Silica polystyrene-grafted

According to Tsubokawa et al. (18), the molecular weight of grafted polystyrene from radical polymerization at the surface of silica is considerably higher than that from cationic polymerization. 

Fig. 34. Stability boundary for silica spheres (a = 115 nm) bearing grafted polystyrene chains (M = 7.5 kg/mol) in solution of polystyrene (M = 31 kg/mol) in toluene (Edwards et al., 1984).

The most common trityl anchor was monomethoxytrityl (Figure 19.5), employed in the phosphodiester method on PS-1% DVB by Melby and Strobach [146], on macroporous PS by Roster and Cramer [159] and on PTFE grafted polystyrene by Potapov d. al. [167] A dimethoxytrityl linker was used by Roster and Cramer for the phosphodiester chemistry on popcorn PS [144] and by Belagaje and Brush [155] for their original adaptation of the phosphotriester method for the synthesis in 5 -to-3 direction (Figure 19.5). Roster has also described a trityl anchor linked to a silica gel support [185]. Similar linkers have been exploited for liquid-phase oligonucleotide synthesis (Section 19.4). 

We conclude that provided the anchor polymer is attached sufficiently strongly to the colloidal particles, its chemical nature has no significant bearing on the observed CFPT. This conclusion is buttressed by the studies of Clarke and Vincent (1981a) who covalently grafted polystyrene chains on to silica particles and so obviated the need for an anchor polymer. The pattern of incipient flocculation observed for these systems conforms with that detailed in this chapter for stabilizing moieties anchored by polymer chains. 

RAFT polymerization used to graft polystyrene onto silica nanoparticles... 

Liu CH, Pan CY (2007) Grafting polystyrene on to silica nanoparticles via RAFT polymerization. Polymer 48 3679-3685... 

Brzozowska AM, de Keizer A, Norde W, Detremblenr C, Cohen Stuart MA (2010) Grafted block complex coacervate core micelles and their effect on protein adsorption on silica and polystyrene. Colloid Polym Sci 288 1081-1095. doi 10.1007/s00396-010-2228-4... 

The homopolymer of styrene which is formed in addition to the graft polystyrene is separated from the graft product by extraction with toluene. The amount of homopolymer is determined gravimetri-cally, and the amount of polystyrene grafted onto silica, by elementary analysis or loss on ignition. 

TchoulMN, Dalton M, Tan L-S, et al Enhancing the fraction of grafted polystyrene on silica hybrid nanoparticles. Polymer 53 79-86, 2012. 

Sunday D, Curras-Medina S, Green DL (2010) Impact of initiator spacer length on grafting polystyrene from silica nanoparticles. Macromolecules 43(11) 4871 878... 

The original catalyst for this reaction is Pd(PPh3)4. Heterogenization of this catalyst was attempted by grafting it onto functionalized polystyrene or modified silica gels,185 which increased significantly the selectivity for the reaction of 3-acetoxy-5-carbomethoxy-l-cyclohexene with diphenylamine. Data concerning the stability of these solids are, however, not reported. 

The sorbents were hydrophobic Teflon, hydrophobic polystyrene (PS), and hydrophilic silica. These sorbents were negatively charged colloidal particles having smooth surfaces. In adition, PS particles at the surface of which oligomers (8-mers) of ethylene oxide ((EO)8) were grafted at a... 

In this paper we describe methods in which polystyrene (PS) and polydimethylsiloxane (PDMS) have been successfully grafted to silica particles, avoiding the dry stage. 

In this case some of the Sll silica was freeze-dried and degassed at 10-3 Torr and 150°C and then reacted with trichloromethylsilane in the vapour phase this replaced the surface hydroxyl groups by chloro groups. The particles were then redispersed (with the aid of ultrasonics) in a 4 1 volume ratio toluene THF solvent mixture. "Living" polystyrene (PS19), in a similar solvent mixture was then introduced and the grafting reaction allowed to proceed for 24 hr at room temperature. 

Figure 3.8. An early example of a hybrid support applied in the rhodium catalysed hydroformylation operated in a continuous flow reactor. Polystyrene containing phosphite ligands were grafted on inorganic silica, such that the catalyst will behave as a homogeneous catalyst when using a compatible solvent...

Zhao B (2004) A combinatorial approach to study solvent-induced self-assembly of mixed poly (methyl methacrylate)/polystyrene brushes on planar silica substrates effect of relative grafting density. Langmuir 20 11748-11755... 

In 2005, Jerome and co-workers investigated the selective monoesterification of sucrose with various fatty methyl esters, in the presence of a strongly basic guanidine (triazabicyclo[4.4.0.]dec-5-ene (TBD)) grafted either over silica (HMS-TBD) or a polystyrene support (PS-TBD) (Scheme 12) [129]. 

Fig. 12.1.1 Dependence of order parameter, S. of the secondary polymer, spin-labeled poly (methyl methacrylate) (PMMA) and polystyrene (PST), bound to poly(maleic anhydride—styrene )-grafted silica on hexane content in ethyl acetate-hexane cosolvent. Numbers in parentheses are number average molecular weight of the secondary polymer. (From Ref. 48.)...

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