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For the interpretation of the effect of lithium butoxides on the rate of the styrene anionic polymerization, quantum-chemical DFT calculations of their aggregation and dissociation behavior in polar solvents were performed. The calculations showed that addition of n-BuOLi should lead to the preferable scavenging of free Li + -cations by the tetrameric THF-solvated aggregates of the alkoxide,...
Strategies for avoiding secondary particle formation in seeded emulsion polymerisation, based on a simple model for particle nucleation [Macromol. Symp. 92 (1995) 13], are discussed and exemplified in the context of growing latex particles with polystyrene cores and poly(vinyl acetate) shells. With a polystyrene seed of unswollen radius 44nm, core-shell polymerisation was easily achieved. However,...
This paper discusses the influence of dialkylphenoxyaluminum additives on the retardation of styrene polymerization initiated by alkyllithium. Data are compared with results obtained with trialkylaluminum. Similar decreases of the propagation rate can be achieved with both types of compounds. Although with R 3 Al additives (i-Bu 3 Al, Et 3 Al, Me 3 Al), reactivity extinction...
The anionic dispersion copolymerization of styrene and butadiene was investigated. The suitability of the lower alkanes butane and pentane as dispersing media was tested. Only pentane turned out to be suited for the synthesis of non-aggregated polymer particles. Following block copolymerization experiments, the active chain ends were found to be homogeneously distributed over the whole particle volume...
Electrosterically stabilized polystyrene latexes with a poly(acrylic acid) hydrophilic layer with either perdeuterated core or perdeuterated hydrophilic layer were prepared in situ in a styrene/acrylic acid copolymerization, in a manner similar to that commonly employed industrially. Small angle neutron scattering (SANS) measurements were made over a range of contrasts for three latexes at high and...
The bulk radical polymerizations of styrene (St) at 80-120 o C in the presence of 6-aza-7,7-dimethyl-9-hydroxyspiro[4.5]decane-6-yloxyl (1) and 1-aza-2,2-dimethyl-4-hydroxy[5.5]undecane-1-yloxyl (2) were studied. At 100 and 120 o C, the polymerizations were well controlled by those nitroxides to give poly(St)s with narrow polydispersities. On the other hand, the polymerization mediated...
An unconventional amphiphile (1-[ω-(4′-methoxy-4-biphenylyloxy)octyl]pyridinium bromide, PC8) was used as surfactant in the emulsion polymerization of styrene. At low surfactant concentration (6, 12 or 36 mmol l −1 ), curves of polymerization rate versus conversion obeyed the typical behavior characterized by intervals I, II and III. However, at high concentration (48 or 72 mmol l −1 ...
For the interpretation of the effect of such π-donors as durene and tetraphenylethylene on the observed rate constant of the styrene anionic polymerization in cyclohexane, quantum-chemical DFT calculations of the structures and relative stabilities of the polymerization active sites, their dimeric associates and complexes with the π-donors were performed. It was shown that π-donors stabilize the propagating...
The solution copolymerization of styrene/butyl acrylate in toluene was monitored off-line using an ATR-FTIR probe. The probe was used to track the concentration of the starting materials, thereby providing conversion and polymer composition data. Off-line gravimetry and 1 H NMR spectroscopy were used as standard methods to provide a comparison to the ATR-FTIR data. A non-calibrated univariate...
Protocols were examined for the measurement of rates and enthalpies of polymerization (ΔH p ) using reaction calorimetry. ΔH p was determined to be 70.2kJmol −1 for a series of seeded styrene emulsion polymerizations under typical emulsion conditions, in good agreement with literature values. However, there was a significant deviation from this value for small-particle systems,...
Objective: the objective of this study is to prepare high vinyl copolymers containing various levels of styrene and butadiene, and also to prepare random butadiene in high styrene content styrene–butadiene copolymers (SBR) while controlling the styrene block length. These materials could be used in race tread applications. Summary: This reports presents the synthesis and characterization of random,...
A well-defined, amphiphilic poly(styrene-co-acrylic acid) copolymer was synthesized in a single step by nitroxide-mediated controlled free-radical copolymerization of styrene and acrylic acid, without protection of the acid groups: M n =6500gmol −1 , M w /M n =1.5 and a composition of F AA =0.70±0.03 in acrylic acid. In addition to the good control over molar...
The effects of various components in an emulsion polymerization system on the dissociation rate coefficient of persulfate at 50°C are examined using iodometry. Styrene monomer is found to enhance greatly the dissociation, while there is either no effect or possibly a slightly reduced rate of dissociation with methyl methacrylate monomer. The saturated analogues of these monomers (ethylbenzene and...
A novel method based on the steady state fluorescence technique was used to study the sol–gel transition in the free radical crosslinking reaction between styrene (St) and divinyl benzene (DVB) with 2,2′-azobisisobutyronitrile (AIBN) as initiator. N-(4-(pyrenyl methylene)-oxycarbonyl phenyl)maleimide (Py-MI) was used as a fluorescence probe. The possible enchainment of Py-MI in alternating sequences...
A new cyclic nitroxide 1 and the corresponding alkoxyamines 9 and 10 were synthesized and the polymerization of styrene (St) initiated with 10 was investigated. The NO–C bond of 9 is very weak, cleaving at room temperature. On the other hand, alkoxyamine 10 is stable at room temperature and the A act and E act for the NO–C bond homolysis were determined to be 1.4×10 15 s ...
A novel benzodithioate compound with a pyrene structure in the R group, pyrenylmethyl benzodithioate (PMB) was synthesized. Using PMB as the chain transfer agent (CTA), the RAFT polymerizations of styrene with AIBN as an initiator were carried out in different reaction conditions. The results indicated that PMB was an effective CTA for the RAFT polymerizations of styrene with the “living”/controlled...
The morphologies of synthesized poly[acrylic acid-b-styrene-b-isobutylene-b-styrene-b-acrylic acid] pentablock terpolymers were investigated using transmission electron microscopy, atomic force microscopy, small angle X-ray scattering, and indirectly by dynamic mechanical analysis and degree of water sorption. These materials possess considerable order within three-phase morphologies that contain...
Trialkylaluminum and sodium hydride form hydrocarbon soluble heterocomplexes which were used as initiating systems for the retarded anionic polymerization of styrene in hydrocarbon media at high temperature and in concentrated monomer, corresponding to conditions close to those used in industry for styrene radical polymerization. To be active towards styrene polymerization in hydrocarbons, these systems...
Reversible addition–fragmentation chain transfer polymerization (RAFT) of styrene (St) was carried out in the presence of oxygen using 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) or benzyl (2-phenyl)-1-imidazolecarbodithioate (BPIC) as the RAFT agent. The characteristics of the “living”/controlled radical polymerization were observed at high concentration of RAFT agent and low polymerization temperature...
The ansa-metallocene complex (CpCMe 2 Flu)Nd(C 3 H 5 )(THF) (1) is an effective single-component catalyst for the production of syndiotactic styrene-rich polymer materials modified by isoprene and/or ethylene. The recovered copolymers have high molecular weights (M n =12,000–91,000g/mol) and unimodal, relatively narrow molecular weight distributions (M w /M...
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