Synthesis of Polystyrene-Grafted Polyorganosiloxane Microgels and Their Compatibility with Linear Polystyrene Chains

Lindenblatt, Gudrun; Schärtl, Wolfgang; Pakuła, Tadeusz; Schmidt, Manfred

doi:10.1021/ma001328f

Cited by 59 publications

(82 citation statements)

References 23 publications

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“…A common strategy to suppress aggregation is a functionalization by grafting polymer chains on the nanoparticles, typically using a polymer chemically identical to the matrix chains. 7,8 Characteristics of the particles, such as the length and surface density of the grafted chains, not only influence the particle-polymer compatibility, but also affect the interparticle interactions and thereby the dynamical behavior of the whole system. 8,9 An issue of fundamental importance, which has not been addressed previously in simulations, is the dynamical behavior of grafted nanoparticles in the absence of free chains or solvent.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of solvent-free grafted nanoparticles

Chremos

Panagiotopoulos

Koch

2012

The Journal of Chemical Physics

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The diffusivity and structural relaxation characteristics of oligomer-grafted nanoparticles have been investigated with simulations of a previously proposed coarse-grained model at atmospheric pressure. Solvent-free, polymer-grafted nanoparticles as well as grafted nanoparticles in a melt were compared to a reference system of bare (ungrafted) particles in a melt. Whereas longer chains lead to a larger hydrodynamic radius and lower relative diffusivity for grafted particles in a melt, bulk solvent-free nanoparticles with longer chains have higher relative diffusivities than their short chain counterparts. Solvent-free nanoparticles with short chains undergo a glass transition as indicated by a vanishing diffusivity, diverging structural relaxation time and the formation of body-centered-cubic-like order. Nanoparticles with longer chains exhibit a more gradual increase in the structural relaxation time with decreasing temperature and concomitantly increasing particle volume fraction. The diffusivity of the long chain nanoparticles exhibits a minimum at an intermediate temperature and volume fraction where the polymer brushes of neighboring particles overlap, but must stretch to fill the interparticle space.

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Section: Introductionmentioning

confidence: 99%

Dynamics of solvent-free grafted nanoparticles

Chremos

Panagiotopoulos

Koch

2012

The Journal of Chemical Physics

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“…A strong impact on scientific activities has been caused by the famous investigation of Toyota Motor Co. which involved the reinforcement of polyamide with nanoclay 2. Still from the early days up to day a great challenge in the research field of polymeric nanocomposites is the achievement of a uniform dispersion of the filler material in the polymer matrix in order to achieve optimum properties 3–5. In the case of inorganic fillers like silica a uniform dispersion is difficult to achieve because agglomeration in organic matrices is highly favored 6.…”

Section: Introductionmentioning

confidence: 99%

Modification of Polycarbonate and Glycol Modified Poly(ethylene terephthalate) by Addition of Silica‐Nanoparticles Grafted with SAN Copolymer Using “Classical” and ARGET ATRP

Haase¹,

Hesse²,

Brommer³

et al. 2012

Macro Materials & Eng

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This study presents a nanocomposite manufacturing route starting from non‐functionalized nanosilica and SAN surface modification via “grafting from” ATRP up to processing of transparent polycarbonate and glycol modified poly(ethylene terephthalate) nanocomposites. Synthesis limitations of low molecular weight graft SAN derived from “classical” ATRP are overcome by employment of the emerging ARGET ATRP. Mechanical investigations of polycarbonate and glycol modified poly(ethylene terephthalate) nanocomposites present up to 80% enhancement of creep performance and additionally 70% enhancement against wear abrasion for glycol modified poly(ethylene terephthalate) nanocomposites. Strength and tensile modulus are only moderately influenced by the addition of nanoparticles. Morphological studies confirm that the present modification route is able to create uniform dispersions of single particles and small particle aggregates in polymer matrices.

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“…However, chemical matching is not the only factor controlling the compatibility of the polymergrafted NPs in the polymer matrix [29]. The dispersion of polymergrafted NPs in a homopolymer matrix also depends on other parameters including the molecular weight of polymer brush (M), the molecular weight of the matrix (P), and the grafting density of the brush [30][31][32][33][34][35][36][37][38]. For example, if the polymer brush is swollen or wet by the matrix chains, dispersion of the NPs will be favored [10,39,40].…”

Section: Introductionmentioning

confidence: 99%

Dispersion of polymer-grafted magnetic nanoparticles in homopolymers and block copolymers

Ohno

Ladmiral

et al. 2008

Polymer

157

145

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The dispersion of magnetic nanoparticles (NPs) in homopolymer poly(methyl methacrylate) (PMMA) and block copolymer poly(styrene-b-methyl methacrylate) (PS-b-PMMA) films is investigated by TEM and AFM. The magnetite (Fe 3 O 4 ) NPs are grafted with PMMA brushes with molecular weights from M = 2.7 to 35.7 kg/mol. Whereas a uniform dispersion of NPs with the longest brush is obtained in a PMMA matrix (P = 37 and 77 kg/mol), NPs with shorter brushes are found to aggregate. This behavior is attributed to wet and dry brush theory, respectively. Upon mixing NPs with the shortest brush in PS-b-PMMA, as-cast and annealed films show a uniform dispersion at 1 wt%. However, at 10 wt%, PS-b-PMMA remains disordered upon annealing and the NPs aggregate into 22 nm domains, which is greater than the domain size of the PMMA lamellae, 18 nm. For the longest brush length, the NPs aggregate into domains that are much larger than the lamellae and are encapsulated by PS-b-PMMA which form an onion-ring morphology. Using a multicomponent Flory-Huggins theory, the concentrations at which the NPs are expected to phase separate in solution are calculated and found to be in good agreement with experimental observations of aggregation. The dispersion of magnetic nanoparticles (NPs) in homopolymer poly(methyl methacrylate) (PMMA) and block copolymer poly(styrene-b-methyl methacrylate) (PS-b-PMMA) films is investigated by TEM and AFM. The magnetite (Fe 3 O 4 ) NPs are grafted with PMMA brushes with molecular weights from M ¼ 2.7 to 35.7 kg/mol. Whereas a uniform dispersion of NPs with the longest brush is obtained in a PMMA matrix (P ¼ 37 and 77 kg/mol), NPs with shorter brushes are found to aggregate. This behavior is attributed to wet and dry brush theory, respectively. Upon mixing NPs with the shortest brush in PS-b-PMMA, as-cast and annealed films show a uniform dispersion at 1 wt%. However, at 10 wt%, PS-b-PMMA remains disordered upon annealing and the NPs aggregate into 22 nm domains, which is greater than the domain size of the PMMA lamellae, 18 nm. For the longest brush length, the NPs aggregate into domains that are much larger than the lamellae and are encapsulated by PS-b-PMMA which form an onion-ring morphology. Using a multi-component Flory-Huggins theory, the concentrations at which the NPs are expected to phase separate in solution are calculated and found to be in good agreement with experimental observations of aggregation.

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Synthesis of Polystyrene-Grafted Polyorganosiloxane Microgels and Their Compatibility with Linear Polystyrene Chains

Cited by 59 publications

References 23 publications

Dynamics of solvent-free grafted nanoparticles

Dynamics of solvent-free grafted nanoparticles

Modification of Polycarbonate and Glycol Modified Poly(ethylene terephthalate) by Addition of Silica‐Nanoparticles Grafted with SAN Copolymer Using “Classical” and ARGET ATRP

Dispersion of polymer-grafted magnetic nanoparticles in homopolymers and block copolymers

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