基于Diels-Alder反应的热可逆高导电硅橡胶/碳管复合材料的制备
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摘要
使用碳纳米管(CNTs)作为亲二烯体,制备了接枝呋喃官能团的硅橡胶(SiR-Fu)作为二烯体,二者进行Diels-Alder反应,在CNTs与SiR-Fu基体之间构建了可逆共价交联网络,制备了一种同时具有良好的界面粘结、较好的力学强度、高导电性和较好热可逆性质的导电硅橡胶(SiR)复合材料.其中,CNTs既作为增强填料和导电填料,又能与SiR主链上的呋喃官能团发生Diels-Alder反应而形成动态共价键,使得复合材料具有热可逆性、可回收再利用性且能提高复合材料的界面粘结和力学强度.较之纯SiR,CNTs含量为10 wt%的复合材料的电导率从2.5×10~(-14) S/cm提高到0.9 S/cm;拉伸强度从0.2 MPa提高到2.3 MPa;对样品进行二次模压成型之后,其拉伸强度回复率为77%,断裂伸长率回复率为88%,电导率回复率为86%.
An emerging and crucial type of high-value-added functional materials, conductive elastomer composites(CEC) have found extensive applications in the fields of military and civil electromagnetic shielding/protection by virtue of their excellent electromagnetic shielding function and environmental sealing performance. However, practical uses of CEC materials can be largely compromised by such disadvantages as difficult rubber recovery, poor interfacial adhesion, and costly conductive fillers. In this study, methyl vinyl silicone rubber(SiR) with high vinyl content(20%, 30% and 50%) was firstly synthesized through an anionic ring-opening reaction, and as-prepared SiR was grafted with furan functional groups via the thiol-ene click chemical reaction to afford furan-grafted SiR(SiR-Fu). SiR-Fu/CNTs composites were then prepared by solution blending of SiR-Fu and carbon nanotubes(CNTs), during which Diels-Alder reaction occurred with SiR-Fu as the diene and CNTs as the dienophiles, giving rise to reversible covalent cross-linking networks throughout the resulting composites. SEM images showed that diameters of most CNTs in SiR-Fu/5 wt% CNTs and SiR-Fu/10 wt%CNTs composites were significantly larger than those of the raw CNTs due to a SiR layer coated on the nanotube surface, indication of the DA reaction between CNTs and SiR-Fu. However, CNTs tended to agglomerate when being further increased to 20 wt% and some of them showed little change in diameter as compared with the initial values, so that no DA reaction took place in that case. In addition, the gel content of SiR-Fu/5 wt% CNTs and SiRFu/10 wt% CNTs composites was 73% and 90%, respectively, suggesting an enhanced degree of DA reaction at increasing CNTs content within a certain range, while it decreased to 24.5% at 20 wt% CNTs addition for the reduced degree of DA reaction caused by CNTs agglomeration. Therefore, composites with 5 wt% and 10 wt%CNTs showed better interfacial adhesion, higher mechanical strength, greater electrical conductivity, and favorable thermal reversibility. Particularly, the electrical conductivity and tensile strength of SiR-Fu/10 wt%CNTs composite reached 0.9 S/cm and 2.3 MPa, respectively, much improved than those of the neat SiR(2.5 ×10~(-14) S/cm and 0.2 MPa). Moreover, the initial tensile strength, elongation at break, and electrical conductivity could be retained at 77%, 88%, and 86%, respectively, after composite reprocessing.
An emerging and crucial type of high-value-added functional materials, conductive elastomer composites(CEC) have found extensive applications in the fields of military and civil electromagnetic shielding/protection by virtue of their excellent electromagnetic shielding function and environmental sealing performance. However, practical uses of CEC materials can be largely compromised by such disadvantages as difficult rubber recovery, poor interfacial adhesion, and costly conductive fillers. In this study, methyl vinyl silicone rubber(SiR) with high vinyl content(20%, 30% and 50%) was firstly synthesized through an anionic ring-opening reaction, and as-prepared SiR was grafted with furan functional groups via the thiol-ene click chemical reaction to afford furan-grafted SiR(SiR-Fu). SiR-Fu/CNTs composites were then prepared by solution blending of SiR-Fu and carbon nanotubes(CNTs), during which Diels-Alder reaction occurred with SiR-Fu as the diene and CNTs as the dienophiles, giving rise to reversible covalent cross-linking networks throughout the resulting composites. SEM images showed that diameters of most CNTs in SiR-Fu/5 wt% CNTs and SiR-Fu/10 wt%CNTs composites were significantly larger than those of the raw CNTs due to a SiR layer coated on the nanotube surface, indication of the DA reaction between CNTs and SiR-Fu. However, CNTs tended to agglomerate when being further increased to 20 wt% and some of them showed little change in diameter as compared with the initial values, so that no DA reaction took place in that case. In addition, the gel content of SiR-Fu/5 wt% CNTs and SiRFu/10 wt% CNTs composites was 73% and 90%, respectively, suggesting an enhanced degree of DA reaction at increasing CNTs content within a certain range, while it decreased to 24.5% at 20 wt% CNTs addition for the reduced degree of DA reaction caused by CNTs agglomeration. Therefore, composites with 5 wt% and 10 wt%CNTs showed better interfacial adhesion, higher mechanical strength, greater electrical conductivity, and favorable thermal reversibility. Particularly, the electrical conductivity and tensile strength of SiR-Fu/10 wt%CNTs composite reached 0.9 S/cm and 2.3 MPa, respectively, much improved than those of the neat SiR(2.5 ×10~(-14) S/cm and 0.2 MPa). Moreover, the initial tensile strength, elongation at break, and electrical conductivity could be retained at 77%, 88%, and 86%, respectively, after composite reprocessing.
引文
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2 Choong C L,Shim M B,Lee B S,Jeon S,Ko D S,Kang T H,Bae J,Lee S H,Byun K E,Im J,Jeong Y J,Park C E,Park J J,Chung U I.Adv Mater,2014,26(21):3451-3458
3 Polgar L M,van Duin M,Broekhuis A A,Picchioni F.Macromolecules,2015,48(19):7096-7105
4 Polgar L,Hagting E,Koek W J,Picchioni F,van Duin M.Polymers,2017,9(3):81
5 Zhang H,Cai C,Liu W,Li D D,Zhang J W,Zhao N,Xu J.Sci Rep,2017,7(1):11833
6 Zhang B L,Zhang P,Zhang H Z,Y an,Casey Y,Zheng Z J,Wu B,Yu,Y.Macromol Rapid Commun,2017,38(15):1700110
7 Amamoto Y,Kikuchi M,Masunaga H,Sasaki S,Otsuka H,Takahara A.Macromolecules,2010,43(4):1785-1791
8 Zhao Hanwen(赵翰文),Feng Libang(冯利邦),Shi Xueting(史雪婷),Wang Yanping(王彦平).Acta Polymerica Sinica(高分子学报),2018,(3):395-401
9 Diels O,Alder K.Justus Liebigs Ann Chem,1928,460(1):98-122
10 Polgar M L,Hagting E,Raffa P,Mauri M,Simonutti R,Picchioni F,Duin M.Macromolecules,2017,50(22):8955-8964
11 Trovatti E,Lacerda T M,Carvalho A J,Gandini A.Adv Mater,2015,27(13):2242-2245
12 Zhao J,Xu R,Luo G X,Wu J,Xia H S.J Mater Chem B,2016,4(5):982-989
13 Xiang Hongping(向洪平),Rong Zhimin(容敏智),Zhang Mingqiu(章明秋).Acta Polymerica Sinica(高分子学报),2017,(7):1130-1140
14 Roy S,Das T,Zhang L,Li Y,Ming Y,Ting S,Hu X,Yue C Y.Polymer,2015,58:153-161
15 Xue S M,Xu Z L,Tang Y J,Ji C H.ACS Appl Mater Interfaces,2016,8(29):19135-44
16 Dumitru A,Mamlouk M,Scott K.Electrochi Acta,2014,135:428-438
17 Miller S G,Williams T S,Baker J S,Sola F,Lebron-Colon M,McCorkle L S,Wilmoth N G,Gaier J,Chen M,Meador M A.ACS Appl Mater Interfaces,2014,6(9):6120-6126
18 Araya-Hermosilla R,Pucci A,Raffa P,Santosa D,Pescarmona P P,Gengler N Y R,Rudolf P,Moreno-Villoslada I,Picchioni F.Polymers,2018,10(10):1076
19 Li Y,Osuna S,Garcia-Borras M,Qi X,Liu S,Houk K N,Lan Y.Chem Eur J,2016,22(36):12819-24
20 Mata D,Amaral M,Fernandes A J,Colaco B,Gama A,Paiva M C,Gomes P S,Silva R F,Fernandes M H.Nanoscale,2015,7(20):9238-9251
21 Willocq B,Lemaur V,Garah E M,Ciesielski A,Samori P,Raquez J M,Dubois P,Cornil J.Chem Commun,2016,52(48):7608-7611
22 Willocq B,Bose R K,Khelifa F,Garcia S J,Dubois P,Raquez J M.J Mater Chem A,2016,4(11):4089-4097
23 Zhang W,Zhou Z,Li Q,Chen G X.Ind Eng Chem Res,2014,53(16):6699-6707
24 Lowe A B.Polym Chem,2010,1(1):17-36
25 Schenzel A M,Klein C,Rist K,Moszner N,Barner-Kowollik C.Adv Sci,2016,3(3):1500361
26 Inglis A J,Sinnwell S,Stenzel M H,Barner-Kowollik C.Angew Chem Int Ed,2009,48(13):2411-2414
27 Gacal B,Durmaz H,Tasdelen M A,Hizal G,Tunca U,Yagci Y,Demirel A L.Macromolecules,2006,39(16):5330-5336
28 Xiong X Q,Chen Y M.Eur Polym J,2012,48(3):569-579
29 Xiong X Q,Xu Y H.Polym Bull,2010,65(5):455-463
30 Durmaz H,Colakoglu B,Tunca U,Gurkan H.J Polym Sci,Part A:Polym Chem,2006,44(5):1667-1675
31 Yusuke I,Hideaki I,Kensuke N,Yoshiki C.Macromolecules,2000,33(12):4343-4346
32 Chen X,Dam M A,Ono K,Ajit M,Hongbin S,Steven R N,Kevin S,Fred W.Science,2002,295(5560):1698-1702
33 Chen X X,Fred W,Ajit K M,Shen H B,Steven R N.Macromolecules,2003,36(6):1082-1807
34 Michael L S,Dominic V M,David R W,Thomas Z,James R M.Macromolecules,2007,40(4):818-823