Novel SilverPolyurethane Nanocomposite by In Situ
Silver nanocrystals by hyperbranched polyurethane-assisted photochemical reduction of Ag+
Materials Chemistry and Physics81(2003)104–107Silver nanocrystals by hyperbranched polyurethane-assistedphotochemical reduction of Ag+H.W.Lu,S.H.Liu,X.L.Wang,X.F.Qian∗,J.Yin,Z.K.ZhuResearch Institute of Polymer Materials,School of Chemistry and Chemical Technology,Shanghai Jiao Tong University,Shanghai200240,PR ChinaReceived11April2002;received in revised form4March2003;accepted4March2003AbstractSilver nanoparticles in hyperbranched polyurethane(HP)matrix were prepared by means of UV irradiation at room temperature.HP was found to play a key role in the photochemical reduction of silver ions and the formation of nanosized particles.Transmission electron microscopic(TEM)analysis showed that silver nanoparticles were homogeneously dispersed in HP matrix.The absorption peaks due to the surface plasmon resonance of the obtained silver nanoparticles were observed at about430nm in the ultraviolet-visible(UV-Vis) absorption spectra.X-ray powder diffraction(XRD)was also used to characterize the obtained nanoparticles.©2003Elsevier Science B.V.All rights reserved.Keywords:Nanostructures;Polymers;Optical properties1.IntroductionIn the past decade,nanoparticles of noble metals havebeen investigated intensively due to their potential applica-tions in microelectronics[1–3],and their optical,electric,and catalytic properties[4–6].Many wet chemical methods,which include solid–liquid-phase arc discharge[7],ultravi-olet irradiation photoreduction[8],and a pulse sonoelectro-chemical method[9]have been reported for the synthesis ofmetal nanoparticles.Recently,the application of dendrimers,which haveunique structures and properties,has opened a new way ofproducing metal nanoparticles with small size and narrowsize distribution[7,10].Dendrimers usually take a sphericalthree-dimensional structure,which is very different fromlinear polymers adopting a random-coil structure,so den-drimers might provide reaction sites including their interioror periphery[11].Till now,many nanoparticles synthesizedin dendrimers have been reported[11–13].For example,Esumi et al.prepared nanoparticles of gold,platinum,andsilver by reduction of their metal salts with NaBH4in thepresence of poly(amidoamine)dendrimers[11].However,the synthetic scheme of dendrimers which have a welldefined and perfectly branching structure is usually com-∗Corresponding author.Tel.:+86-21-54743268;fax:+86-21-54741297.E-mail address:xfqian@(X.F.Qian).plicated.As an alternative,hyperbranched polymers can beprepared by a much easier process.Although having a lessperfect structure than dendrimers,hyperbranched polymersstill maintain many of the architectural features found intheir more perfectly defined dendritic counterparts and aresupposed to exhibit properties resembling those of den-dritic ones[14,15].It is surprising,however,that reportson the preparation of metal nanoparticles in hyperbranchedpolymers are still limited.Herein,we presented a hyperbranched polyurethane(HP)-assisted photochemical method for producing silvernanoparticles by means of UV irradiation.It was found thatthe silver nanoparticles were homogeneously dispersed inthe HP matrix and exhibited an UV-Vis absorption peak,corresponding to the characteristic surface plasmon reso-nance of silver particles.2.ExperimentalAll the reactants and solvents were of analytical grade.HPwas synthesized according to[16].A250W high-pressuremercury lamp was used as the ultraviolet irradiation source.In a typical preparation process,0.1g AgNO3was dissolvedin the solution of0.5g HP dissolved in20ml ethanol un-der vigorous stirring.The solutions were then irradiated for4,24,and36h,respectively under ultraviolet irradiation atroom temperature.The obtained black viscous solution was0254-0584/03/$–see front matter©2003Elsevier Science B.V.All rights reserved.doi:10.1016/S0254-0584(03)00147-0超支化聚氨酯光化学照射表面等离子共振贵金属－－－银金属纳米颗粒的合成方法Edited by Foxit ReaderCopyright(C) by Foxit Software Company,2005-2007For Evaluation Only.树枝水银灯紫外照射不同时间：４，２４，３６小时H.W.Lu et al./Materials Chemistry and Physics 81(2003)104–107105stable and did not precipitate within 3months.The resulting solution was casted on a glass substrate and dried at room temperature for 12h,then at 30◦C in vacuum for 12h.Black films were peeled off for characterization.The X-ray powder diffraction (XRD)patterns were recorded at a scanning rate of 4◦min −1in the 2θrange of 20–60◦using a Rigaku D/max ␥A X-ray diffractome-ter with Cu K ␣radiation (λ=1.54178Å).Transmission electron microscopic (TEM)photographs were taken on a Hitachi S-530TEM.Ultraviolet-visible (UV-Vis)spec-tra were measured on a Perkin-Elmer Lambda 20UV-Vis spectrophotometer.A Perkin-Elmer Paragon 1000FTIR spectrophotometer was used for FTIR measurement.3.Results and discussion 3.1.XRD analysisFig.1showed the typical XRD patterns of the obtained samples.All the diffraction peaks could be indexed to face-centered cubic silver phase with cell constants a 0=4.1Å.The values were close to those in the JCPDS card (card no.4-783).The average crystalline size,which was determined from the half-width of the diffraction using the Debye–Scherrer equation,approximately 8nm.3.2.TEM analysisFig.2showed the TEM micrographs of the as-prepared silver nanoparticles.The obtained silver nanoparticles were well dispersed in HP,with different diameters of 5–10nm and 15–20nm,respectively.The size of the smaller particles (5–10nm)was consistent with XRD results.The larger silver particles (15–20nm)were probably the aggregates of the smaller ones,due to the high surface energy of the nanosizedcrystals.Fig.1.XRD pattern of silver nanoparticles obtained in the presence of HP after 24h irradiationtime.Fig.2.TEM micrograph of silver nanoparticles obtained in the presence of HP after 24h irradiation time.3.3.UV-Vis spectraThe generation of silver nanoparticles could also be iden-tified from both the color change and the UV-Vis spectrum of the as-prepared products.Upon irradiation of the solution containing HP and Ag +,coloration was observed.Fig.3showed the UV-Vis absorption spectra of the silver nanopar-ticles obtained in the presence of HP with different irradia-tion time.Pure HP solution exhibited nearly no absorption in the selected region.The absorption band at about 430nm may be attributed to the characteristic surface plasmon res-onance of silver nanoparticles [17].By increasing the irra-diation time,the peaks around 430nm shifted to the lower剥离Edited by Foxit ReaderCopyright(C) by Foxit Software Company,2005-2007For Evaluation Only.106H.W.Lu et al./Materials Chemistry and Physics 81(2003)104–107Fig.3.UV-Vis absorption spectra of silver nanoparticles obtained in the presence of HP after different irradiation time.(a)0h;(b)4h;(c)24h and (d)36h.wavelengths (blue shift).This effect may be explained by the increasing electron density on the silver particles due to alteration of the Fermi level [18].In contrast,the AgNO 3solution in the absence of HP was irradiated in the same conditions (Fig.4),but no coloration and absorption band characteristic of surface plasmon reso-nance were observed.It was conceivable that HP played a key role in the photochemical reduction of Ag +.It may be due to the coordination between HP and Ag +,which may decrease the potential of Ag +/Ag (E Ag +/Ag )and promote the reduction of Ag +.3.4.FT-IR spectraTo further confirm the interaction between HP and Ag +,the infrared spectra were measured.As could be seen in Fig.5,the absorption C =O stretching peak ofHPFig.5.FT-IR transmittance spectra of pure HP (a)and Ag +-doped HP(b).Fig.4.UV-Vis absorption spectra of silver nanoparticles obtained in the absence (a)and presence (b)of HP after 36h irradiation time.at 1719cm −1shifted to 1715cm −1after the addition of AgNO 3,indicating that there was coordination between HP and Ag +.4.ConclusionThis work presented an HP-assisted photochemical method for producing silver nanoparticles by means of UV irradiation.X-ray diffraction results showed that a pure face-centered cubic silver phase was obtained in the as-prepared nanoparticles.TEM analysis showed that silver nanoparticles were homogeneously dispersed in HP matrix.In the UV-Vis absorption spectra of the obtained nanopar-ticles,the absorption peak due to the surface plasmon reso-nance of silver particles was observed at about 430nm.HP was found to play a key role in the photochemical reduction of silver ions and the formation of nanosized particles.H.W.Lu et al./Materials Chemistry and Physics81(2003)104–107107AcknowledgementsThis work wasfinancially supported by the National Nat-ural Science Foundation of China(50103006),the Min-istry of Education of China and the Shanghai Shu Guang 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不同硫化体系对混炼型聚氨酯橡胶性能的影响
作者简介：杜伟（1996-），男，在读硕士研究生，主要从事橡胶共混与改性方面的研究。
收稿日期：2022-06-02混炼型聚氨酯橡胶（MPU ）是由聚酯或聚醚与异氰酸酯类化合物聚合而成的高分子聚合物[1]。
在各种橡胶中耐磨性最高。
强度、弹性高，耐油性好，耐臭氧、耐老化、气密性等也都很好[2]。
常用于制作轮胎及耐油、耐苯零件、垫圈防震制品等[3~4]。
MPU 与传统聚氨酯（TPU 、CPU 等）相比最大的特点是，MPU 可以像传统橡胶一样通过加入硫化体系、补强体系等对它进行加工、硫化、补强等。
MPU 的硫化体系主要有硫磺、过氧化物、异氰酸酯三大类：硫磺硫化时硫化剂用量一般为1.5~2份，促进剂常用M 和DM ，并且促进剂用量增加会延长焦烧时间，硫磺硫化得到的硫化制品综合性能较好。
过氧化物硫化时，过氧化二异丙苯（DCP ）是最普遍的过氧化物硫化剂，硫化得到的制品压缩永久变形小，弹性和耐老化性能均较好，缺点是不能用蒸汽直接硫化，撕裂强度较差。
MPU 也可以用TDI 及其二聚体、MDI 及其二聚体等异氰酸酯类硫化剂硫化，生成脲基甲酸酯键交联键，可以制得耐磨性良好、强度高、硬度较大的制品。
近年来国内市场涌现了一批新型高性能混炼型聚氨酯材料，MPU E6008是具有代表性的一款，展开对MPU 硫化体系的研发与探索，也迎合了国内市场的需求。
本实验分别对硫磺硫化体系和过氧化物硫化体系硫化的MPU 进行了考察与研究。
不同硫化体系对混炼型聚氨酯橡胶性能的影响杜伟，邓涛*(青岛科技大学 高分子科学与工程学院，山东 青岛 266042)摘要：本实验探索了不同硫化体系对混炼型聚氨酯橡胶（MPU ）的性能的影响，实验发现，硫磺硫化体系和过氧化物硫化体系的MPU 硫化胶性能各有特点，硫磺硫化MPU 的拉伸性能和耐磨性能较好，过氧化物硫化MPU 的定伸应力更大，扯断永久变形更小。
此外，硫磺硫化体系的耐热空气老化性能更好，而过氧化物硫化MPU 的耐热非极性油和高温性能更为优异。
银纳米水凝胶文献综述
北京化工大学北方学院NORTH COLLEGE OF BEIJING UNIVERSITY OFCHEMICAL TECHNOLOGY（ 2014 ）届本科生毕业设计（论文）文献综述题目：银纳米水凝胶的制备及表征学院：化工与材料工程学院专业：应用化学学号： 100130075 姓名：李晴指导老师：冯献起顾明广教研室主任（负责人）：顾明广2014 年 5 月17 日文献综述前言本人毕业设计的论题为《银纳米水凝胶的制备及表征》。
水凝胶的开发与研究也是探索智能材料的一个重要方向，银纳米水凝胶特殊性能也成了众多学者重点研究对象；大量的文献对银纳米粒子及其水凝胶的制备方法做出了介绍，并深入的研究了纳米银粒子的引入对水凝胶性能的影响；本文将在学习其研究成果的基础上，对银纳米水凝胶的制备及表征等方向做进一步的研究探索。
本文根据国内外学者对银纳米水凝胶的研究成果，借鉴他们的成功经验，在银纳米水凝胶研究中作出新的探索实验，这些文献给本文很大的参考价值。
本文主要查阅近几年有关银纳米及水凝胶方向研究的期刊文献。
灵敏材料，是能够感觉到环境或者它们自身状态变化，根据已有的目标作出判断，然后改变其功能的材料。
作为灵敏材料最重要的一个分支，形状记忆材料包括形状记忆合金，形状记忆陶瓷和形状记忆聚合物。
1941年，Vernon首次提出形状记忆的概念，然而，直到1960s，将交叉链式聚乙烯用于制作高温收缩管和胶片时，人们才认识到形状记忆的重要性。
1980s后期开始，主要致力于对形状记忆聚合物开发，1990s得到加速发展，仅在过去5-10年当中，就取得有重大意义的进展[1]。
众所周知，金属纳米材料在力学、光学、催化以及热学和电学等多方面，相对于传统材料而言，有着特殊性能，成为最具研究价值的功能材料。
水凝胶是一种能够溶胀于水中，而不会溶解的大分子聚合物，有较好的生物相容性和机械性能，在生物医学、形状记忆等众多领域有着广泛的应用。
传统的银离子有着很强的杀菌性能，而纳米银杀菌能力远大于银离子。
高密度聚乙烯_蒙脱土复合材料的制备及性能的研究
由于马来酸酐上的羧基和蒙脱土上的胺基相互作用使A G<0,同时极性的
高密度聚乙烯/蒙脱土复合材料的制备及性能的研究
作者:曲静波
学位授予单位:青岛科技大学
1.柯扬船.皮特·斯壮聚合物--无机纳米复合材料 2002
2.刘吉平.郝向阳纳米科学与技术 2001
3.都有为超微颗粒的物理特性[期刊论文]-材料导报 1992(5)
36.舒文艺功能性聚烯烃的开发现状[期刊论文]-塑料 1995(4)
37.漆宗能.马永梅.张世民.张泽源.岳群纳米塑料[期刊论文]-石化技术与应用 2001(5)
38.张国耀.易国祯.吴立衡.徐翔.宋青.杨宇.金剑.钟淑芳.漆宗能聚对苯二甲酸乙二酯/蒙脱土纳米复合材料的制备和性能[期刊论文]-高分子学报 1999(3)
10.Moet A.Akelah A Polymer-clay nanocomposites: polystyrene grafted onto montmorillonite interlayers 1993
11.Kato C查看详情 1989
12.Aranda P.Ruiz_Hitzky E Poly(ethylene oxide)-silicate intercalation materials 1992
4.Birriiner R.Gleiter H Structure of Nanocomposites 1984
5.张立德.牟季美纳米材料和纳米结构 2001
6.Okada A.Kawasumi M.Kurauchi T查看详情 1987
7.Giannelis E P Polymer Layered Silicate Nanocomposites 1996
对电极涂覆AgNWs对聚3-(2-羟乙基)噻吩变色性能的影响
第41卷第2期2021 年4 月西 安 工 业 大 学 学 报JournalofXi 'anTechnologicalUniversityVol. 41 No. 2Apr2021DOI ： 10. 16185/j. jxatu. edu. cn. 2021. 02. 002http : //xb. xatu. edu. cn对电极涂覆AgNWs 对聚3-(2-羟乙基)噻吩变色性能的影响** 收稿日期:2020-08-16基金资助：陕西省自然科学基础研究计划项目(2019JM-225)。
第一作者简介：王 潇(1996-),女，西安工业大学硕士研究生。
通信作者简介：张文治(1980-)男，西安工业大学副教授，主要研究方向为光电功能材料与器件,E-mail :zhangwz @xatu. edu. cn 。
引文格式：王潇，张文治.对电极涂覆AgNWs 对聚3-(2-羟乙基)噻吩变色性能的影响西安工业大学学报,2021,41(2):132-139.WANG Xiao,ZHANG Wenzhi. Influence of Coating Silver Nanowires on Counter Electrode on the Electrochromic Proper ties of Poly(3-thiopheneethanol ) )J]. Journal of Xi an Technological University , 2021,41(2) : 132-139.王潇，张文治(西安工业大学材料与化工学院，西安710021)摘要：为提高聚噻吩类衍生物电致变色器件的响应速度和循环稳定性，采用电化学聚合法制备聚3-(2-^乙基)噻吩(P3TE )薄膜，同时将银纳米线(AgNWs )分散液滴涂到ITO 玻璃上制得AgNWs 导电薄膜，分别以ITO 玻璃上的P3TE 和AgNWs 薄膜为工作电极和对电极，与凝胶电解质一起组装成电致变色器件。
毕业论文外文翻译-负载银的掺氮石墨烯概论
学号：10401604常州大学毕业设计（论文）外文翻译（2014届）外文题目Easy synthesis of nitrogen-doped graphene–silvernanoparticle hybrids by thermal treatment ofgraphiteoxide with glycine and silver nitrate 译文题目通过水热处理氧化石墨烯、甘氨酸和硝酸银简便地合成掺氮石墨烯-银纳米粒子复合物外文出处CARBON50(2012)5148–5155学生王冰学院石油化工学院专业班级化工106校内指导教师罗士平专业技术职务副教授校外指导老师专业技术职务二○一四年二月通过水热处理氧化石墨烯、甘氨酸和硝酸银简便地合成氮杂石墨烯-银纳米粒子杂合物Sundar Mayavan,Jun-Bo Sim,Sung-Min Choi摘要：氮杂石墨烯-银纳米粒子杂合物在500℃通过水热处理氧化石墨烯（GO）、甘氨酸和硝酸银制得。
甘氨酸用于还原硝酸根离子，甘氨酸和硝酸根混合物在大约200℃分解。
分解的产物可作为掺杂氮的来源。
水热处理GO、甘氨酸和硝酸银混合物在100℃可形成银纳米粒子，200℃时GO还原，300℃时产生吡咯型掺氮石墨烯，500℃时生成吡咯型掺氮石墨烯。
合成物质中氮原子所占百分比为13.5%.在合成各种纳米金属粒子修饰的氮杂石墨烯方面，该合成方法可能开辟了一个新的路径，其在能量储存和能量转换设备方面很有应用价值。
1.引言石墨烯是所有石墨材料的基本构件，其蜂窝状晶格由单层碳原子排列而成。
它表现出与结构有关的独特电子、机械和化学性质，具有较高的比表面积（2630-2965m2g-1）[1–3]。
化学掺杂杂原子石墨烯像掺杂氮原子，极大地引起了人们的兴趣，因其在传感器、燃料电池的催化剂和锂离子电池的电极等方面具有应用潜力[4–6]。
氮原子的掺杂改变了石墨烯的电子特性和结构特性，导致其电子移动性更强，产生更多的表面缺位。
十二硫醇修饰银纳米颗粒用途
十二硫醇修饰银纳米颗粒用途一、银纳米颗粒的制备方法银纳米颗粒是一种尺寸在1到100纳米之间的纳米材料，其具有较大的比表面积和特殊的光、电、磁等性质，因此在科学研究和工业应用中具有广泛的应用前景。
在制备银纳米颗粒时，常用的方法有化学还原法、光化学法、生物合成法等。
其中，化学还原法是最常用的方法之一。
在这个方法中，我们可以通过将银盐与还原剂（如氢气、葡萄糖等）反应来生成银纳米颗粒。
这种方法制备的银纳米颗粒尺寸均一、稳定性好，适用于大规模生产。
二、十二硫醇修饰银纳米颗粒的表面修饰为了提高银纳米颗粒的稳定性和生物相容性，常常需要对其表面进行修饰。
十二硫醇（即十二烷硫醇）是一种疏水性有机分子，其结构中含有硫原子，可以与银纳米颗粒表面的银原子形成化学键。
通过十二硫醇的修饰，可以使银纳米颗粒在水相中分散稳定，并且可以进一步与其他功能性分子进行偶联，实现多功能化修饰。
三、十二硫醇修饰银纳米颗粒在生物医学领域的应用1. 抗菌剂和消毒剂：银纳米颗粒具有良好的抗菌性能，可以用于制备抗菌剂和消毒剂。
其通过与细菌细胞膜和DNA相互作用，破坏细菌的生物功能，从而实现抗菌效果。
2. 药物传递系统：银纳米颗粒可以作为药物的载体，通过控制其尺寸和表面修饰来实现对药物的包封和释放。
这种药物传递系统可以提高药物的生物利用度和靶向性，减少副作用。
3. 诊断试剂：银纳米颗粒具有特殊的光学性质，可以通过改变其尺寸和形状来调节其表面等离子共振吸收峰的位置和强度。
这使得银纳米颗粒可以作为生物传感器、免疫分析试剂等用于疾病诊断的重要试剂。
四、十二硫醇修饰银纳米颗粒在催化领域的应用1. 催化剂：银纳米颗粒具有良好的催化性能，在有机合成和环境保护等领域有广泛的应用。
通过十二硫醇的修饰，可以调控银纳米颗粒的形状和表面活性位点，从而提高其催化活性和选择性。
2. 氧化反应：银纳米颗粒可以作为氧化剂用于有机合成中氧化反应的催化剂。
其具有高的氧化能力和良好的催化效果，可以实现对醇、醛、酮等有机物的选择性氧化。
三种纳米改性剂对聚氨酯仿木材料抗弯抗压性能影响的对比研究(下)
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Novel Silver/Polyurethane Nanocomposite by In Situ Reduction:Effects of the Silver Nanoparticles on Phase and Viscoelastic BehaviorM.COCCA,L.D’ORAZIOIstituto di Chimica e Tecnologia dei Polimeri del CNR,Via Campi Flegrei 34,Fabbricato 70,80078Pozzuoli,Napoli,ItalyReceived 13February 2007;revised 18July 2007;accepted 17August 2007DOI:10.1002/polb.21308Published online in Wiley InterScience ().ABSTRACT:A novel silver/poly(carbonate urethane)nanocomposite was preparedthrough in situ reduction of a silver salt (AgNO 3)added to a solution consisting of a commercial poly(carbonate urethane)dissolved in N,N -dimethylformamide (DMF).In this system,the presence of the poly(carbonate urethane)was proved to protect the silver nanoparticles,whose formation was confirmed by means of UV–vis spectros-copy,from aggregation phenomena.The silver morphology developed in the solidstate after DMF casting was imaged by FESEM.Homogeneous dispersion of silvernanoprismsin the poly(carbonate urethane)matrix was clearly observed.The effects of dispersion of silver nanoparticles within the poly(carbonate urethane)matrix were investigated by means of ATR-FTIR and multifrequency dynamic mechanical thermal analyses.The obtained results revealedthat the presence of silver nanoparticles modifies both the phase and the viscoelastic behaviors of poly(carbonate urethane).As a matter of fact,the hydrogen bond formation in the hard and soft segments was found to be hindered and the molecular motions of the soft segments were restricted,because a comparatively higher activation energy was required for the relateda -relaxation process.VC 2008Wiley Periodicals,Inc.J Polym Sci Part B:Polym Phys 46:344–350,2008Keywords:DMF reduction;DMTA;FTIR;nanocomposite;phase separation;poly(carbonate urethane);polyurethane;silver;viscoelastic propertiesINTRODUCTIONThe investigation of metal nanoparticles has been an extremely active area in the last years for their use as advanced materials with novel electronic,magnetic,optic,thermal,and cata-lytic properties as well as for their technological and biological applications.1–3Hence,a variety of routes such as photolitic reduction,4radiolytic reduction,5,6sonochemical method,7solvent extrac-tion reduction,8microemulsion techniques,9pol-yol process,10alcohol reduction,11and organicsolvent reduction were reported for the prepara-tion of metal nanoparticles (Pt,Pd,Au,andAg).12Several examples exist on the reduction of metallic salts by organic solvents,mainly ethanol.In particular,for silver salts N,N -di-methylformamide (DMF)was found to act as a powerful reductant.13,14Metal/polymer nanocomposites presently rep-resent one of the most interesting and challeng-ing research ually,these nanocompo-sites are prepared through blending nanometer metal particles with polymer,15reduction of polymer–metal ion complexes or metal ions in the polymer solutions with reducing agents,16,17and reduction of metal ions with the aid Correspondence to:L.D’Orazio (E-mail:dor@r.it)Journal of Polymer Science:Part B:Polymer Physics,Vol.46,344–350(2008)VC 2008Wiley Periodicals,Inc.344均匀的棱柱这个到底是么子啊？irradiation.18,19In all these cases,the polymeric matrix phase was used to control the particle shape and size and particle size distribution,which are crucial factors in determining the nanocomposite properties.However,in many cases,the phenomena of aggregation of the nanoparticles occur in the polymer processing.16In this work,we report on the preparation of a novel silver/poly(carbonate urethane)nano-composite and on the effects of the silver nano-particles on the phase and viscoelastic behavior of the poly(carbonate urethane).In particular,a commercial water-dispersed poly(carbonate ure-thane)(trade name Idrocap 994;ICAP-SIRA,Parabiaco,Milano,Italy)was used as the poly-meric matrix for nanocomposite preparation.Generally,Idrocap 994was used for textile fin-ishing,by coating and padding on fabrics;this material was selected in the framework of our research aimed at setting up nanotechnologies for textiles.The silver/poly(carbonate urethane)nanocom-posite was achieved by a single-step procedure:the silver salt was added to the poly(carbonate urethane)dissolved in DMF,which acts as both a solvent and an in situ reductant.The genera-tion of silver nanoparticles was monitored by UV–vis absorption peak corresponding to their characteristic surface plasmon resonance.The silver morphology developed in the solid state after DMF casting was imaged by FESEM.ATR-FTIR was then applied to evaluate the degree of hydrogen bonding in plain poly(car-bonate urethane)and silver/poly(carbonate ure-thane)nanocomposite,whereas the related viscoelastic behavior was analyzed by multifre-quency DMTA.EXPERIMENTALMaterialsThe raw materials used in this work are as fol-lows:AgNO 3was purchased from Aldrich;DMF was supplied by LabScan;a linear aliphatic poly (carbonate urethane)(trade name Idrocap 994)was prepared,following the prepolymer mixing process,in water dispersion by ICAP-SIRA (Par-abiaco,Milano,Italy).Prepolymer is formed by reacting polycarbonate diol,M w ¼2000,with a molar excess of isophorondiisocyanate (IPDI),M w ¼222.29;in this reaction mixture,an inter-nal emulsifier 2,2-bis(hydroxymethyl)propionicacid (DMPA)is added to allow the dispersion of the polymer in water.After polymerization,the resin is dispersed in hot water in the presence of triethylamine.The M w values of the poly(car-bonate urethane)so achieved are in the range between 30,000and 50,000in GPS with stand-ard PS.All the reactants and solvents were used as received.MethodSilver/poly(carbonate urethane)nanocomposite was prepared following a patented method.20About 0.1g of AgNO 3was dissolved in a solu-tion of 0.5-g Idrocap 994dissolved in 20-mL DMF and vigorously stirred for 10min at 258C.The resulting solution was poured into Petri dishes at room temperature and DMF was cast at 308C for 24h.The film obtained (thickness $60l m)was washed with deionized water before characterization.Experimental TechniquesThe generation of silver nanoparticles was moni-tored by means of UV–vis spectra of the as-prepared solution after 10,20,30,60,120,and 240min.The UV–vis spectra were recorded by means of a Jasco V-570spectrophotometer equipped with a 10-mm quartz cell.The silver mode and state of dispersion into the polymeric matrix were investigated by means of a Fei Quanta 600field emission envi-ronmental scanning electron microscope (ESEM)operating in a low-vacuum mode at 10kV and a working distance of 4.8mm.Attenuated total reflection Fourier-transform infrared spectroscopy was performed on the films of plain poly(carbonate urethane)and silver/poly(carbonate urethane)nanocomposite.The spectra were collected through Jasco FTIR 6300spectrometer using single-reflection micro-ATR accessory with diamond ATR element.Spectral resolution was 4cm À1.The viscoelastic behavior of the plain poly (carbonate urethane)and the silver/poly(carbon-ate urethane)nanocomposite was analyzed through multifrequency dynamic mechanical thermal analy-sis (DMTA).Such tests are carried out using a Perkin Elmer Pyris Diamond DMA apparatus.The experiments are performed in tensile mode at frequencies of 0.05,0.1,0.2,0.5,1,2,5,10,and 20Hz,at a heating rate of 0.58C/min andNOVEL SILVER/POLYURETHANE NANOCOMPOSITE345Journal of Polymer Science:Part B:Polymer Physics DOI 10.1002/polb乳化剂树脂红外可以用来估算氢键的程度哈in a temperature range fromÀ100to1008C. Samples of20-mm length,10-mm width,and $60-l m thickness were used.The storage modulus(E0),loss modulus(E@),and loss tangent (tan d)were recorded.RESULTS AND DISCUSSIONFormation of Ag NanoparticlesFigure1shows the evolution of the UV–vis spectra of silver nanoparticles obtained in the presence of Idrocap994.Pure Idrocap994solu-tion exhibits nearly no absorption in the selected region.The absorption band occurs at near450nm indicating that Ag1ions are reduced to Ag0in the as-prepared solution,21the intensity of the band increasing with the reaction time.Such an increase could be associated with an increase in the size of the silver nanoparticles.22Moreover, as the reaction proceeds,the absorbance tail(at high wavelengths)rises from zero suggesting a transition from separate nanoparticles to bulk silver metal.14The solution of AgNO3in DMF(i.e.,in ab-sence of Idrocap994)was stirred and monitored in the same conditions as applied in the pres-ence of Idrocap994.The time evolution of the UV–vis spectra of this solution is shown in Figure2.As shown in Figure2,the spectra exhibit a strong absorption band close to417nm demon-strating that Ag1ions are reduced to Ag0in DMF.Note that the intensity of the absorption band decreases with increasing the time indicat-ing the occurrence of a particle aggregation pro-cess.23A comparison of Figures1and2,therefore, indicates that the presence of Idrocap994 assists Ag1ions reduction process by stabilizing the silver nanoparticles.Hence,a possible dis-persion of the formed Ag nanoparticles within poly(carbonate urethane)matrix could be mod-eled as reported in Scheme1.FESEM AnalysisFigure3shows the FESEM micrograph of the silver/poly(carbonate urethane)film observed without performing any surface treatment.As shown,silver nanoprisms(mainly triangular and polygonal)are homogeneously dispersed in the polymeric matrix,thus demonstrating the effectiveness of the preparation method.FTIR AnalysisFigure4shows typical ATR-FTIR spectra of the poly(carbonate urethane)without[Fig.4(A)]and with nanosilver[Fig.4(B)].Considering thatÀÀNH groups in urethane linkage are able to form hydrogen bonds with urethane carbonyl and carbonate carbonyl in poly(carbonate urethane),a careful examination ofÀÀNH and carbonyl peaks was performed to investigate the morphology of the hard and soft segments.24As shown in Figure4,a stretching band was observed near3324cmÀ1corresponding to the hydrogen-bonded NÀÀH stretching vibration.A free(not hydrogen-bonded)NÀÀH stretching band absorbing at3400–3500nm was weakly observed.This indicates that most of the amideFigure1.Time evolution of the UV–vis spectra of the reduction process undergone by Ag1ions in the presence of Idrocap994.Figure2.Time evolution of the UV–vis spectra of the reduction process undergone by Ag1ions in the absence of Idrocap994.346COCCA AND D’ORAZIOJournal of Polymer Science:Part B:Polymer PhysicsDOI10.1002/polb多变形的groups in both the plain poly(carbonate ure-thane)and the silver/poly(carbonate urethane)nanocomposite are involved in hydrogen bond-ing.The carbonyl-stretching band in the 1800–1600cm À1region was overlapped by fourstretching bands at $1743,$1730,$1720,and $1700cm À1because of the absorption of the free carbonyl of soft segments,free carbonyl of urethane,hydrogen-bonded carbonyl in car-bonate,and hydrogen-bonded carbonyl of ure-thane,respectively.In Figure 5,the peak separation of the IR carbonyl bands by peakdeconvolution (per-formed by means of a deconvolution process and Gaussian fitting by Thermogalactic Grams/AI 7.01software)is shown for poly(carbonate ure-thane)and silver nanocomposite.A linear base-line from 1800to 1600was chosen for the decon-volution of C ¼¼O region.The deconvolution data of the carbonyl peaks are reported in Table 1.Hence,the ratio of area under the peaks ofhydrogen-bonded carbonyl (A HCO )and free car-bonyl groups (A FCO )of urethane and the ratio of area under hydrogen-bonded carbonyl and free carbonyl groups of carbonate were calcu-lated.25,26The area ratio average value between hydrogen bonded and free carbonyl (A HCO /A FCO )of urethane in the nanocomposite was found to be lesser (0.48)than that shown by the plain poly(carbonate urethane)(0.57).Also,the area ratio between hydrogen bonded and free car-bonyl (A HCO /A FCO )of carbonate decreases to 0.86from 0.89calculated for the plain poly(car-bonate urethane).Such results indicate that the presence of silver nanoparticles causes a reduc-tion in both hydrogen-bonded carbonyl adsorp-tion of urethane and carbonyl adsorption of car-bonate,the extent of the observed decrease being larger for hydrogen-bonded carbonyl of urethane groups.Therefore,the silver nanoparticles are found to strongly modify poly(carbonate urethane)morphology through a decrease in its phase sep-aration,that is,an increase in its phase mixing.Moreover,the areas under the peaks of ÀÀNH(A NH )and ÀÀCH (A CH )2860–2940cm À1have been calculated;the A CH was used as an inter-Scheme 1.Schematic summarizing the steps leading to the formation of silver nanoparticles in a polyurethane matrix.Figure 3.SEM micrograph showing the morphologi-cal features of silver/Idrocap 994nanocomposite.Figure 4.ATR-FTIR spectra of (A)Idrocap 994and (B)silver/Idrocap 994nanocomposite.NOVEL SILVER/POLYURETHANE NANOCOMPOSITE347Journal of Polymer Science:Part B:Polymer Physics DOI 10.1002/polb重叠的nal standard,and the ratio between A NH and A CH was determined.24For silver/poly(urethane carbonate),the ratio A NH /A CH decreases to 1.15from 1.19average value shown by plain poly (carbonate urethane),further confirming that the hydrogen bonding between ÀÀNH and carbonyls (whether they are in hard or soft segments)was hindered by the presence of silver nanoparticles.DMTA TestsThe loss factor tan d at 1Hz for plain poly(car-bonate urethane)and the nanocomposite sam-ples is shown in Figure6.The tan d plots reveal the occurrence of one a -relaxation process corre-sponding to the glass transition of soft segment in both plain poly(carbonate urethane)and sil-ver nanocomposite.From the data in Figure 6,with respect to the dispersion of silver nano-phase within the poly(carbonate urethane)Table 1.FTIR-Deconvolution Analysis of Poly (carbonate urethane)and Silver NanocompositeCenterArea Plain poly(carbonate urethane)17420.76917130.96016770.68616430.556Silver/poly(carbonate urethane)nanocomposite17410.8291718 1.20916920.71716520.584Figure 6.Tan d as a function of temperature for Idrocap 994and silver/Idrocap 994nanocomposite.Figure 5.ATR-FTIR spectra and relative curve-fit-ting analysis in the region 1800–1600cm À1for (A)Idrocap 994and (B)silver/Idrocap 994nanocomposite.Figure 7.Tan d as a function of temperature col-lected at nine different frequencies for (A)Idrocap 994and (B)silver/Idrocap 994nanocomposite.348COCCA AND D’ORAZIOJournal of Polymer Science:Part B:Polymer PhysicsDOI 10.1002/polbmatrix,no displacement of the nanocomposite a peak can be clearly detected;such afinding could be ascribed to the broadness of the a-tran-sitions.Both the resulting materials are charac-terized by a T g value of approximatelyÀ228C. Therefore,a multifrequency analysis was car-ried out to gather details on the effect of the sil-ver nanophase.Figure7(B)shows the tan d versus tempera-ture curves collected at nine different frequen-cies on the nanocomposite sample.Note that,by increasing the frequency,the peak maxima shift at higher temperatures while the intensities decrease.A similar behavior was observed for the plain poly(carbonate urethane),see Figure 7(A).The characteristic time for local segmental relaxation was calculated by the frequency cor-responding to the loss function peak s¼1/f.The temperature dependence was examined using the Arrhenius equation expressed as:ln s¼ln s0ÀE a RTwhere s is the relaxation time for the peak,s0is a constant,E a is the activation energy,R is the gas constant,and T is the absolute peak temper-ature.In Figure8,the logarithm of s is plotted versus1/T relative to the a-relaxation process.The activation energies for plain poly(carbon-ate urethane)and silver nanocomposite deter-mined from the slope of the Arrhenius plots are 280.3and334.6kJ/mol,respectively.Thus,the E a value shown by the plain poly(carbonate ure-thane)is lower than that exhibited by the nano-composite indicating that the molecular motions of poly(carbonate urethane)soft segments are restricted by the presence of the silver nanocrys-tals,as higher energy is required for relaxation.Such results could suggest a molecular scale contiguity between the silver nanophase and polyurethane soft segments. CONCLUSIONSA novel silver/poly(carbonate urethane)nanocom-posite was achieved through in situ chemical reduction of silver ions carried out in the pres-ence of a commercial poly(carbonate urethane) dissolved in DMF.The reduction process of silver ions was monitored by UV–vis spectra and was found to be assisted by poly(carbonate urethane)presence preventing the aggregation phenomena.FESEM investigation showed,as a matter of fact, that silver nanoprisms(mainly triangular and polygonal)are homogeneously dispersed in the poly(carbonate urethane)matrix after DMF cast-ing.FTIR analysis of the areas underÀÀNH and carbonyl peaks highlighted that the presence of silver nanoparticles strongly modifies the poly (carbonate urethane)morphology.Hydrogen bond-ing between carbonyl and NH groups of hard seg-ment resulted,in fact,hindered thus inducing a decrease in phase separation.Multifrequency DMTA analysis showed moreover that the silver nanophase presence affects the T g relaxation pro-cess of the poly(carbonate urethane)soft segment.An increased activation energy is required for relaxation in the presence of the nanophase.The reduced tendency of the polyurethane chains to-ward self-association through molecular intercon-nections of the hydrogen bonding type and the increase in activation energy were attributed to the molecular scale proximity between the dis-persed nanophase and matrix.The authors are thankful for the support of the CRdC INNOVA for FESEM and FTIR investigations.REFERENCES AND NOTES1.Gittins,D.I.;Bethell,D.;Schiffrin,D.J.;Nichols,R.J.Nature2000,408,67–69.2.Ghosh,K.;Maiti,S.N.J Appl Poly Sci1996,60,323–331.3.Shanmugam,S.;Viswanathan, B.;Varadarajan,T.K.Mater Chem Phys2006,95,51–55.4.Remita,S.;Mostafavi,M.;Delcourt,M.O.RadiatPhys Chem1996,47,275–279.Figure8.Arrhenius plot relative to the a-transition for Idrocap994and silver/Idrocap994nanocomposite. 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