Poly acrylics PMMA, structure

Block copolymer vesicles, or polymersomes, are of continued interest for their ability to encapsulate aqueous compartments within relatively robust polymer bilayer shells (Fig. 7) [66, 67]. Eisenberg and coworkers were the first to report the formation of block copolymer vesicles from the self-assembly of polystyrene-h-poly(acrylic acid) (PS-h-PAA) block copolymers. They also have described the formation of a wide range of vesicle architectures in solution from the self-assembly of five different block copolymers PS-h-PAA. PS-h-PMMA, PB-h-PAA, polystyrene-h-poly(4-vinyIpyridinium methyl iodide), and polystyrene-h-(4-vinylpyridinium decyl iodide) [68]. Small uniform vesicles, large polydisperse vesicles, entrapped vesicles, hollow concentric vesicles, onions, and vesicles with hollow tubes in the walls have been observed and the formation mechanism discussed. Since vesicles could be prepared with low glass transition polymers such as PB [69, 70] and PPO [71], it has been established than these structures are thermodynamically stable and not trapped by the glassy nature of the hydrophobic part. 

Depending on the chemical structure of the MAI, a suitable solvent is sometimes needed to get a homogenous state of reaction mixture. Even if using the same combination of comonomers, for example, to prepare PMMA-b-poly(butyl acrylate) (PBA), the selection of the using order of comonomers for the first step or second step would affect the solvent selections, since PMMA is not easily soluble to BA monomer, while PBA is soluble to MM A monomer [28]. 

Polymeric particles can be constructed from a number of different monomers or copolymer combinations. Some of the more common ones include polystyrene (traditional latex particles), poly(styrene/divinylbenzene) copolymers, poly(styrene/acrylate) copolymers, polymethylmethacrylate (PMMA), poly(hydroxyethyl methacrylate) (pHEMA), poly(vinyltoluene), poly(styrene/butadiene) copolymers, and poly(styrene/vinyltoluene) copolymers. In addition, by mixing into the polymerization reaction combinations of functional monomers, one can create reactive or functional groups on the particle surface for subsequent coupling to affinity ligands. One example of this is a poly(styrene/acrylate) copolymer particle, which creates carboxylate groups within the polymer structure, the number of which is dependent on the ratio of monomers used in the polymerization process. 

Fig. 1 Chemical structures of the polymers commonly used for preparation of beads poly (styrene-co-maleic acid) (=PS-MA) poly(methyl methacrylate-co-methacrylic acid) (=PMMA-MA) poly(acrylonitrile-co-acrylic acid) (=PAN-AA) polyvinylchloride (=PVC) polysulfone (=PSulf) ethylcellulose (=EC) cellulose acetate (=CAc) polyacrylamide (=PAAm) poly(sty-rene-Wocfc-vinylpyrrolidone) (=PS-PVP) and Organically modified silica (=Ormosil). PS-MA is commercially available as an anhydride and negative charges on the bead surface are generated during preparation of the beads...

Most of the remaining deviation in the correlation for UH is corrected when a term proportional to NUH, which is defined by Equation 11.20, is included. In Equation 11.20, an a-substituted acrylate is any acrylate which has a non-hydrogen substituent attached to the oc-carbon atom, namely the backbone carbon atom to which the acrylate unit is attached. The polymers which require this correction term are all structural variants of PMMA (Figure 11.2). A backbone ester unit is simply an ester (-COO-) linkage in the backbone of the repeat unit, as in poly(glycolic acid) (Figure 2.4), in contrast to an ester unit in a side group, as in PMMA. 

Acrylics. Acetone is converted via the intermediate acetone cyanohydrin to the monomer methyl methacrylate (MMA) [80-62-6]. The MMA is polymerized to poly(methyl methacrylate) (PMMA) to make the familiar clear acrylic sheet. PMMA is also used in molding and extrusion powders. Hydrolysis of acetone cyanohydrin gives methacrylic acid (MAA), a monomer which goes direcdy into acrylic latexes, carboxylated styrene—butadiene polymers, or ethylene—MAA ionomers. As part of the methacrylic structure, acetone is found in the following major end use products acrylic sheet molding resins, impact modifiers and processing aids, acrylic film, ABS and polyester resin modifiers, surface coatings, acrylic lacquers, emulsion polymers, petroleum chemicals, and various copolymers (see Methacrylic acid and derivatives Methacrylic polymers). 

Notwithstanding the general incompatibility of polymers and copolymers, polymers with solubility parameters that differ by 0.5 unit are compatible although their structures may differ. Thus, poly (methyl methacrylate) (PMMA), poly (ethyl acrylate) (PEA), poly (vinyl chloride) (PVC), and poly (butadiene-co-acrylonitrile) (90/10-60/40) form useful compatible blends because their solubility parameters are in the range 9.2-9.4. The difference in solubility parameters resulting in compatibility may be as much as one unit when the polymers are of relatively low molecular weight. 

Lately, our research on this polymer has been extended to its Interpenetrating Polymer Networks (IPNs) with poIy(acrylate)s. These materials are used as components of structural composites in the automotive and electronic industries (e.g. in printed circuit boards). Among them, the most used is that made of poly(DCPD) and PMMA 30). 

Low-MW acrylics, styrene/acrylics and poly(a-methylstyrene) blend easily with PVC and improve processing, thermoformability, gloss and ductility [33]. Commercial PMMA systems have been found to be miscible with PVC [34]. Miscibility allows improved processability by breaking the structures of PVC particles. 

---