Accelerated brush growth on nanoparticle surfaces by reversible addition‐fragmentation chain transfer polymerization

Jiao, Yang; Akcora, Pinar

doi:10.1002/pola.27170

Cited by 12 publications

(28 citation statements)

References 42 publications

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“…A comparison of the SEC data of degrafted and free PHMA polymers (Figures 2b and S10b, Table 1) shows that the molecular weight of the free polymers is lower than tethered polymer chains. Other authors have also reported longer chains for the grafts than for free polymers, 39,42 and as above mentioned the effect appears to be a consequence of the reduced mobility of the tethered propagating chains, which in turn limits chain termination. The slight broadening of the molecular weight distributions observed for the PMMA synthesized via surface-initiated polymerization is in good agreement with the behavior predicted by Turgman-Cohen and Genzer, i.e.…”

Section: Resultsmentioning

confidence: 66%

One-Component Nanocomposites Based on Polymer-Grafted Cellulose Nanocrystals

et al. 2020

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Cellulose nanocrystals (CNCs) are widely used as reinforcing filler in polymers, due to their exceptionally high stiffness and strength and because the biological species from which they are isolated represent renewable resources. However, aggregation of the CNCs, which is concomitant with limited reinforcement, is often difficult to avoid. One-component nanocomposites (OCNs) based on polymer-grafted nanoparticles can solve this problem, because this approach affords, by design, materials in which no such aggregation is possible.At the same time, chain entanglements between the CNC-grafted polymer chains provide stress-transfer among the particles. To demonstrate this, we investigated OCNs based on polymethacrylate-grafted CNCs. A previously un-accessed compositional space, i.e., OCNs with a CNC content of 10 or 20 wt%, was explored. Cotton linter-based CNCs were modified via surface-photoinitiated free radical polymerization, which involved the functionalization of the CNC surfaces with benzophenone moieties as photo-radical initiator species, and the subsequent surface-photoinitiated polymerization of methyl or hexyl methacrylate under UVirradiation at 365 nm. The resulting particles readily dispersed in THF. Solvent-casting and compression-molding afforded films of homogeneous appearance, which display remarkable 2 improvements in stiffness or toughness and strength in comparison to conventional twocomponent nanocomposites of unmodified CNCs and the respective polymers.Polymer-grafted CNCs can be synthesized via "grafting-from", "grafting-to", or "graftingthrough" approaches involving functional groups on the CNCs surface. 3,32 The grafting-from approach, which was utilized here, involves the functionalization of the CNCs with polymer brushes by way of surface-initiated polymerization from initiator groups immobilized on the NPs' surface. This framework generally leads to polymer grafts with a well-controlled length and high polymer grafting density. 3 The first example of OCNs based on polymer-grafted CNCs, using a grafting-from approach, was reported by Chen et al., 7 who functionalized CNCs with semicrystalline poly(ε-caprolactone) via surface-initiated ring-opening polymerization.OCNs with a CNC content of between 4 and 8 wt% proved to be melt-processable and the authors reported a non-linear dependence between the CNC content and the OCN mechanical properties. Unfortunately, no comparison with conventional composites was made and no correlation between the PCL graft structure and the properties of the OCNs could be established. In another study, Chang et al. reported the synthesis of CNCs-g-poly(ethynylenefluorene) through Sonogashira coupling via a grafting-from approach, 8 but the mechanical properties of the material were not investigated.Here, we report the synthesis of amorphous, polymethacrylate-grafted CNCs through a synthetically undemanding free radical polymerization protocol. It involves the surface functionalization of CNCs with a benzophenone derivative that serves as radical photoinitiator f...

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Section: Resultsmentioning

confidence: 66%

One-Component Nanocomposites Based on Polymer-Grafted Cellulose Nanocrystals

et al. 2020

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“…PGNs with canopy dominated by SDPB conformations ( r c ⩽ r 0 ) were synthesized via surface-initiated reversible addition–fragmentation chain transfer (RAFT) polymerization of polystyrene (PS) from iron oxide nanoparticles ( r 0 = 3.85 ± 0.55 nm) . In brief, iron oxide nanoparticles were first synthesized and stabilized with oleic acid and oleylamine.…”

Section: Resultsmentioning

confidence: 99%

“…Oleic acid and oleylamine-stabilized Fe 3 O 4 nanoparticles were synthesized by the high-temperature thermal decomposition method . Fe 3 O 4 –PS PGNs were synthesized by surface-initiated reversible addition–fragmentation chain transfer (RAFT) polymerization based on previously published protocols with the same materials used . To remove free chains, the product was washed multiple times by suspending in toluene followed by pelletization.…”

Section: Experimental Sectionmentioning

confidence: 99%

Deformation Behavior of Polystyrene-Grafted Nanoparticle Assemblies with Low Grafting Density

et al. 2018

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Matrix-free, polymer-grafted nanoparticle (PGN) assemblies show promise for a wide array of structural, photonic, and electrical applications. We examine the modulus, yield strength, and crazing of assemblies of polystyrene grafted Fe 3 O 4 (Fe 3 O 4 -PS) at low graft density (Σ < 0.15 chains/nm 2 ) where chain entanglements are maximized. From the wrinkling−cracking method (WCM) we show that modulus (E) and yield stress (σ y ) are independent of nanoscale film thickness (70 < h f < 250 nm) and graft molecular weight (30 kDa < MW < 370 kDa) and in good agreement with predictions from effective medium theory. Furthermore, thin film craze observations from TEM imply two critical length scales for maximum deformability of matrix-free PGN assemblies: (1) PGN core size should be less than the critical length scale of the craze microstructure, and (2) near-neighbor entanglements are optimized for the lowest graft length (N) where the PGN architecture exhibit intermediate graft densities (r 0 Σ 0.5 ∼ 3−6 and N/N e ∼ 4−6). These findings provide a foundation for optimizing designs that simultaneously maximize inorganic volume fraction, processability, and mechanical robustness for PGN thin film assemblies.

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“…Jiao et al [ 96 ] demonstrated the importance of CTA coverage on the kinetics of RAFT polymerization. In this study, the polymerization of styrene with CTA-functionalized Fe 3 O 4 NPs in the presence of free CTAs was performed.…”

Section: Core-brush Nanoparticlesmentioning

confidence: 99%

Design, Synthesis and Architectures of Hybrid Nanomaterials for Therapy and Diagnosis Applications

2018

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Hybrid nanomaterials based on inorganic nanoparticles and polymers are highly interesting structures since they combine synergistically the advantageous physical-chemical properties of both inorganic and polymeric components, providing superior functionality to the final material. These unique properties motivate the intensive study of these materials from a multidisciplinary view with the aim of finding novel applications in technological and biomedical fields. Choosing a specific synthetic methodology that allows for control over the surface composition and its architecture, enables not only the examination of the structure/property relationships, but, more importantly, the design of more efficient nanodevices for therapy and diagnosis in nanomedicine. The current review categorizes hybrid nanomaterials into three types of architectures: core-brush, hybrid nanogels, and core-shell. We focus on the analysis of the synthetic approaches that lead to the formation of each type of architecture. Furthermore, most recent advances in therapy and diagnosis applications and some inherent challenges of these materials are herein reviewed.

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Accelerated brush growth on nanoparticle surfaces by reversible addition‐fragmentation chain transfer polymerization

Cited by 12 publications

References 42 publications

One-Component Nanocomposites Based on Polymer-Grafted Cellulose Nanocrystals

One-Component Nanocomposites Based on Polymer-Grafted Cellulose Nanocrystals

Deformation Behavior of Polystyrene-Grafted Nanoparticle Assemblies with Low Grafting Density

Design, Synthesis and Architectures of Hybrid Nanomaterials for Therapy and Diagnosis Applications

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