPGDA.