Styrene polymerization kinetic analysis

Such hydrophilic macromonomers (DPn=7-9) were radically homopolymer-ized and copolymerized with styrene [78] using AIBN as an initiator at 60 °C in deuterated DMSO in order to follow the kinetics directly by NMR analysis. The macromonomer was found to be less reactive than styrene (rM=0.9 for the macromonomer and rs=1.3 for styrene). Polymerization led to amphiphilic graft copolymers with a polystyrene backbone and poly(vinyl alcohol) branches. The hydrophilic macromonomer was also used in emulsion polymerization and copolymerized onto seed polystyrene particles in order to incorporate it at the interface. 

The kinetic analysis here is based on quantitative considerations of the ideal emulsion polymerization systems which have been described qualitatively in the preceding sections. The treatment centers only around stage I and stage II (Fig. 6.18), as no general theory for stage III is available. The treatment applies to styrene-like monomers, meaning those monomers with low water solubility and those in which monomer and polymer are completely miscible over all ranges of composition. 

It has been shown [60] in the investigation of styrene polymerization in benzene that the observed rate constant greatly increases upon the introduction of small amounts of tetrahydrofuran but decreases with further addition. A detailed kinetic analysis shows that different particles are present in the system dimers ( S , Li )2, monomers (--S , Li ), monoetherates ("-S , Li , THF), dietherates (- 8 , Li , 2THF), etc. In this case monoetherate is more active than dietherate, although its activity is lower than that of the solvent separated ion pair. 

Kinetic analyses indicate that DHb is consumed during polymerization about twenty times slower than DHa. The main consumption pathway for DHb appears to be copolymerization. From kinetic analysis of photoinitiated polymerization of styrene [64], they conclude that chain transfer to monomer is negligible and that most of the chain transfer that takes place during spontaneous styrene polymerization is due to DHa (chain transfer constant 100). 

Kinetic data on olefin polymerization by polymer-immobilized zirconocene are scarce. It is generally accepted that homogeneous metallocene catalysts contain uniform active sites however, if they are immobilized on a polymer support, the MWD polymer production becomes broader compared with a homogeneous catalyst [103]. Kinetic analysis of gas-phase ethylene polymerization catalyzed by (CH3)2[Ind]2ZrCl2 bound at a hydroxylated copolymer of styrene with divinylbenzene and previously activated with MAO (0.17 wt.% Zr) has been carried out [104]. The influence of temperature (333 to 353 K), ethylene partial pressure (2 to 6 atm) and MAO level (molar ratio of MAO to zirconium from 2600 to 10,700) were studied. The activity of the catalyst in the gas-phase process changed from 5 to 32 kg PE (g of Zr atm h)It is possible that there are two types of active site. They are stable to temperature and deactivated by the same mechanism. A first-order reaction takes place. The propagation rate constants of two active sites show a similar dependence on temperature. 

The situation is less clear-cut for RAFT systems. For a dithiocarbonate-mediated styrene polymerization studied by Goto and co-workers, the steady-state kinetic analysis applied both in the presence and absence of a BPO initiator (Figure 3.10). Similarly, for the solution polymerization of methyl methacrylate, mediated by dithioesters containing a-cyanobenzyl groups in the presence of AIBN initiator, pseudo-first-order plots were obtained although a significant induction period was detected. 

Abstract The in vitro enzyme-mediated polymerization of vinyl monomers is reviewed with a scope covering enzymatic polymerization of vitamin C functionalized vinyl monomers, styrene, derivatives of styrene, acrylates, and acrylamide in water and water-miscible cosolvents. Vitamin C functionalized polymers were synthesized via a two-step biocatalytic approach where vitamin C was first regioselectively coupled to vinyl monomers and then subsequently polymerized. The analysis of this enzymatic cascade approach to functionalized vinyl polymers showed that the vitamin C in polymeric form retained its antioxidant property. Kinetic and mechanistic studies revealed that a ternary system (horseradish peroxidase, H2O2, initiator fS-diketone) was required for efficient polymerization and that the initiator controls the characteristics of the polymer. The main attributes of enzymatic approaches to vinyl polymerization when compared with more traditional synthetic approaches include facile ambient reaction environments of temperature and pressure, aqueous conditions, and direct control of selectivity to generate functionalized materials as described for the ascorbic acid modified polymers. 

The NIR-Raman spectroscopy was used by Wang et al. [163] to study the kinetics of styrene polymerizations in glass reaction flasks. Wang et al. [164], Ozpozan et al. [165], Al-Khanbashi et al. [166], Urlaub et al. [122], Bauer et al. [167], Van Den Brink et al. [168], McCaffery and Durant [169], and Elizalde et al. [170] performed similar studies forVA, styrene/butyl acrylate, MMA, cyanacrylate, styrene/ butadiene, styrene and butyl acrylate/MMA polymerizations in emulsion and miniemulsion reactions. These studies showed that NIR-Raman spectral data obtained in-line during emulsion polymerizations could be used for kinetic model building and kinetic analysis. 

The first example of a copolymerization of polar monomers in LCCP was described in our group, copolymerizing the styrene monomer (13) with isobutylene in amounts of 1-5 mol% of comonomer (Figure 3.7) (Hackethal etal, 2010). Incorporation of the polar monomer (13) can be achieved in amounts up to 2.5 mol%, as proven by NMR spectroscopy and MALDI methods. As followed by in-situ kinetic analysis, the polymerization follows a linear chain growth, together with a linear consumption of monomer when plotted as ln[Mo]/[Mt] vs. time t). 

The analysis of experimental data and the theoretical and kinetic analyses are summarized and the mechanisms of the syndiospecific styrene polymerization are clarified. 

The polymerization of styrene in liquid ammonia, initiated by potassium amide, was one of the first anionic polymerizations to be studied in detail. In this polymerization chain transfer to ammonia terminates the growth of polymer chains and living polystyrene is not formed. The reaction is of minor importance nowadays but will be briefly considered since it provides a further example of kinetics analysis. 

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