Methacrylate polymers star-branched

Figure 9-19. A universal gel-permeation chromatography calibration curve obtained from measurements on linear poly(styrene) (O), comb-branched poly(styrene) (O ), star-branched poly(styrene) ( ), poly(methyl methacrylate) ( ), poly(vinyl chloride) (a) c -l,4-poly-(butadiene) (A), poly(styrene)-poly(methyl methacrylate) block copolymer (Qj ), random copolymer from styrene and methyl methacrylate O), and ladder polymers of poly(phenyl siloxanes) ( ) (according to Z. Grubisic, P. Rempp, and H. Benoit).

Various types of detector have been employed for the detection of polymers separated by liquid adsorption chromatography, including conductimetric detectors for polyoxyethylenes [115] and UV detectors for ethyl methacrylate-butyl methacrylate copolymers [116]. Hancock and Synovec [117] carried out a rapid characterisation of linear and star branched polymers, particularly PS by a gradient detection method. This method measures average molecular weight in methylene dichloride solutions of the polymers and gives more specific... 

Hirao, A. and Matsuo, A. (2003) Synthesis of chain-end-functionalized poly(methyl methacrylate)s with a definite number of benzyl bromide moieties and their application to star-branched polymers. Macromolecules, 36,9742-9751. 

Hirao, A., Hayashi, M., and Matsuo, A. (2002c) Synthesis of branched polymers by means of living anionic polymerisation. 10. Synthesis of well-defined heteroarm star-branched polymers by coupling reaction of chain-functionalized polystyrenes with benzyl halide moieties with Uving anionic polymers of tert-butyl methacrylate. Polymer, 43,7125-7131. 

Watanabe, T., Tsunoda, Y., Matsuo, A. et al. (2006) Synthesis of dendrimer-like star-branched poly(methyl methacrylate)s of generations consisting of four branched polymer chains at each junction by iterative methodology involving coupling and transformation reactions. Macromolecular Symposia, 240,23-30. 

Haddleton and Crossman have recently reported a more detailed study of methacrylic multiarm star copolymers by GTP [32]. Example 5 in Table 5 is taken from this work. It was shown that the molecular weight of randomly branched PMMA armed star polymers was controlled by (1) the concentration of living arm (P ) in solution prior to addition of EGDMA, (2) the ratio of P to EGDMA, and (3) dilution of the star polymer core. The molecular weight of star increases linearly with the arm. Increasing monomer-to-solvent ratio (increasing P ) leads to increase in the number of arms per star. 

Self-assembled block copolymers are basically amphilic molecules which contain distinctively different polymers. This block copolymer contains two or more polymers quantitatively in the form of blocks. Some of the block copolymers are polyacrylic acid, polymethylacrylate, polystyrene polyethylene oxide, polybutadiene, polybutylene oxide, poly-2-methyloxazoline, polydimethyl sUoxane, poly-e-caprolactone, polypropylene sulfide, poly-A -isopropylacrylamide, poly-2-vinylpyridine, poly-2-diethylamino ethyl methacrylate, poly-2-(diisopropylamino) ethyl methacrylate, poly-2-(methacryloyloxy) ethyl phosphorylcholine, and polylactic acid. These copolymers contain more than polymers to form certain configurations like linear, branched, patterned. For example, if we take three polymers named A, B, and C, they can be combined to form arrangements AB, BA, AA, BAB, ABCAB, ABCABC, ABABAB, etc. in the form of branched configuration it forms (ABQa, (ABA)a, (AB)4, etc. Depending on the above-mentioned number of blocks, they are named as AB diblock copolymers, ABC triblock copolymers, ABC star block copolymers, etc. The covalent linkage between these different blocks of polymers makes macroscopic phase separation impossible, that is, in its place the phase separation... 

The synthesis of a miktoarm star copolymer of the type AnBn has been also demonstrated. The synthesis was performed via ATRP using divinylbenzene, as the core cross-liking agent. PEO macroinitiator chains were utilized for the polymerization of divinylbenzene forming a star polymer, with a random number of branches. The above star polymer was used as a multi-functional initiator for the polymerization of methacrylate monomers. Therefore, the synthesis of an amphiphilic miktoarm star copolymer was realized [54]. Finally, the hydrolysis of the protected methacrylate block led to the preparation of the desired DHBCs, namely the PEOn-PMAA stars. SEC analysis of the preeursor PEOn-PMMA copolymer revealed a relatively broad molecular weight distribution. Nevertheless, this is a good example for the synthesis of A Bn double hydrophilic star copolymers. 

Some polymers are linear—a long chain of connected monomers. PE, PVC, Nylon 66, and polymethyl methacrylate (PMMA) are some linear commercial examples found in this book. Branched polymers can be visualized as a linear polymer with side chains of the same polymer attached to the main chain. While the branches may in turn be branched, they do not connect to another polymer chain. The ends of the branches are not connected to anything. Special types of branched polymers include star polymers, comb polymers, brush polymers, dendronized polymers [1], ladders, and dendrimers. A cross-linked polymer, sometimes called a network polymer, is one in which different chains are connected. Essentially the branches are connected to different polymer chains on the ends. These three polymer structures are shown in Figure 1.3. 

Fig. 3.26 Universal calibration curve for crosslinked polystyrene gels with tetrahydrofuran as solvent %y linear polystyrene 0 branched polystyrene (comb type) +, branched polystyrene (star type) A, branched block copolymer of styrene methyl methacrylate x, poly (methyl methacrylate) poly (vinyl chloride) V, graft copolymer of styrene methyl methacrylate , polybutadiene (reprinted with permission from Comprehensive Polymer Science, copyright 1989, Pergammon Press pic).

---