Copolymes, graft characterization

The structure of PP-g-polystyrene was studied by wide and narrow angle x-ray diffractometry. The polystyrene component formed discrete amorphous structures, which were identified after chloromethylation [143]. Structure of Rayon-Styrene graft copolymer was characterized by IR, wide angle x-ray, and SEM, grafting occurred mainly in the amorphous regions of rayon [1441. 

Uenoyama, S and Hoffman AS. Synthesis and characterization of acrylamide-N-isopropyl acrylamide copolymer grafts on silicone rubber substrates. Radiat. Phys. Chem., 1988, 32, 605-608. 

Moreover, alcohol functionalities have been introduced into the polynor-bornene (PNB) backbone by copolymerization of norbornene with a few percent of 5-acetate norbornene and subsequent acetate reduction. After transformation of the pendant hydroxyl functions into diethyl aluminum alkoxides, sCL has been ring opening polymerized (Scheme 31). Owing to the controlled/ liv-ing character of both polymerization processes the isolated poly(NB- -CL) graft copolymers were characterized by well-defined composition, controlled molecular weight and branching density, and narrow MWD (PDI=1.2-1.4) [92]. 

Random copolymers are characterized by the statistical placement of comonomer repeating units along the backbone chain. Alternating copolymers, as the name suggests, are characterized by the alternate placement of monomers. Graft copolymers are made of chemically linked pairs of homopolymers and resemble a comb. Block copolymers are composed of terminally connected structures. 

EPDM-g-PMMA was produced through ATRP with CuBr/bipyridine [80]. The graft copolymer, which had an ethylene-propylene terpolymer (EPDM) backbone and PMMA branches, was prepared from brominated EPDM that was produced with NBS to introduce allylbromine moiety on the backbone. Resulting EPDM-g-PMMA graft copolymers were characterized by solvent extraction, infrared (IR), and NMR techniques. 

The preparation of PnBA-g-PE and PtBA-g-PE graft copolymers was reported using Fe-mediated olefin polymerization, chain shuttling with Zn and ATRP techniques [108]. Terminally hydroxyl PE was synthesized from Zn-terminated PE by oxidation and hydrolysis, as referred to above. It was converted to methacrylated PE, as PE macromonomer, using methacryloyl chloride. The resulting PE macromonomer was used for the copolymerization of nBA or tBA by ATRP using CuBr/tris((N,N-dimclhylamino)clhyl)aminc. The obtained graft copolymers were characterized by GPC, DSC, and JH NMR. 

The synthesis and bulk and solution properties of block copolymers having nonlinear architectures are reviewed. These materials include star-block copolymers, graft copolymers, mik-toarm star copolymers, and complex architectures such as umbrella polymers and certain dendritic macromolecules. Emphasis is placed on the synthesis of well-defined, well-characterized materials. Such polymers serve as model materials for understanding the effects of architecture on block copolymer self-assembly, in bulk and in solution. 

Servaty, S., Kohler, W, Meyer, W. H., Rosenauer, C., Spickermann, J., Rader, H.-J., and Wegner, G., MALDl-TOF-MS Copolymer Analysis Characterization of a Poly(dimethylsiloxane)-co-Poly(hydromethylsiloxane) as a Rrecursor of a Fimctionalized Silicone Graft Copolymer, Macromolecules, 31, 2468, 1998. 

H. J., Wegner, G and Weier, A. (1998) MALDI-TOF-MS copolymer analysis characterization of a poly(dimethylsiloxane)-co-poly(hydromethylsiloxane) as a precursor of a functionalized silicone graft copolymer. Macromolecules, 31, 2458-2474. 

Macromer is a poljnnerizable macromolecular monomer, having a polymerizable end group and uniform molecular weight distribution. Macromers may be used to prepare graft copolymer containing characterized grafts with uniform and predetermined molecular weight. 

The analysis made by various researchers working on this topic include several methods. Grafted copolymers are characterized by their molar or mass grafting rates. The latter is generally obtained from the elemental analysis of the elements present in the copolymer. Serdani et al. determined fluorine and carbon in PVDF copolymer grafted by PMMA. The general structure of their copolymer is as follows ... 

Yn H, Hen X, Lu T, Sun J, Tian H, Hn J, Wang Y, Jing X. Poly(l-lysine)-graft-chitosan copolymers synthesis, characterization, and gene transfection effect. Biomacromolecules 2007 8 1425. 

Wu, Z. Meng, L. Novel Amphiphilic Fluorescent Graft Copolymers Synthesis, Characterization, and Potential as Gene Carriers. Polym. Adv. Technol. 2007,18 (10), 853-860. 

Thermal stability is an important property for PEMs, especially in high-temperature systems, and the corresponding characterization is thermogravimetric analysis (TGA). As most of the prepared aliphatic PEMs reported in the literature are block copolymers, graft copolymers, and composites of polymers, with frequently some inorganic materials included, TGA was used to study the differences between PEMs with different compositions [24,37,42,47],... 

Emulsion polymerizations of vinyl acetate in the presence of ethylene oxide- or propylene oxide-based surfactants and protective coUoids also are characterized by the formation of graft copolymers of vinyl acetate on these materials. This was also observed in mixed systems of hydroxyethyl cellulose and nonylphenol ethoxylates. The oxyethylene chain groups supply the specific site of transfer (111). The concentration of insoluble (grafted) polymer decreases with increase in surfactant ratio, and (max) is observed at an ethoxylation degree of 8 (112). 

These two parameters give the quantitative measurement of the grafting reaction. The general characterization of the graft copolymer is based on the following ... 

The selective degradation of the preformed polymer component (polycarbonate/polystyrene) of graft copolymers by two phase alkaline hydrolysis provides a clean system for quantitative recovery and subsequent characterization of the graft [151]. 

Dielectric relaxation measurements of polyethylene grafted with acrylic acid(AA), 2-hydroxyethyl methacrylate (HEMA) and their binary mixture were carried out in a trial to explore the molecular dynamics of the grafted samples [125]. Such measurements provide information about their molecular packing and interaction. It was possible to predict that the binary mixture used yields a random copolymer PE—g—P(AA/HEMA), which is greatly enriched with HEMA. This method of characterization is very interesting and is going to be developed in different polymer/monomer systems. 

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