Features of styrene polymerization initiated by peroxide initiators grafted on the aerosil filler surface

Ivanchev, S. S.; Yenikolopyan, N.S.; Polozov, B. V.; Dimtrenko, A.V.; Demidova, V.A.; Krupnik, A.M.; Litkovets, A.K.

doi:10.1016/0032-3950(81)90250-1

Cited by 5 publications

(4 citation statements)

References 2 publications

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“…The amount of grafted polymer does not exceed approximately 2−10 mg/m 2 . It was reported that a big amount of polymer can be grafted on the surface using polymerization from the substrate. ,− The most common way of the “ grafting from ” process includes the introduction of an initiator for radical polymerization into a substrate surface usually using silane chemistry where a dense monolayer of initiator on metal or silicon oxide surfaces can be formed . In the next step the grafting of vinyl monomer is performed from solution or gas phase.…”

Section: Introductionmentioning

confidence: 99%

Switching of Polymer Brushes

et al. 1999

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Polymer coatings of brushlike monolayers composed of two different polymers, polystyrene and poly(2-vinylpyridine), are grafted by radical polymerization on the surface of silicon wafers. Thickness, grafting density, molecular weight of grafted chains, and the composition of the coatings were regulated by grafting time, monomer concentration, and additional initiator in solution. A typical dry film thickness is between 10 and 100 nm, and the molecular weights of the components range from 100 to 300 kg/mol. The fabricated coatings turn out to be sensitive to the composition of the environment. For instance after exposition to toluene the layer becomes hydrophobic and the top of the layer is covered by polystyrene. After exposition to HCl the layer becomes hydrophilic with polyvinylpyridine in the upper layer. This reconstruction of the polymer layer was observed with contact angle and X-ray photoelectron spectroscopy measurements. The composition of the top layer in different media is controlled by the composition and molecular weight of the two polymers in the coating. The “switching” properties of the coating are shown to be reversible.

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Section: Introductionmentioning

confidence: 99%

Switching of Polymer Brushes

et al. 1999

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“…It is known from the published data ,− , that in most cases the grafted amount reaches a plateau value which is on the order of the polymer adsorption value (1−2 mg/m 2 ). However, in some cases, it was found that the grafting amount could be on the order of 50−100 mg/m 2 .…”

Section: Brief Review Of the Literature Datamentioning

confidence: 99%

“…A common picture of the grafting polymerization on the solid surface emerges from the literature. Its features are the following: (a) At a relatively short time after the start of the process, the grafting amount approaches a plateau value; , however, especially for methacrylates, the acceleration of grafting (like the Trommsdorff effect) has been observed. ,,,, (b) A pronounced dependence on monomer concentration occurs. ,− (the grafting rate order in monomer concentration is very often larger than 1). (c) A low efficiency (0.01−0.45) of the initiation reaction is noted. ,, (d) The polymerization rate order on the initiator concentration is 0.5−1 (often it is higher than 0.5). − ,,, (e) Very often, the grafted polymer layer is composed of partially cross-linked polymer .…”

Section: Brief Review Of the Literature Datamentioning

confidence: 99%

Radical Polymerization Initiated from a Solid Substrate. 1. Theoretical Background

et al. 1999

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From a survey of the literature on grafting free radical polymerization from solid surfaces we suggest kinetic schemes for the process. The system of differential equations in partial derivatives including the diffusion equation based on the classical theory of free radical polymerization and the assumption that surface-bonded free radicals terminate by (1) reactions with bulk free radicals and (2) chain transfer to solvent or monomer are introduced. Computer simulations performed using the equations have shown good agreement with the characteristic features of the grafting process. The rate of grafting is linearly proportional to the surface concentration of the initiator and decreases as the initiation rate in the bulk increases. It follows from the concentration profiles of the bulk free radicals that free radical concentration in the vicinity of the surface can be several times larger than that in the bulk. The concentration profile depends on the distance between two surfaces. For distances less than a critical distance of about 2 μm, the concentration profile of the bulk free radicals is homogeneous.

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“…A simple evaluation on the basis of scaling theory shows that there is not a principal restriction to obtain a highly dense polymer brush using grafting from the surface by the free radical polymerization mechanism − The amount of grafted polystyrene on the surface reported by different authors reaches values of 15−100 mg/m 2 . However, there are numerous papers , reporting that the grafting amount obtained by different methods of grafting was only about 1−5 mg/m 2 (the same initiators and monomers have been used).…”

Section: Introductionmentioning

confidence: 99%

Radical Polymerization Initiated from a Solid Substrate. 2. Study of the Grafting Layer Growth on the Silica Surface by in situ Ellipsometry

et al. 1999

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Kinetics of the grafting free radical polymerization of styrene from the surface of Si wafers with a top silica layer was studied by in situ ellipsometric measurements of the grafted amount (A). Wafers uncovered and covered by physisorbed azo- or peroxide macroinitiator or covalently bonded with the substrate azo-initiator were used. Additional initiator of the same chemical nature was added to the bath solution (bulk). It was found that the grafted amount approaches a plateau value depending on the rate of grafting polymerization. At low rates, the plateau A values are on the order of 1−2 mg/m2, whereas at high rates, they are typically 10−15 mg/m2. Two kinetic regimes were studied where (1) the surface-attached chains terminate by chain transfer to the bulk or (2) the grafted chains terminate with the bulk free radicals. The rate of polymerization for the both regimes is linearly proportional to the surface density of the initiator. Within regime 2, the rate of polymerization has inverse square root dependence on the concentration of the initiator in the bulk. Two models were applied to explain the kinetics, which provide good agreement with the experimental data.

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Features of styrene polymerization initiated by peroxide initiators grafted on the aerosil filler surface

Cited by 5 publications

References 2 publications

Switching of Polymer Brushes

Switching of Polymer Brushes

Radical Polymerization Initiated from a Solid Substrate. 1. Theoretical Background

Radical Polymerization Initiated from a Solid Substrate. 2. Study of the Grafting Layer Growth on the Silica Surface by in situ Ellipsometry

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