低介电常数的介孔SiO_2/PMMA杂化材料的研究

Study of novel low-κ mesoporous silica/PMMA hybrid materials

为降低PMMA的介电常数,同时提高其力学性能和热性能,利用原位分散聚合法以二维六方孔结构SiO2(SBA-15)和蠕虫状孔结构SiO2(MSU-J)为填料制备了PMMA杂化材料.采用XRD、FT-IR、SEM、TEM和DSC等方法研究了杂化材料的微观形貌特征、介电常数、力学性能和热性能.结果表明:含质量分数7%有机化修饰的SBA-15或MSU-J的PMMA杂化材料介电常数由2.91分别降至2.68和2.56;且在较宽范围频率下杂化材料的介电常数稳定.这主要是由于介孔孔道储存空气(κ=1)、界面间隙及大的粒径带来的自由体积的引入降低了杂化材料的介电常数,同时也使杂化材料的力学性能和热性能得到显著提高.

To reduce the dielectric constant of PMMA, and improve the mechanical and thermal properties, mesoporous silica/PMMA hybrid materials containing dimensional hexagonal structure （SBA - 15 ） or Wormhole structure （MSU-J） type mesoporous silica were successfully prepared via in situ polymerization. Their morphologies, dielectric constants, and thermal and mechanical properties were investigated by XRD, FI-IR, SEM, TEM and DSC. The conclusions reveal that the dielectric constants of hybrid materials can be reduced from 2. 91 of pure PMMA to 2. 68 and 2. 56 containing 7wt% modified SBA - 15 or modified MSU-J, respectively. And the mesoporous silica/PMMA also present stable~ dielectric constants across the wide frequency rang. The reduction of the dielectric constant is attributed to the incorporation of the air voids （K = 1 ） stored within the mesoporous silica, the air volume existing in !he gaps between the mesoporous silica and PMMA matrix, and the free volume created by introducing large-sized domains. Moreover, the mechanical and thermal performance of hybrid material are dramatically improved.