期刊
ADVANCED MATERIALS INTERFACES
卷 5, 期 18, 页码 -出版社
WILEY
DOI: 10.1002/admi.201800511
关键词
dynamic covalent chemistry (DCC); interfacial stress relaxation; nanocomposites; reversible addition fragmentation chain transfer (RAFT); silica nanoparticles (SNP)
资金
- National Science Foundation (NSF) [DMR 1310528]
- National Institutes of Health (NIH) [1U01DE023777]
- NATIONAL INSTITUTE OF DENTAL & CRANIOFACIAL RESEARCH [U01DE023777] Funding Source: NIH RePORTER
- Division Of Materials Research [1310528] Funding Source: National Science Foundation
The interfacial region in composites that incorporate filler materials of dramatically different modulus relative to the resin phase acts as a stress concentrator and becomes a primary locus for composite failure. A novel adaptive interface (AI) platform formed by coupling moieties capable of dynamic covalent chemistry (DCC) is introduced to the resin-filler interface to promote stress relaxation. Specifically, silica nanoparticles (SNP) are functionalized with a silane capable of addition fragmentation chain transfer (AFT), a process by which DCC-active bonds are reversibly exchanged upon light exposure and concomitant radical generation, and copolymerized with a thiol-ene resin. At a fixed SNP loading of 25 wt%, the toughness (2.3 MJ m(-3)) is more than doubled and polymerization shrinkage stress (0.4 MPa) is cut in half in the AI composite relative to otherwise identical composites that possess a passive interface (PI) with similar silane structure, but without the AFT moiety. In situ activation of the AI during mechanical loading results in 70% stress relaxation and three times higher fracture toughness than the PI control. When interfacial DCC was combined with resin-based DCC, the toughness was improved by 10 times relative to the composite without DCC in either the resin or at the resin-filler interface.
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