Photopolymerisable monomers

Fig. 3.2. Monomer burette for photopolymerisable monomers. is a reservoir containing monomer over a drying agent, e.g. CaH, with magnetic stirrer. The monomer was run into A through D which was then sealed. C is a cold finger to be filled with a mush at just above the freezing point of the liquid in A, so that the condensate drips into the burette B. Any excess is returned to A via which, like and T, should be a PTFE tap. The rig should be covered in black cloth up to and 7. The latter is essential, because in its absence the monomer in A will polymerise on all the glass surfaces, even if A is kept dark. The reactor in which the monomer is required, or any phials to be filled, are attached below T. ...

Other siloxane polymers are of interest because their very low glass transition temperatures render plasticisers superfluous. However their low polarity and high hydrophobicity means that the simple commercial polydimethyl-siloxanes have high membrane resistances [92], probably due to the low solubility of ions in such media. Plasticisers could aid this but would defeat the object of using polysiloxanes in the first place. Incorporation of more polar moieties as co-monomers in the polymer, such as cyanopropyl [93], lowered membrane resistance by a factor of up to 20, with the incorporation of triflu-oropropyl groups leading to sensors for nitrate and cations [94]. Studies have also been made on using photopolymerisable crosslinkers, for example in the construction of a nitrate sensor [95]. 

Selli E, Bellobono IR. (1993) Photopolymerisation of multifunctional monomers kinetics aspects. In Fouassier JP, Rabek JP (eds.). Radiation Curing in Polymer Science and Technology Polymerization Mechanism, pp. 1-28, Springer. 

An additional advantage of the use of reactive, photopolymerisable liquid crystalline monomers with charge transfer or electroluminescent properties is the ability to generate circularly and linearly polarised light. This possibility... 

Structure on hydrogel properties of 2-hydroxyethyl acrylate determined. " Polymers bearing tertiary amino groups have been synthesised and their fluorescence spectra found to be significantly quenched while maleic anhydride " and cyclododecanones have been found to be effective initiators of the photopolymerisation of styrene. Poly(methylphenylsilane) is also an effective photoinitiator for styrenes and acrylates via a photolytic process to give silyl radicals. Iron oxalate is also an effective photo initiator for acrylate monomers while a theoretical description of the kinetics of free radical dye-initiated polymerisation via an electron transfer process has been proposed. Using the Marcus theory it has been shown that the rate of electron transfer can affect the rate of initiation. 

Some aspects of the photopolymerisation kinetics of different monomers have been investigated. The photopolymerisation rate of methyl methacrylate is accelerated in the presence of oxygen when triethylamine is present . This enhanced rate is associated with the usual oxygen-amine complex which can form a variety of species such as oxygen radical anions or hydrogen peroxide to give reactive hydroxyl radicals. The rate of photopolymerisation of methyl... 

Other workers claim a crystal violet and ascorbic acid mixture is similarly very effective in inducing the photopolymerisation of vinyl monomers. The photoinduced emulsion polymerisation of styrene with sodium dodecyl sulphate as a surfactant and dibenzyl ketone as the initiator has been... 

Triphenylsilyl ether aluminium acetylacetonate and triphenylarsonium-p-nitrophenacylide have been found to induce the photopolymerisation of acrylic monomers by a free radical mechanism while arylthiyl radicals induce the photopolymerisation of vinyl monomers (CH2=CHX) in the order X= -C(CH3)3 < -( 2)3 3 < -(CH2)Si(OCH3)3 <= -CH2Si(CH3)3 -Si(OCH3)3 -Si(CH3)3 ... 

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