Acrylic functional materials

The developmenf of self-curing resins, i.e., systems curing without photoinitiators or, in some cases, with just small amounts of photoinitiators, has been reported recently. Such resins are synthesized by Michael reaction of acrylic functional materials with Michael donor compounds such as acetoacetates. The resulting product has an increased molecular weight compared to the parent acrylate(s). This provides resins with reduced volatility and propensity for skin absorpfion. This new technology is versatile and flexible and opens a possibility of synfhesis of a large number of different acrylate resins. The novel resins reportedly exhibit unique depth of cure capability. In the absence of a photoinitiator (PI), film of approximately 10 mils (0.25 mm) thick can be cured at a line speed of 100 fpm (30.5 m/min). When only 1% of PI is added, the thickness of film that can be cured increases to over 100 mils (2.5 mm). 

Of the many types of polymerizable materials which have been studied, acrylic functional materials have generally been found to provide the fastest cure rates by EB radiation, particularly when exposed in an atmosphere with a lowered oxygen content. The present discussions will generally refer to such acrylate-functional materials cured in an inert atmosphere. 

Silicone acrylates (Fig. 5) are again lower molecular weight base polymers that contain multiple functional groups. As in epoxy systems, the ratio of PDMS to functional material governs properties of release, anchorage, transfer, cure speed, etc. Radiation induced radical cure can be initiated with either exposure of photo initiators and sensitizers to UV light [22,46,71 ] or by electron beam irradiation of the sample. 

Organic-silica hybrid materials have been used for multi-photon microfabrication. These include the acrylate-functionalized oligosiloxanes known as ORMOCERs, which have been polymerized by radical processes using conventional IP radical iniatitors, such as c.2 [221,234]. Commercial poly(dimethylsiloxane)-based resists containing vinyl and Si-H functionalities use two different 2PA-induced processes hydrosilylation catalyzed by the photodecomposition products of Cp PtMes (Cp = ti -methylcyclopentadienyl) and radical initiation by c.4 (Fig. 13) [235]. The former process was complicated by thermally-induced polymerization. 

The performance of the new water-borne silanes was studied. The water-borne silanes were comparable to conventional silanes in most cases. In several cases, notably with acrylic latices, the new silanes excelled. In particular, the data obtained suggest that the new amine functional materials may exhibit superior performance to conventional silanes in moist environments. 

Synthetic methods targeting amino acid incorporation into functional materials vary widely. Free-radical polymerization of various amino acid substituted acrylates has produced many hydrocarbon-amino acid materials [161, 162]. In separate efforts, MorceUet and Endo have synthesized and meticulously characterized a library of polymers using this chain addition chemistry [163- 166]. Grubbs has shown ROMP to be successful in this motif, polymerizing amino add substituted norbornenes [167-168]. To remain within the scope of this review, the next section wiU focus only on ADMET polymerization as a method of amino add and peptide incorporation into polyethylene-based polymers. 

In the following sections, we give an overview of the various attempts to fabricate crosslinked layers for use in multilayer OLEDs categorized by the reactive group used in the precursor materials. We start with the [2+2] cycloaddition of cinna-mates and the radical polymerization of acrylates and styrene derivatives. The emphasis of the chapter is on our own work, which is focused on the cationic ringopening polymerization (CROP) of oxetane-functionalized materials. Finally, we summarize the less-frequently employed synthetic routes. 

Radiation curing technology is rapidly expanding into numerous, commercial applications. Due to their fast cure response, acrylate functional raw materials dominate the Industry. A wide range of acrylated monomers and oligomers is available in order to meet the various application requirements. 

For photocured polymer materials, the Persoz hardness was shown to depend mainly on the chemical structure of the prepolymer chain, on the functionality of the reactive diluent, on the photoinitiator system and on the duration of the UV exposure. The hardness of tack-free coatings thus continues to increase with further irradiation, as shown by Figure 6 for polyurethane-acrylates. This slow hardening process is likely to result from some further polymerization of the unreacted acrylic functions since their concentration was found to decrease concomittantly. 

Particle and colloidal stability, that is, lack of sedimoitation, stratification or phase separation, coagulation or flocculation, or changes in viscosity when the latex is stored, shipped, pumped, sprayed, formulated, etc. is required for most end-uses of acrylic and styrene-acrylic latexes. Such stability is primarily determined by the type and level of surfactants or other stabilizers and specialty or auxiliary monomers used. The trade-off is that functional materials contributing to particle and colloidal stability generally also increase water or moisture sensitivity, and there is an optimum balance for each end-use application. 

In a similar convergent strategy, the Monteiro group have demonstrated the preparation of well-defined, three-miktoarm star polymers using a combination of ATRP and CuAAC [108]. As discussed previously, polymers prepared via ATRP can be easily transformed by a nucleophihc displacement of the terminal halides with sodium azide to yield cUck -functional materials. In this way, PS, poly(t-butyl acrylate) (PtBA), and poly(methyl acrylate) (PMA), all of which bore a terminal azide... 

Blond, D., Barron, V., Reuther, M., Ryan, K. R, Nicolosi, V., Blau, W. J. et al. 2006. Enhancement of modulus, strength and toughness in poly(methyl acrylate)-based composites by the incorporation of poly(methyl methacrylate)-functionalized nanotubes. Advanced Functional Materials 16 1608-1614. 

The selection of polymer families treated here is somewhat arbitrary. For instance, fluoropolymers are more functional materials than engineering materials, and acrylic resins suffer enough thermal instability to be considered by some authors as outside the border of engineering plastics. However, FIFE (together with some copolymers) and PMMA have been considered because of their notoriety and some specific engineering applications. 

The basic chemistry upon curing is the homopolymerization of a (meth)acrylate functionality as is depicted in Scheme 16.26. This polymerization is a radical chain polymerization. The propagating radical is carbon-centered, and therefore this polymerization is sensitive to oxygen inhibition as oxygen can quench carbon-centered radicals very effectively. As a result of this oxygen inhibition the top layer is generally not as thoroughly cured as the bulk of the material. 

The easiest acrylates to produce industrially are the epoxy acrylates their preparation (see Scheme 16.28) starts with an epoxide-functional resin (see Section 16.4.2). In principle any epoxide-functional material can be chosen. In this reaction (meth)acrylic resin is added to the epoxide at elevated temperatures, (around 90-130°C). The (meth)acrylic acid adds to the epoxide in a ring-opening reaction resulting in an ester alcohol group. Basically this reaction is similar to the reactions used in the preparation of epoxy resins (see Section 16.4). The reactions can be either acid- or base-catalyzed base catalysis is the more frequently used, since it limits the number of possible side reactions (for instance, transesterifications). Although these reactions can be carried out in solvent, industrially they are most frequently performed in bulk. Generally these preparations are performed in a batch-type process. 

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 synthesis of homopolymers and copolymers of jt-(2,4-hexadienyl acry-late)tricarbonyliron with styrene, methyl acrylate, acrylonitrile, and vinyl acetate were first reported in 1973. These polymers could undergo protonation to yield the jt-allyliron polysalts 105. These compounds were easily transformed into new types of functional materials due to the ease of nucleophific attack on the positively... 

Vinyl-functional alkylene carbonates, useful in the preparation of polymers that contain alkylene carbonate pendant groups, can also be prepared from GC. Two examples are the reaction of GC with maleic anhydride and acryloyl chloride to produce the acrylate-functional cyclic carbonates (3 and 4, respectively. Scheme 24). Although the transesterification of alkyl esters such as dimethyl maleate or methyl acrylate by reaction with GC represents an obvious means of obtaining the above materials, the temperatures required of such processes (>100°C) result in unwanted polymerization of both the reactant and product species, even in the presence of well-known radical inhibitors such as 2,6-di-tert-butyl-p-cresol or phenothiazine. In addition, the synthesis of vinyl-functional alkylene carbonates is greatly complicated by the fact that such materials cannot be purified by distillation and must be stored at temperatures < 0 ° C in the presence of a... 

Nanocomposites based on polymer-clay systems are of considerable interest for the development of new stmctural and functional materials. Recently, there has been much research into polymer/day nanocomposites such as epoxy, acrylic,polystyrene, and polyamide-6, owing to their unique and improved properties. For instance, compared to polyamide-6, polyamide-6/clay nanocomposites at 5wt.% day loading levd had the heat distortion temperature 87 °C higher. Also the tensile strength and tensile modulus were 49% and 68% higher, while the impact strength was almost unchanged. ... 

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