3 acrylate terminal groups

The dimeric model compounds studied can be classified into two groups. The terminal radical can have either an acrylate or a methacrylate structure. Model dimeric radicals with an acrylate terminal group were generated in the reaction of the... 

Silicone with vinyl-terminal groups is commonly UV-cured for release coatings. These materials have been combined with silicate tackifiers and acrylate monomers to make PSA compositions as well [55]. 

The two matrices in these cements are of a different nature an ionomer salt hydrogel and polyHEMA. For thermodynamic reasons, they do not interpenetrate but phase-separate as they are formed. In order to prevent phase separation, another version of resin glass polyalkenoate cement has been formulated by Mitra (1989). This is marketed as VitraBond, which we term a class II material. In these materials poly(acrylic acid), PAA, is replaced by modified PAAs. In these modified PAAs a small fraction of the pendant -COOH groups are converted to unsaturated groups by condensation reaction with a methacrylate containing a reactive terminal group. These methacrylates can be represented by the formula ... 

Figure 13. Tan 5 as function of temperature for cross-linked films of three different acrylate resins with either hydroxyl (HI 3), benzoate (HI 2), or propionate (H11) terminal groups.

A second test was done by using butyl acrylate as the comonomer as shown in Figure 11. The reactivity ratios in this case are such that the methacrylate functionality would react slower with acrylates than with vinyl chloride. As predicted the butyl acrylate is at 62% conversion before the MACROMER peak is significantly diminished. These data add validity to the hypothesis that the placement of side chains in the backbone is dependent on the terminal group of the macromonomer and the relative reactivity of its comonomer. 

In the case of poly-bomyl-acrylate, the slight increase in rotatory power of low-molecular-weight polymers (134) might be attributed, at least in part, to the high contribution given by the terminal groups. 

Epoxy acrylate resins or vinyl esters are made from the esterification of epoxy resin via their terminal group with an unsaturated acid, such as methacrylic acid derived from epoxy resin. A typical reaction sequence is illustrated in Fig. 4.3. The resultant polymer is usually dissolved in a reactive monomer such as styrene. 

The reductive cyclization of epoxides with alkenes and alkynes provides a very useful method for the synthesis of complex carbocyclic ring systems. Several interesting applications of this methodology have been reported in the past year. Two examples report the cyclization of an epoxide with an acrylate as the terminating group <07T 11341 ... 

The nature and number of the terminal groups, the type of bonds, the presence of aromatic cycles and carbonate groups in the unsaturated ester molecule, as well as other structural features affect polymer flammability. The slope of the straight lines increases from methacrylate to acrylate polymers. Thus, for polymers of alkylene glycol dimethacrylates it is 2,82x 10 kJ/kg, for polymers with carbonate bonds 2.86 X 10 -2.9 X 10 kJ/kg for acrylic polymers it is somewhat higher, 3.27 x 10 kJ per kg. Linear polymers, e.g. PMMA, PE, etc. have a smaller slope corresponding to... 

The general radical copolymerisation reaction for synthesis of acrylic polyols is shown in reaction 10.1. It is obligatory that one of the comonomers is a hydroxyalkyl acrylate or hydroxyalkyl methacrylate (mainly hydroxyethylacrylate and hydroxyethylmethacrylate) in order to introduce hydroxyl groups (as lateral groups, not as terminal groups) available for the reaction with -NCO groups of diisocyanates (reaction 10.1). 

Poly(2-alkyl oxazoline)s having methacrylate or acrylate end groups were prepared by two methods [182]. a) Living polyoxazoline chains, prepared using methyl p-toluene sulphonate as initiator, were end-capped by reaction with metal salts or tetraalkylammonium salts of acrylic or methacrylic acid or a trialky-lammonium salt or trimethylsilyl ester of methacrylic acid (functional termination). b) The living polymers were terminated with water in the presence of Na2C03 to provide hydroxyl-terminated chains. Subsequent acylation with acry-loyl or methacryloyl chloride in the presence of triethylamine led to the formation of the macromonomers. The procedures are outlined in the following Scheme 51. 

Although the exact structure of the copolymer is not known, it is convenient to consider that the reaction leads to a crosslinked copolymer. This is based on the assumption that the acrylate epoxide groups are truly grafted onto the PP chains and are not all at terminal sites. The latter structure could result from PP decomposition in the presence of radical initiator, followed by trapping the terminal radical by monomeric acrylate epoxide. 

The thermal lability of the R—C—O—N bond system controls the reversibility of the chain termination and limits also the use of NMRP. SFRP of styrene at about 130°C is studied intensively. In this case, high control and high molar mass products could be achieved. It was found that the thermal autopolymerization of the styrene monomer plays an important role in the mechanism of the reaction. Therefore, first experiments using different monomers in the presence of TEMPO and a radical initiator failed with regard to the control. However, new nitroxide adducts with a different R—O—N bond stabiUty have been developed, for example, by Hawker [14], which work also for styrene derivatives as well as for acrylates. End group functionalization in NMRP can be achieved by using a functional radical initiator in combination with a stable radical or functionalized nitroxide adducts. 

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