In situ photocrosslinkable hyaluronic acid‐based surgical glue with tunable mechanical properties and high adhesive strength

Hyaluronic acid (HA), a naturally occurring linear polysaccharide, has been widely used as a key biomaterial in a range of cosmetic and therapeutic applications. Its excellent biocompatibility and bio‐functions related to tissue regeneration encourage the development of HA‐based hydrogels to expand its applications. This study details an in situ forming surgical glue based on photocrosslinkable HA, providing tunable mechanical properties and firm tissue adhesion under wet and dynamic conditions. Depending on the degree of photocrosslinkable methacrylate groups in HA polymer chains, the mechanical properties of hyaluronate methacrylate (HAMA) hydrogels prepared by UV photocrosslinking was improved. Ex vivo adhesion tests revealed that HAMA hydrogels exhibited 3‐fold higher shear adhesive strength compared to gelatin methacryloyl hydrogels and achieved firm adherence to the porcine skin tissue for several weeks. The high adhesive strength of HAMA hydrogels, under dry and wet conditions, suggests that it may have great promise as a tissue adhesive. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 522–530     

聚丁二烯丙烯酸酯液态光学透明胶的合成及其UV固化膜的性能

针对丙烯酸酯大单体在合成过程中常带有颜色,以及由其制备的液态光学透明胶的UV固化膜易黄变的问题,本文报道了一条新的大单体合成路线:首先以端羟基聚丁二烯(HTPB)、萘钾、丙烯酰氯(AC)为原料,通过一锅法合成了一种无色透明的聚丁二烯丙烯酸酯大单体(PBAM);然后将PBAM与丙烯酸酯活性稀释单体、光引发剂混合,制备了液态光学透明胶;最后通过UV固化制备了一系列无色透明的薄膜。利用GPC、1H-NMR、FTIR等手段对PBAM进行了表征;进一步研究了液态光学透明胶UV固化膜的光学性能、耐黄变性能、耐低温性能等。结果表明:基于新路线合成的PBAM呈现无色透明,液态光学透明胶的UV固化膜展现出优良的光学性能和耐黄变性能,固化膜透光率高达98%;经紫外线加速老化264h后,色差(ΔE)≤1.5;此外,该固化膜还具有优良的耐低温性能,玻璃化转变温度为-30℃。     

Recent progress in polymer hydrogel bioadhesives

Adhesive hydrogels have broad applications in tissue adhesives, hemostatic agents, and biomedical sensors. Various bio-inspired glues and synthetic adhesives are clinically used as conventional hemostatic agents and auxiliary tools for wound closure. Medical adhesives are needed to effectively and quickly control bleeding, thereby reducing the risk of complications caused by severe blood loss. Medical sensors need to have excellent skin compliance, mechanical properties, sensitivity, and biological safety. This review focuses on recent progress in adhesive hydrogel systems, their structures, adhesion mechanisms, construction strategies, and emerging applications in the biomedical field.     

In Vitro and In Vivo Characterization of Biodegradable Reactive Isocyanate‐Terminated Three‐Armed‐ and Hyperbranched Block Copolymeric Tissue Adhesives

Tissue adhesives are an attractive class of biomaterials, which can serve as a treatment for meniscus tears. In this study, physicochemical and adhesive properties of novel biodegradable three‐armed‐ and hyperbranched block copolymeric adhesives are evaluated. Additionally, their degradation in vitro and in vivo, and the tissue reaction after subcutaneous injection in rats are assessed. The developed adhesives have sufficient adhesive strength to meniscus tissue after curing (66–88 kPa). Networks based on the three‐armed adhesive have tensile properties that are in the same range as human meniscus. After 26 weeks, networks based on the hyperbranched adhesive show a faster mass loss (25.4%) compared to networks prepared from the three‐armed ones (5.5%). Both adhesives induce an inflammatory reaction, however, no necrosis and only initial toxic effects on peripheral tissues are observed. The proposed materials are suitable candidates for the use as resorbable tissue adhesives for meniscus repair.     

Autooxidized Polyunsaturated Oils/Oily Acids: Post-it Applications and Reactions with Fe(III) and Adhesion Properties

Soybean oil, sesame oil, linoleic acid and linolenic acid were epoxidized, peroxidized and hydroperoxidized via autooxidation under air oxygen and sunlight at room temperature to obtain novel post-it materials. Polymeric soybean oil peroxide and sesame oil peroxide were containing soluble part of 60%(w/w) together with crosslinked part of 40%(w/w) while polymeric linoleic and polymeric linolenic acids were completely soluble. The autooxidized soluble products with Mn varying between 800 and 3100 Daltons were used as post-it adhesive. The highest adhesion was observed in the case of polymeric soybean oil (3.0 Newton), while adhesion of commercial epoxidized soybean oil, polymeric linoleic and polymeric linolenic acid were 0.8, 0.5 and 0.5 Newton, respectively. Reactions of the autooxidized soluble products with Fe(NO₃)₃. 4H₂O in the presence of ethanol, glycerol and diethyleneglycol gave the hydroxy functionalized products with the same M_n values and indicating no adhesive properties. When the commercial epoxidized soybean oil was reacted with Fe(NO₃)₃. 4H₂O in the presence of the alcohols, Mn of the hydroxy functionalized polymeric oil was found to be unchanged. ¹H NMR, FT-IR, SEM and GPC techniques were used in the characterization of the products obtained.     

复合材料层合板单搭胶接力学性能检测技术与分析

胶接工艺缺陷对单搭胶接接头的拉伸剪切性能有着重要的影响。为了研究不同单搭接胶接层厚度对不同材质复合材料层合板胶接性能的影响规律,通过喷水穿透法超声C扫描对试样的剪切区域进行无损检测,并分别采用1mm、2mm、4mm的胶层厚度,以碳纤维/玻璃纤维复合材料层合板为被粘物,进行单搭胶接拉伸剪切性能试验。检测及试验结果表明:当胶层厚度h1mm时,对于相同材料的被粘物,胶层厚度越大,试件胶接接头剪切强度越小;相同的粘接剂厚度,以碳纤维增强复合材料板为被粘物的试件胶接接头剪切强度大于以玻纤增强复合材料板为被粘物的试件胶接接头强度;胶粘剂与碳纤维被粘物表面的润湿效果要优于胶粘剂与玻纤被粘物表面的润湿效果。     

内聚力模型的形状对胶接结构断裂过程的影响

内聚力模型被广泛应用于粘接结构的断裂数值模拟过程中,为深入分析不同形状内聚力模型与胶黏剂性质和粘接结构断裂之间的关系,本文分别采用脆性和延展性两种类型胶黏剂,对其粘接的对接试件进行了单轴拉伸、剪切实验,以及其粘接的双臂梁试件进行了断裂实验.3种类型的内聚力模型(抛物线型、双线型和三线型)分别模拟了以上粘接结构的断裂过程,并与实验结果进行对比.结果发现:双线型的内聚力模型适用计算脆性胶黏剂的拉伸与剪切的断裂过程;指数型内聚力模型较适合计算延展性胶黏剂的拉伸和剪切的断裂过程,临界应力、断裂能和模型的形状参数是分析拉伸和剪切的重要参数;双臂梁试件的断裂过程模拟结果发现,断裂曲线与胶黏剂性质有关,内聚力模型形状参数也有影响.通过实验与计算结果分析,双线型内聚力模型更适合脆性胶黏剂粘接的双臂梁断裂计算,而三线型更适合计算延展性胶黏剂粘接的双臂梁断裂过程,此研究结果对胶黏剂的使用和粘接结构的断裂分析有很重要意义.     

纳米碳基材料在导电胶黏剂中的应用

具有导电、导热等功能的胶黏剂相对于普通胶黏剂具有更高的应用价值,在电子封装领域已得到了广泛应用,然而其成本受制于高体积含量的贵金属填料而无法有效降低。本文基于这些现状总结和分析了近些年来国内外对于解决这类问题的方法和最新研究成果,发现碳纳米管、石墨烯等纳米碳材料具有优异的力学、导电和导热能力,与金属填料复合可以降低10wt%~20 wt%的金属填料含量。特别地,碳纳米管作为一维纳米材料能够作为“桥梁”将导电金属填料相互连接起来,可有效提高胶黏剂的导电能力、热稳定性和力学性能,同时降低填料的导电导热阈值和制备成本。通过聚合物基体(如热塑性与热固性树脂)的优化与选择,胶黏剂的力学性能可得到进一步的改善,以便满足于柔性电子器件的封装要求。另外,我们认为通过化学方法制备纳米粒子高温固化后也可以烧结构筑导电导热网络,提高材料的性能。     

层层组装构筑聚电解质/碳纳米管导电黏附膜

首先将聚烯丙基胺盐酸盐与碳纳米管制成复合物(PAH-CNT), 再通过层层组装技术构筑了聚丙烯酸和碳纳米管混合物(PAA-CNT)与PAH-CNT多层复合膜(PAH-CNT/PAA-CNT). PAH-CNT/PAA-CNT多层复合膜同时具有导电和黏附性能. 在玻璃和ITO基片上沉积的PAH-CNT/PAA-CNT多层复合膜的最大拉伸剪切强度接近7 MPa, 即1 cm²的黏附膜可以承受约70 kg的重物. 碳纳米管的引入使PAH-CNT/PAA-CNT多层复合膜具有更好的导电性.     

Effect of adhesive thickness,adhesive type and scarf angle on the mechanical properties of scarf adhesive joints

The effects of adhesive thickness, adhesive type and scarf angle, which are determined as the main control parameters by the dimensional analysis, on the mechanical properties of a scarf adhesive joint (SJ) subjected to uniaxial tensile loading are examined using a mixed-mode cohesive zone model (CZM) with a bilinear shape to govern the interface separation. Particularly, the adhesive-dependence of the vital cohesive parameters of CZM, which mainly include initial stiffness, total fracture energy and separation strength, is introduced emphatically. The numerical results demonstrate that the ultimate tensile loading increases as the adhesive thickness decreases. Cross the ultimate tension, the joint loses the load-bearing capacity when adopting the brittle adhesive but sustains partial load-bearing capacity while selecting the ductile adhesive. In addition, for the joint with the ductile adhesive, the maximum applied displacement until the complete failure of it is directly proportional to the adhesive thickness, which is different from the case using the brittle adhesive. Taking the combination of the ultimate loading and applied displacement into account, failure energy is employed to evaluate the joint performances. The results show that the failure energy of the joint with the brittle adhesive increases as the adhesive thickness decreases. Conversely, the situation of the joint using the ductile adhesive is vice versa. Moreover, the effect of the adhesive thickness becomes more noticeable with decreasing the scarf angle owing to the variation of the proportion of each component of the mixed-mode. Furthermore, all the characteristic parameters (the ultimate tensile loading, the maximum applied displacement and the failure energy) that adopted to describe the performances of SJ increase as the scarf angle decreases. Finally, the numerical method employed in this study is validated by comparing with existing experimental results.