Triacrylate polymerizations

Mono-, Pi, and TriAcrylate Polymerizations Trigonal i4 Photoinitiation. The heats of polymerization of the monomers achieved by photoinitiation (light intensity approximately 5.2 meal cm 2 sec b using Trigonal 14 at approximately % concentration (Table I) were obtained from rate vs. time DSC-2 traces similar to the one shown in Figure 2 (cf. seq.). Due to the rapid... 

Figure 4.17 Fronts of triacrylate polymerization propagating side by side in two dimensions. The arrows indicate the direction of propagation.

Figure 4.18 A spin mode on the surface of a spherically expanding front of trimethylolpropane triacrylate polymerization.

Figure 4.20 shows another pattern formed by a front of triacrylate polymerization with 40% kaoHn clay, 4% dibutyl phthalate plasticizer, and 5 phr Luperox 231. Again, the mechanism of the pattern formation is unknown but it certainly affects the aesthetics of the final product. 

Lee et al. [189] realized the above idea on PhCs produced by self-assembling colloidal particles. The colloidal crystals were achieved by gravity sedimentation of 1.58 jum spherical sihca particles from a solution of dimethyl-formamide (DMF) and water. They infiltrate a precursor solution of 0.1 mM of the initiator, 9-fluorenone-2-carboxilic acid, and 0.1 M of the coinitiator, triethanolamine, in the monomer, triethylolpropane triacrylate. Polymerization was conducted using 780 nm, 80 fs, 82 MHz laser pulses. Figure 53a illustrates the procedure of their experiments. To reveal information about the polymerized structure inside the colloidal template, a Rhodamine solution in DMF was filled into the colloidal assembly after the removal of unsolidified liquid. 

Since each acrylate group is difunctional, the diacrylates are tetrafunctional while the triacrylates are hexafunctional. For polymerization ofthe polyfunctional monomers at sufficiently high degrees of conversion, the branching must result in the formation of cross-links to give a three-dimensional network. 

Fig. 15 Three-dimensional microstructures produced by 2P-initiated radical polymerization of triacrylates using q.ll or r.l as initiators a photonic bandgap structure b close-up view of the structure in (a) c tapered waveguide structure and d array of cantilevers. Reproduced with permission from [21]...

Leong et al. evaluated a hyperbranched poly(amino ester) synthesized in a novel A3+2BB B approach by Michael addition polymerization of trimethylol-propane triacrylate (TMPTA) (A3-type monomer, triacrylate), with a double molar of l-(2-aminoethyl) piperazine (AEPZ) (BB B -type monomer, trifunctional amine) (Fig. 11) [127]. To check its DNA condensation behavior and cytotoxicity, the poly(TMPTAl-AEPZ2) obtained was protonated. Due to the protonation ability of... 

Affinito [2] vapor coated hexanediol diacrylate, trimethylolpropane triacrylate, and tripropyleneglycol diacrylate hquid monomers at roughly 80°C and 1 X 10 torr onto polyethylene terephtholate and then radiation polymerized the surface using electron beam radiation. 

TABLE 1. Properties of hydrogels prepared by free radically polymerizing the corresponding triacrylate with 2,2 -azobisamidinopropane dihydrochloride. 

Figure 6. Rate of heat evolution during argon-ion laser-photoinitiated polymerization of 1-methyl-2-pyrrolidinone (MP), 9 ML of 2-ethyl-2-(hydroxymethyl)-l,3-propanediol triacrylate (TMPTA), and the dyes at a concentration of 10 m. Initiators 1) 19, 2) 18, 3) 10, 4) 16, 5) RBAX (rose bengal derivative prepared from rose bengal, which is first decarboxylated and then acetylated [36]),...

Figure 35. Rate of polymerization as a function of free energy change (-AGet) for photoinitiated CQ-NPG systems. Polymerizing monomer mixture 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate (TMPTA) and ethylated bisphenol-A dimethacrylate (bis-EMA) (1 1). Polymerization was initiated by an argon-ion laser beam. Data from Ref. [175].

The results of peroxide initiated and Trigonal 14 photoiniti-ated polymerizations of lauryl acrylate (LA), I,6-hexanediol diacrylate (HDDA), neopentyl glycol diacrylate (NPGDA), and trimeth-ylol propane triacrylate (TMPTA) will first be presented. These experiments were designed to observe total heats of polymerization under prescribed conditions. The results of more extensive rate studies on Trigonal 14 photolnitlated LA polymerizations will then follow. 

Much of the material in this section was already covered under polymerizations of di- and triacrylates in section 4.1.1. 

Figure 3.78. Scanning electron microscope images of a coin manufactured by TP initiated polymerization of tris(2-hydroxyethyl)isocyanurate triacrylate in the presence of poly(styrene-co-acrylonitrile) as binder and 167 as TP initiator using a frequency-doubled Nd YAG microlaser (0.5-ns pulses, 6.5-kHz repetition rate, wavelength 532 nm, average power 1.2 mW, 1.8-mm focal spot) (a) overview and (b) part of the coin with larger magnification. (From Ref. [136] with permission of the Optical Society of America.)...

Kempe and Barany [45] developed the CLEAR family, which is based on the copolymerization of branched PEG-containing cross-linkers such as trimethylol-propane ethoxylate triacrylate, which contain various ethylene oxide units, with amino-functionalized monomers such as allylamine or 2-aminoethylmethacrylate. These amino groups constitute the starting points for the solid-phase synthesis. The loadings of these solid supports are affected by the amount of functionalized monomer used for polymerization. Typical loadings are in the range... 

As expected, the reaction exothems from our experiments with polyfunctional urethane acrylate systems are much more complex than those found with the cationic epoxy polymerizations. Figure 5 shows results from our aliphatic triacrylate DSC runs at three temperatures under continuous illumination. 

The use of lasers to initiate the polymerization of both monofunctional and multifunctional monomers has been reported in a number of papers during the past decade. Decker (1) was the first to demonstrate that pulsed lasers could be effectively used to obtain relatively high degrees of polymerization for trimethylolpropane triacrylate. He showed that even for pulsed lasers which deliver up to gigawatts of peak power, polymerization could be effectively carried out over a wide range of conditions (1). 

In recent reports (2-7), it has been shown that it is important to consider the effect of such laser operating parameters as pulse repetition rate on the polymerization kinetics. It was clearly demonstrated that pulsing the laser at narrow time intervals on the order of the lifetime of growing polymer radical chains resulted in a premature chain termination due to injection of small molecule "terminator" radicals into the system. In this paper we focus on the effect of pulse repetition rate on the polymerization of multifunctional acrylates, in particular 1,6-hexanediol diacrylate (HDODA) and trimethylolpropane triacrylate (TMPTA). 

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