Acrylic macromers

Acrylic Macromers. Thus far we have shown applications of SFC to the characterizations of monomers and crosslinkers. The next couple applications will focus upon the analysis of oligomeric methacrylates, specifically methacrylate macromers. Methacrylate macromers are frequently used as building blocks for larger architecturally designed polymers. Unfortunately, macromers far exceed the capability of GC and do not possess a chromophore for HPLC analysis. Hatada et. al. has used packed column SFC to analyzed the stereoisomers of oligomeric methylmethacrylate (MMA) prepared by anionic polymerization (13). 

Earlier, successful attempts at physically crosslinking acrylic PSAs have been disclosed in the work of Husman et al. [98], Mancinelli and colleagues [99,100] and others. Instead of making ABA type structures, these authors studied and developed the use of high macromers in acrylic copolymers. Macromers are... 

Common examples of the high Tg macromers are based on polystyrene or polymethylmethacrylate (PMMA) polymers of sufficiently high molecular weight to have a high T (typically on the order of 70-100°C as measured by differential scanning calorimetry) and also to make them immiscible with the acrylic polymer backbone once the solvent or heat has been removed. Typical molecular weight of the polystyrene or PMMA macromers is on the order of 5000-10,000 Da. Their generic structure can be pictured as in Fig. 13 (shown there for polystyrene). 

A copolymerizable group, such as an acrylate (R = H) or methacrylate (R = methyl), on one end of the molecule, and the high Tg polymer on the other end characterize the macromer. A chemically inert group, such as oxyethylene may be present to connect the two parts of the macromer. Macromers have been synthesized by different methods and some are commercially available. 

Acrylated lignin derivatives are viewed as a new and promising class of functional macromers from lignin useful for the formulation of block and segmented copolymers. 

Some of the primary comonomers that were investigated in the MACROMER studies were the acrylates, vinyl chloride, styrenes, ethylene, ethylene/propylene, acrylonitrile, and N,N-dimethyl-acrylamide. 

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. 

A polystyrene with a functionality such as a methacrylate group copolymerized with a mixture of ethyl and butyl acrylate should yield a graft structure meeting the criteria of a thermoplastic elastomer as shown in Figure 13. The data in this figure show that as the MACROMER content is increased, the tensile... 

Figure 14. Stress-strain curves for 1 1 ethyl acrylate butyl acrylate copolymers with S16MA MACROMER at 30%, 40%, and 50% MACROMER contents.

Peptidyl macromers, in which a vinyl group was introduced at the N-terminus, were synthesized by solid-phase methodology. More specifically, the peptide H-Gly-Gly-Gly-Arg-Gly-Asp-Ser-Pro-OH had acrylic acid coupled to the N-terminus. The peptidyl macromer was cleaved and deprotected by standard methods. Copolymers of styrene with these peptidyl macromers were prepared by radical copolymerization in DMF soln. Cast films were prepared from a CHC13 soln of copolymers. 

Waschinski CJ, Zimmermann J, Salz U et al. (2008) Design of contact-active antimicrobial acrylate-based materials using biocidal macromers. Adv Mater 20 104-108... 

Materials. All monomers used for synthesis were free of inhibitors and freshly distilled 2-hydroxyethyl methacrylate (HEMA) dimethyl-acrylamide (DMA) N-vinylpyrrolidone (NPV) methylmethacrylate (MMA) 2-ethylhexylacrylate (EHA) isopropylmethacrylate (IPMA) n-butyl-acrylate (BA) ethyleneglycol-dimethacrylate (EGDMA) dimethacrylate macromer obtained by reaction of 1 mol polytetramethylene oxide diol (MW 2000) with 2 mol 2,4,4-trimethyl-l,6-diisocyanatohexane and 2 mol HEMA (PX). ... 

With 2-methylpropene as M, both linear and star macromers have been prepared [92-94]. Many kinds of inifers may, of course, be used. For example Kress and Heitz prepared macromers from poly(oxytetramethylene) chains with acrylate or methacrylate end groups, by THF polymerization initiated by superacids with anhydrides as co-initiators - transfer agents [95]. 

Macromers by Controlled Initiation. New and unique graft copolymers can be prepared by copolymerizing macromers (macromolec-ular monomers) with conventional monomers. The synthesis of poly(butyl acrylate- -isobutylene), i.e., the first graft synthesis that involves carbocationic controlled initiation, has recently been accomplished by the following route (9) ... 

Furthermore, Kobayashi and co-workers prepared macromers based on polyesters with methacryloyl end groups, using lipases from different origin [72], This was accomplished by the polymerization of DDL in the presence of ethylene glycol methacrylate and vinyl methacrylate. The acryl-enzyme intermediate, formed by reaction of the lipase and the vinyl ester, reacted to terminate propagating chains. 

A very convenient method to obtain a macromer (structure 6.13) is by using an unsaturated isocyanate [50] or by using some accessible raw materials, by the reaction of a hydroxy alkyl acrylate or methacrylate with one -NCO group of a diisocyanate for example, 2,4 toluene diisocyanate (TDI) and to react the remaining -NCO group with the terminal hydroxyl group of a polyether polyol ... 

The simple esterification of acrylic or methacrylic acids, in acidic catalysis, with terminal hydroxyl groups of polyethers is a direct way to obtain macromers [47] ... 

Kim and colleagues copolymerized a number of PECs with oligomers of d/-lactic acid and terminated the resulting copolymer with an acrylate group to form photopolymerizable macromers. The resulting crosslinked polymers were evaluated as biodegradable lubricants for stainless steel needles and a potential substitute for the nonabsorbable silicones used presently. 

Martens P, Anseth KS. Characterization of hydrogels formed from acrylate modified poly(vinyl alcohol) macromers. Polymer 2000 41 7715-7722. 

Another method, namely the macromonomer (macromer) technique, has also been reported. In this method, the macromer is initially prepared by the reaction of hydroxyl-containing oil specimens with a vinyl monomer such as acrylic acid and methyl methacrylate (Rg. 8.7). This macromer is then homopolymerised and copolymerised with styrene. It is also possible to obtain the macromer by transesterification of linseed oil and castor oil. It may subsequently be homo- and copolymerised by the same method. 

Copolymerisation of acrylated vegetable oil with styrene by a macromonomer (macromer) technique. 

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