Surface-initiated atom transfer radical polymerization of polyhedral oligomeric silsesquioxane (POSS) methacrylate from flat silicon wafer

Chen, Renxu; Feng, Wei; Zhu, Shiping; Botton, Gianluigi A.; Ong, Beng S.; Wu, Yiliang

doi:10.1016/j.polymer.2005.12.025

Cited by 49 publications

(39 citation statements)

References 17 publications

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“…[ 21 ] Pyun and Matyjazewski reported the synthesis of homopolymer and block copolymers of MA-POSS with a polydispersity ( M w / M n ) of 1.14 via an atom transfer radical polymerization (ATRP) approach. [ 22 , 23 ] Chen and Zhu et al [ 24 ] carried out a surface-initiated ATRP and poly(MA-POSS) chains were grafted onto surfaces of silicon wafer. Recently, there has been considerable interest in studies on organic-inorganic hybrid block copolymers containing poly(POSS) sub-chains [25][26][27][28] and it has been reported that these organic-inorganic hybrid block copolymers can be employed as lithographic materials which can extend to sub-50 nm length.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Self‐Assembly Behavior of Organic–Inorganic Poly(ethylene oxide)‐block‐Poly(MA POSS)‐block‐Poly(N‐isopropylacrylamide) Triblock Copolymers

Zheng

Wang

et al. 2012

Macro Chemistry & Physics

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In this work, the synthesis of 3-methacryloxypropylheptaphenyl POSS, a new POSS macromer (denoted MA-POSS) is reported. The POSS macromer is used to synthesize PEO-b -P(MA-POSS)-b -PNIPAAm triblock copolymers via sequential atom transfer radical polymerization (ATRP). The organic-inorganic, amphiphilic and thermoresponsive ABC triblock copolymers are characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) and atomic force microscopy (AFM) show that the hybrid ABC triblock copolymers are microphase-separated in bulk. Cloud point measurements show that the effect of the hydrophiphilic block (i.e., PEO) on the LCSTs is more pronounced than the hydrophobic block (i.e, P(MA-POSS)). Both transmission electron microscopy (TEM) and dynamic light scattering (DLS) show that all the triblock copolymers can be self-organized into micellar aggregates in aqueous solutions. The sizes of the micellar aggregates can be modulated by changing the temperature. The temperature-tunable self-assembly behavior is interpreted using a combination of the highly hydrophobicity of P(MA-POSS), the water-solubility of PEO and the thermoresponsive property of PNIPAAm in the triblock copolymers.

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Section: Introductionmentioning

confidence: 99%

Synthesis and Self‐Assembly Behavior of Organic–Inorganic Poly(ethylene oxide)‐block‐Poly(MA POSS)‐block‐Poly(N‐isopropylacrylamide) Triblock Copolymers

Zheng

Wang

et al. 2012

Macro Chemistry & Physics

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“…[56][57][58][59][60][61][62][63][64][65] More recently, POSS nanocages, with a single polymerizable functional group per nanocage, have attracted significant attention for their potential in preparing welldefined organic-inorganic hybrid (co)polymers via living polymerization techniques. [66][67][68][69][70] However, little attention has been paid to amphiphilic block copolymers having POSS polymers as the hydrophobic block or their self-assembly. In several examples, reported in the literature, hydrophilic polymers are end-functionalized with a single POSS nanocage either at one end or at both the ends.…”

Section: Introductionmentioning

confidence: 99%

Micelle Formation and Gelation of (PEG−P(MA-POSS)) Amphiphilic Block Copolymers via Associative Hydrophobic Effects

et al. 2010

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A series of well-defined amphiphilic di- and triblock copolymers have been synthesized, using atom transfer radical polymerization, with poly(ethylene glycol) (PEG) and poly(methacrylisobutyl polyhedral oligomeric silsesquioxane) P(MA-POSS) as the hydrophilic and hydrophobic blocks, respectively. The detailed self-assembly behavior of the amphiphilic macromolecules in aqueous media was studied using both static and dynamic light scattering (SLS and DLS) techniques. The evolution of block copolymer micelle formation in THF/water mixture (20/80 v/v) was monitored as the THF evaporated from the solvent mixture. Initially the block copolymer chains existed as unimers in solution, followed by the formation of smaller aggregates (R(h) < 2 nm) after 30 min, eventually growing in size to reach an equilibrium size when all the THF evaporated within 24 h. The micelles formed by the block copolymers were found to be kinetically unstable (not frozen); i.e., they tended to revert to individual copolymer chains on dilution. The hydrodynamic radii, R(h), of the micelles varied with the degree of polymerization (DP) of the hydrophobic P(MA-POSS); for example, for PEG(5K)-b-P(MA-POSS), an increase from R(h) approximately 13.3 +/- 1.1 nm to R(h) approximately 17.5 +/- 1.4 nm was observed with a nominal change in the DP of P(MA-POSS) from 4 to 6. The micelles formed by the triblock copolymers (P(MA-POSS)-b-PEG(10K)-b-P(MA-POSS)) were comparable in size to the diblock copolymer micelles; e.g., R(h) approximately 14.0 +/- 1.3 nm was found for P(MA-POSS)(4)-b-PEG(10K)-b-P(MA-POSS)(4). The micellar structures created by the triblocks in aqueous media were "flowerlike", where the PEG middle block adopted a loop conformation in the micelle corona. In addition to micelles, larger aggregates formed by P(MA-POSS)-b-PEG(10K)-b-P(MA-POSS) were also detected in solution. The larger aggregates may suggest a contribution from some PEG blocks adopting an extended conformation with one end dangling in solution, causing gelation at higher copolymer concentrations via intermicellar interactions. The P(MA-POSS)(4)-b-PEG(10K)-b- P(MA-POSS)(4) formed a gel in water at approximately 8.8 wt % copolymer concentration. No gel formation by diblock copolymers was observed; however, the addition of a small amount of triblock copolymer to an aqueous solution of diblock copolymer results in gel formation. Finally, rheological behavior of the obtained gels was also investigated.

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“…The following optical constants (refractive index n , extinction coeffi cient k ) were used: for Si, n = 3.865, k = 0.020; for ATRP initiator layer: n = 1.500, k = 0; for PMMA, n = 1.4914, k = 0; for styrene, n = 1.5917, k = 0; for the random copolymer, n was linearly calculated according to the composition of copolymer, k = 0. [ 19 ] Three measurements were carried out for each silicon wafer and the average thickness was recorded. The static water contact angles were determined using a FTÅ200 contact angle measuring system at room temperature, and the contact angle was automatically calculated by the software.…”

Section: Methodsmentioning

confidence: 99%

Random Poly(methyl methacrylate‐co‐styrene) Brushes by ATRP to Create Neutral Surfaces for Block Copolymer Self‐Assembly

Liu

O'Mahony

Audouin

et al. 2011

Macro Chemistry & Physics

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Random copolymer brushes of styrene and methyl methacrylate (MMA) on silicon wafers by atom transfer radical polymerization (ATRP) are synthesized using CuCl/CuCl2/HMTETA. It is found that with increasing amount of styrene the thickness of the brush layer could no longer be well controlled by the amount of free (sacrificial) initiator in the reaction. At constant concentration of free initiator a constant thickness is obtained for various ratios of MMA to styrene. Within 30–70% MMA in the monomer feed the composition of the free polymer corresponds well to the monomer feed ratio, displaying a water contact angle in agreement with the theoretical value for a random copolymer. These copolymers are shown to create a neutral surface directing spin‐coated poly(styrene‐b‐MMA) into a perpendicular lamellae orientation.

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Surface-initiated atom transfer radical polymerization of polyhedral oligomeric silsesquioxane (POSS) methacrylate from flat silicon wafer

Cited by 49 publications

References 17 publications

Synthesis and Self‐Assembly Behavior of Organic–Inorganic Poly(ethylene oxide)‐block‐Poly(MA POSS)‐block‐Poly(N‐isopropylacrylamide) Triblock Copolymers

Synthesis and Self‐Assembly Behavior of Organic–Inorganic Poly(ethylene oxide)‐block‐Poly(MA POSS)‐block‐Poly(N‐isopropylacrylamide) Triblock Copolymers

Micelle Formation and Gelation of (PEG−P(MA-POSS)) Amphiphilic Block Copolymers via Associative Hydrophobic Effects

Random Poly(methyl methacrylate‐co‐styrene) Brushes by ATRP to Create Neutral Surfaces for Block Copolymer Self‐Assembly

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