Microscopic defects in the amorphous regions of natural cellulose affect the mechanical properties of their materials. After dissolution and regeneration, cellulose's mechanical properties are still insufficient for application in advanced materials. Conventional compounding and crosslinking techniques with toxic crosslinking agents are not only cumbersome, but also have limited performance enhancement in cellulose materials Therefore, much attention has been paid to designing and developing more straightforward and efficient cellulose reinforcement technologies. Herein, an in situ multiscalarization strategy is used to form multiscale silk fiber-cellulose composites (MS-C) by the gradual nanosizing of silk fibers (SF) under heating in a 1-butyl-3-methylimidazolium chloride solution of cellulose (Cel-BmimCl). MS-C are constructed from micro and nano SF, fibroin chains, and cellulose molecules into a multidimensional network. Due to its advantage of multiscale structure, MS-C has excellent mechanical properties, the tensile strength and Young's modulus, which are 123.06% and 91.68% higher than that of pure regenerated cellulose after 5h heating treatment. Besides, MS-C has good biocompatibility and can be molded or 3D printed with direct ink writing, showing broad application prospects in medical, bioengineering, and other fields. This multiscale enhancement strategy can also be extended to the research and application of biopolymers such as natural polysaccharides or proteins.

Body-temperature responsive shape memory polymers (SMPs) attract a lot of attention with the application in biomedicine. Multiple SMPs regulate the response temperature through the proportion of their stationary and reversible phases by changing the molecular weight of the polymer or the components of the composite. Herein, a crosslinking reaction of trans-polyisoprene (TPI) and polycaprolactone (PCL) initiated by benzoyl peroxide gave a SMP of TPI/PCL, whose shape memory property is realized by stage-division crystallization zone. Under the fixed ratio of TPI:PCL, the crystallization performance of TPI/PCL is controlled by the crosslinking density. The response temperatures of the components in TPI/PCL are selected for the stage-division crystallization zone, making excellent shape memory performance at corresponding response temperatures. For the further achievement in controllable response temperature within a certain range, the relationship model between crosslinking density and response temperature is established, obtaining the customizable response temperature ranging 37-55 degrees C. The presented facile regulation method for response temperature will provide a new idea for the SMPs development. This study presents a triple SMP TPI/PCL by melt blending method with the initiation of BPO. The regulation of the crosslinking density can influence the crystallinity, and the relationship among Delta Hm, crosslinking density, and customizable response temperature has been revealed. image

As one of the core courses for students majoring in chemical engineering and technology, chemical thermodynamics is closely related to physical chemistry, and the latter is the basis for learning the former.In teaching students new knowledge about chemical thermodynamics, the relevant knowledge from physical chemistry can be reviewed and explained, emphasizing the mutual penetration of physical chemistry and chemical thermodynamics.This can improve not only student understanding and mastery of chemical thermodynamics knowledge, but also the quality of teaching, thereby acquiring greater learning efficiency.In this paper, based on teaching practices in chemical thermodynamics and physical chemistry, some examples and opinions regarding the application of physical chemistry knowledge in the teaching of chemical thermodynamics are elucidated.

采用癸二酸与甘油共聚合成聚癸二酸甘油酯(PGS)做为基体,采用溶胶-凝胶法制备生物活性玻璃(BG)并与石墨烯(GR)一并做为增强体,制备了PGS/BG/GR复合材料.研究了PGS/BG/GR复合材料的力学性能、亲水性和结晶性等性能.结果表明,BG,GR均对PGS的力学性能起到了增强作用,当BG质量分数为2％,GR质量分数为5％时,PGS/BG/GR复合材料的拉伸强度为纯PGS的3.57倍、拉伸弹性模量为纯PGS的5.5倍.BG与GR的协同作用使复合材料的亲水性得到显著改善,PGS/BG/GR复合材料的接触角可达到30.7°,较纯PGS降低了58.7％.PGS/BG/GR复合材料的残炭率提高,最大结晶速率温度降低至–3.09℃.PGS/BG/GR复合材料的拉伸弹性模量和人体皮肤十分接近,其优良的亲水性有利于皮肤创伤处组织液的吸收,这种具有较高拉伸强度和亲水性的PGS/BG/GR复合材料在生物医学领域有着良好的应用前景和使用价值.

采用硅烷偶联剂(γ-甲基丙烯酰氧基丙基三甲氧基硅烷,KH-570)和纳米羟基磷灰石(n-HA)分别对微晶纤维素(MCC)表面处理.运用熔融共混方法制备改性微晶纤维素/聚乳酸(MCC/PLA)复合材料.研究了不同的MCC表面改性方法对MCC/PLA复合材料力学性能和热稳定性能的影响.结果表明:硅烷偶联剂KH-570化学包覆于MCC表面,纳米羟基磷灰石(n-HA)表面物理包覆于MCC表面,均可以使MCC的接触角增大,亲水性减弱.扫描电镜(SEM)观察到表面处理前后的MCC填料对复合材料界面影响显著;力学性能测试结果显示KH-570、n-HA表面包覆MCC能够提升聚乳酸复合材料的拉伸强度和弯曲强度.当添加量为5％(wt)时,经偶联剂处理过的MCC填充聚乳酸的材料拉伸强度达到48.74 MPa,n-HA与MCC(1 ∶1)物理包覆的MCC填充聚乳酸复合材料弯曲强度及冲击强度分别达到了 96.29MPa,0.59kJ·m-1.应力、应变试验结果显示,n-HA与MCC(1∶1)包覆改性MCC的复合材料屈服应力最大.热重分析表明经硅烷偶联剂KH-570和n-HA包覆改性可以使MCC的热稳定性提高.

采用溶液共混法制备聚乳酸/聚己内酯(PLA/PCL)复合材料,研究了四针状氧化锌晶须(T-ZnOw)对PLA/PCL复合材料的力学性能、形状记忆性能、热稳定性及降解性的影响.结果表明,当PCL质量分数为30％,T-ZnOw质量分数为3％时,PLA/PCL/T-ZnOw复合材料的拉伸强度和断裂伸长率较分别提高了40.8％、74.1％,形状记忆性能达到最佳.T-ZnOw赋予了PLA/PCL复合材料一定的抑菌性,同时还促进了复合材料的降解.PLA/PCL/T-ZnOw复合材料较PLA/PCL复合材料的结晶度(XC)提高了,形状记忆的固定率明显增加;初始热分解温度降低,残炭量提高.这种具有抑菌性的可降解PLA/PCL/T-ZnOw形状记忆材料在医疗和智能材料领域将有广泛的应用前景.

Artificial bone materials are in great need due to a lot of bone injuries. Herein, collagen/nano-hydroxyapatite (Col/nHA, C-H) composite nanospheres were obtained by in-situ mineralization, and poly L-lactic acid/ collagen/nano-hydroxyapatite (PLLA/Col/nHA, P-C-H) was further prepared by high-speed shear emulsifica-tion method. The interfacial properties and structure between PLLA and nHA are regulated by the adhesive property of Col. The morphology, structure and properties of P-C-H microsphere were characterized in detail by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and simulated degradation of PBS in vitro. The results show that C-H is uniformly distributed in P-C-H micro-spheres, and a mesoporous material with a "pomegranate" structure and a particle size of 5-30 mu m is self-assembled based on C-H multiple composite microspheres. It is beneficial to the sustained-release degradation of P-C-H and the retention/release of Ca2+. The 60-day PBS degradation shows that PLLA delays the degradation of nHA, making the degradation rate of P-C-H basically consist with the human bone healing cycle. The co -culture of P-C-H with MC3T3-E1 cells shows that P-C-H has high biocompatibility and no cytotoxicity. The cell viability is higher than 100 % in 72 h, indicating P-C-H has a proliferation effect on cell growth. Alkaline phosphatase and quantitative real-time PCR test show a positive promotion of P-C-H in cell proliferation and differentiation. The multi-layered P-C-H microspheres have an application potential in bone tissue engineering.

The preparation of bioactive materials with biomolecules as templates to control the nucleation and growth of nano-hydroxyapatite (n-HA) crystals is a vital research field in bone tissue engineering. However, meeting the performance requirements of possessing appropriate surface roughness, high porosity, structural stability, adequate mechanical strength, biodegradability and biocompatibility at the same time is the core issue that restricts the development of these biomimetic materials in biosciences as well as medical clinical translation. In this work, a mineralized self-assembled silk fibroin (SF)/cellulose interpenetrating network composite aerogel (M-S-C) material was prepared by freeze-drying using sol-gel and in situ mineralization strategy. The effects of the main factors, such as the surface properties of SF macromolecules and the change of mineralization time, on the n-HA self-assembly process and the property of M-S-C under defined conditions were explored. The properties of M-S-C, including the physicochemical properties, morphology, mechanical property, degradation behavior and in vitro cytotoxicity, were investigated to evaluate its application prospects in bone tissue engineering. M-S-C exhibits the microstructure required for an ideal cancellous bone repair material, porosity up to 99.2%, high thermal stability, moderately adjustable compressive strength (12.7-22.4 MPa), and appreciable in vitro degradation rate. Moreover, M-S-C extracts can significantly accelerate the proliferation of human embryonic kidney cells. This mineralized interpenetrating polymer network aerogel material with excellent comprehensive performance shows potential for application in bone repair and regeneration.

With the development and application of thermotropic shape memory polymer materials in the biomedical field, it is very crucial for these materials to improve their thermal conductivity efficiency and shape memory recovery rate by endowing them a high thermal conductivity. In our work, a PLA/NR/T-ZnOw/GR shape memory composite was prepared by melt blending with tetrapod zinc oxide whisker (T-ZnOw) and graphene (GR) as the double inorganic fillers and polylactic acid (PLA) and natural rubber (NR) as the polymer matrix. The synergism of T-ZnOw and GR constructs a three-dimensional (3D) thermal conductive network, making the thermal conductivity of PLA/NR/5wt%T-ZnOw/2.5wt%GR increase to 1.215 W center dot(m center dot K)(-1). The addition of T-ZnOw reduces the agglomeration of GR in the PLA/NR matrix and the interfacial thermal resistance between the fillers and the matrix. It also improves the heat transfer rate, resulting in an excellent shape memory of PLA/NR/T-ZnOw/GR with a morphology recovery rate of ca. 96%, a fixed rate of 95% and high thermal stability. The presented biodegradable shape memory composite with the 3D thermal conductive network is promising in the fields of medical treatment and intelligent sensors.

以聚乳酸(PLA)、天然橡胶(NR)为基体,四针状氧化锌晶须(T-ZnOw)为增强体,通过熔融共混的方法制备PLA/NR/T-ZnOw复合材料.考察了增强体T-ZnOw以及动态硫化(DCP)对PLA/NR/T-ZnOw复合材料力学性能、结晶性和热稳定性的影响.T-ZnOw可以使PLA/NR复合材料的力学性能、结晶度显著提高;同时赋予PLA/NR材料抑菌性.经DCP动态硫化后PLA/NR/T-ZnOw复合材料的拉伸强度、弯曲强度、冲击强度分别提高了 32.4％、33.3％、21.2％.材料热稳定性提高、结晶度下降了 88％.这种可降解聚乳酸复合材料在生物医用、医疗器械及包装材料等领域有良好的应用前景.

采用马来酸酐(MAH)作为封端剂与聚碳酸亚丙酯(PPC)进行接枝反应,制备了MAH改性聚碳酸亚丙醋(M-PPC).将M-PPC用于聚碳酸亚丙酯/聚乳酸(PPC/PLA)复合材料中,考察了MAH对PPC/PLA复合材料的力学性能、形状记忆性能和热稳定性的影响.扫描电镜(SEM)观察到M-PPC对复合材料界面影响显著,力学性能测试结果显示M-PPC对复合材料的拉伸强度和弯曲强度均有提升作用,当M-PPC含量为3％时,材料力学性能达到最佳.热重分析表明,M-PPC使PPC/PLA复合材料的初始热降解温度提高了28℃.M-PPC使PPC/PLA复合材料的热刺激相应形状回复率Rr达到93.62％,固定率Rf达到99％以上,分别比纯PPC/PLA的提高了33.58％,2.5％.

目的 制备羟丙基纳米纤维素/羟基磷灰石(NCC-HPC/HA)纳米复合材料.方法 以环氧丙烷作为改性剂,对纳米纤维素(NCC)表面进行化学修饰,获得羟丙基纳米纤维素(NCC-HPC),以提高NCC的表面疏水性及改善其分散性.在此基础上,以NCC-HPC为成核点,采用共沉淀法制备NCC-HPC/HA纳米复合材料,研究复合材料的结构与性能.结果 采用共沉淀法在改性后的纳米纤维素表面成功地合成了羟基磷灰石纳米球.由分析证实,经环氧丙烷表面改性后的NCC,几乎没有发生晶体结构变化,疏水性得到了提高,再分散性得到了改善,且能稳定存在于水和其他有机溶剂体系中,NCC-HPC与水的接触角由17°增加到55.3°.NCC-HPC/HA纳米复合材料的表面均匀分布着钙、磷元素,其Ca/P原子比为1.64,接近真实骨的钙磷比.在2 MPa条件下压制的复合材料的力学性能显示,与未经表面修饰的NCC相比,经表面修饰的纳米纤维素制备的NCC-HPC/HA纳米复合材料的力学性能有所提升.拉伸强度可达到3.48 MPa,提高了6.7％;弯曲强度可达到5.22 MPa,提高了4.4％;压缩强度可达到2.11 MPa,提高了4.7％.结论 经羟丙基改性的NCC,疏水性得到提高,在水溶液中的分散性明显改善.以此为基础制备的NCC-HPC/HA纳米复合材料中,球状纳米羟基磷灰石(n-HA)均匀分布在线状NCC-HPC上,具有较好的力学性能和热稳定性,适用于骨组织工程应用.

Composites materials comprised of biopolymeric aerogel matrices and inorganic nano-hydroxyapatite (n-HA) fillers have received considerable attention in bone engineering. Although with significant progress in aerogel-based biomaterials, the brittleness and low strengths limit the application. The improvements in toughness and mechanical strength of aerogel-based biomaterials are in great need. In this work, an alkali urea system was used to dissolve, regenerate and gelate cellulose and silk fibroin (SF) to prepare composite aerosol. A dual network structure was shaped in the composite aerosol materials interlaced by sheet-like SF and reticular cellulose wrapping n-HA on the surface. Through uniaxial compression, the density of the composite aerogel material was close to the one of natural bone, and mechanical strength and toughness were high. Our work indicates that the composite aerogel has the same mechanical strength range as cancellous bone when the ratio of cellulose, n-HA and SF being 8:1:1. In vitro cell culture showed HEK-293T cells cultured on composite aerogels had high ability of adhesion, proliferation and differentiation. Totally, the presented biodegradable composite aerogel has application potential in bone tissue engineering.

以经硅烷偶联剂(KH570)处理的微晶纤维素(MCC)为填料,三嗪系膨胀阻燃剂(CFA)与聚磷酸铵(APP)的复配体系为阻燃剂(C-IFR),聚乳酸(PLA)为基体树脂,采用熔融共混方法制备阻燃MCC/PLA复合材料,研究了MCC对阻燃PLA复合材料的力学、阻燃性能、热稳定性的影响.力学试验结果显示,MCC加入使PLA和阻燃PLA均比纯基体树脂的拉伸强度、弯曲强度有所降低,对悬臂梁缺口冲击强度影响小.MCC在小添加量时可以提高PLA复合体系的极限氧指数,MCC与APP具有的协同效应降低了PLA的燃烧速率,提高了材料的成炭性能.热降解动力学表明,MCC增加了PLA和阻燃PLA材料的活化能,提高了PLA复合材料的热稳定性,同时MCC降低PLA的玻璃化转变温度.

In order to produce an alternative energy of biodiesel using field pennycress (Thlaspi arvense L.) seed oil, a novel Fe3O4/graphene oxide-phenylalanine bisulfate ionic liquid core-shell magnetic catalyst was developed. Ferro ferric oxide nanoparticles and graphene oxide (GO) were employed to prepare a magnetic carrier of Fe3O4@GO nanocomposite which applied to immobilize phenylalanine bisulfate ionic liquid (PBIL). The immobilized PBIL was characterized by the means of characterization. The heterogeneous Fe3O4@GO@PBIL catalyst was demonstrated to have a high catalytic efficiency that reached 92.38 % of biodiesel yield under the optimal conditions (methanol/oil molar ratio of 10:1, reaction temperature of 60 degrees C, reaction time of 4 h, catalyst dosage of 25 wt%, stirring speed of 1500 r/min). After transesterification processes, the catalyst could be easily removed from the reaction mixture with an external magnet and showed little deactivation after multiple recycles. The main properties of biodiesel product were reconcilable with the range of test standards of ASTM D6751 and EN 14214. In summary, the prepared Fe3O4@GO@PBIL catalyst behaved a superiorly catalytic performance, which made the produced biodiesel possess the possibility of application to biofuel as an ideal substitution.

A screw extrusion treatment method successfully applies to the extraction of essential oils from Pinus pumila barks under microwave-assisted hydrodistillation conditions, which effectively promotes the increase of the yield of essential oils. Moreover, some potential factors affecting the yield of essential oils have been systematically analyzed and optimized through single factor screening method and Box-Behnken design, and the optimum operating conditions were liquid-solid ratio 5.82 mL/g, microwave irradiation power 585 W, and microwave irradiation time 30 min. Meanwhile, the satisfactory yield of essential oils was 16.51 ? 0.83 mL/kg in the derived optimum conditions, which was highly consistent with the predicted result (17.14 mL/kg) by the BoxBehnken design model. By comparing the kinetic curves of the separation of essential oils by different methods, the bark after the screw extrusion process can obtain higher yield and separation efficiency of essential oils through the microwave-assisted hydrodistillation method. The antioxidant properties and the yield of the essential oils separated by different methods were compared, and the antioxidant capacity and the yield of the essential oils obtained from the barks that were processed by screw extrusion treatment were significantly better than other treatment methods. By comparing the raw materials obtained by different treatment methods and their residues after essential oil separation, it was confirmed that the screw extrusion treatment method greatly increases the yield of the essential oils. The results show that the introduction of screw extrusion treatment and microwave-assisted hydrodistillation in the separation of essential oil has produced significant changes, which may become a new type of essential oil separation technology and be applied to the market.

在高压反应釜中,以发烟硫酸为溶剂,碘为催化剂,温度为443～473K、甲烷压力3.0MPa的条件下进行了甲烷气-液氧化反应.通过对实验数据的拟合得出本征动力学反应速率方程为:-rA=kCA,其中,443K、453K、463K和473K温度下的反应速率常数分别为0.0271、0.0284、0.0344和0.0391,活化能E为22.49kJmol-1,频率因子k0为11.75min-1.

Visible-light-induced controlled radical polymerization of methacrylates by using zirconium-porphryinic metal–organic frameworks.

Phototoxic treatments of pathogenic bacteria and fungi of trees induce oxidative damage that is preferable to toxic chemical treatment. Here, we used green methods to synthesize Chlorin e6 from chlorophyll a, which was extracted from crude silkworm excrement using concentrated (strong) alkali hydrolysis and acidification. The photosensitive bactericidal activities of the new chlorin were tested in vitro, and possible mechanisms of action are discussed. The results showed that Chlorin e6 can be light-activated to have bactericidal activity against Escherichia coli, Bacillus subtilis and Fusarium oxysporum, but it had little bactericidal effect in the dark. This kind of chlorin compounds has great potential as a natural phototoxic antimicrobial compound to control harmful bacteria on the leaves in forestry systems.

以四水硝酸钙与磷酸氢二铵为原料,采用共沉淀法制鲁了壳聚糖-羟基磷灰石(CS-HA)复合微球,并通过熔融共混法将其与聚乳酸(PLA)复合制得PLNCS-HA复合材料,同时分析了CS-HA复合微球的结构以及PLNCS-HA复合材料的性能.结果 表明:CS已成功与HA复合,制得具有自组装微球结构的CS-HA复合物.当CS-HA复合微球添加量为5％时,PLA/CS-HA复合材料的弯曲强度较纯PLA提高了15.1％,较同填充量的PLA/HA复合材料提高了13.5％,而拉伸强度和冲击强度较纯PLA略有降低.此外,当CS-HA复合微球添加量为5％时,PLA/CS-HA复合材料的5％质量损失温度和失重速率峰值温度较纯PLA分别提高了33.1和22.2℃,说明CS-HA复合微球的加入提高了PLA的热稳定性;当CS-HA复合微球添加量为15％时,PLA/CS-HA复合材料的结晶度达到31.72％,较纯PLA提高了23.23％,这说明CS-HA复合微球可促进PLA的结晶.