Cross-linked poly copolymers

The polymers and copolymers discussed here were all prepared by reaction of the homogeneous (linear) or heterogeneous (cross-linked) poly(vinylbenzylchloride) substrate polymer with the potassium or cesium salts of the suitably monofunctionalized donors (Reaction 1). 

Copolymers of methacrylates with vinyl alcohol (Toyopearl, Fractogel) have, moreover, been successfully used as supports for the synthesis of peptides [229], oligonucleotides [230], and PNA [231]. Cross-linked poly(methyl methacrylates) [12,92,232] have also been investigated and used for solid-phase peptide synthesis. 

A similar process has been used to make polypyrrole-poly(vinyl alcohol) composites by electropolymerization from aqueous solution into a cross-linked poly(vinyl alcohol) film301 . The conductivity decreased and the elongation to break increased 10x with respect to polypyrrole. A conducting composite of 6% polypyrrole in a vinyl-idenefluoride-trifluorethylene copolymer showed an extension to break of 120% 302). 

Poly(e-CL-g-acrylamide) copolymers could be readily prepared using electron beam irradiation and Fe2+ ions provided by Mohr s salt as efficient terminators for grafted polyacrylamide chain radicals. Varying the Fe2+ ion concentration [149] enabled the average molecular weight of grafted chains to be varied within wide limits. Poly(DXO) and chemically cross-linked poly(DXO) (Scheme 20) could be grafted with acrylamide under similar conditions [150,151]. 

Nanogels Cross-linked hydrophilic copolymers, e.g., Pluronic-poly(ethylenimine) (PEI) and polyethylene oxide (PEO)-PEI Covalent conjugation of polymers 20,51,52... 

Cross-linked poly(pyrrole-g-styrene) copolymers were prepared by the electropolymerization of pyrrole in the presence of polystyrene-bound pyrrole (95). Films grown from 1 1 mixtures of pyrrole and the pyrrole-ftmc-... 

Several polymers were evaluated in the form of a surface coating on glass beads packed in columns to determine their ability to retain platelets when whole human blood passes over the surface. This ability was measured as the platelet retention index p, the fraction of platelets retained on the column. Lowest values of p were found for poly(ethylene oxide), polypropylene oxide), poly(tetramethylene oxide) (in the form of polyurethanes), and polydimethylsiloxane. Highest values (around 0.8) were found for cross-linked poly(vinyl alcohol) and the copolymers of ethylenediamine with diisocyanates. Intermediate values were found for polystyrene and its copolymers with methyl acrylate, for polyacrylate, and for poly(methyl methacrylate). The results are interpreted in terms of possible hydrophobic and hydrogen bonding interactions with plasma proteins. 

Not reported elsewhere are results on pure PDMS (fourth in Figure 2), pure polystyrene (eighth in Figure 2), cross-linked poly(vinyl alcohol) (tenth in Figure 2), and copolymers of styrene with methyl acrylate (Figure 3). 

Unlike regular block copolymer micelles which are well permeable for reagents, triblock nanospheres with hydroxylated polyisoprene coronas, cross-linked poly(2-cinnamoyloxyethyl methacrylate) shells, and poly(acrylic acid) cores, filled with Pd nanoparticles, showed slower hydrogenation of alkenes than Pd blacks due to the need for the reactant(s) to diffuse into and the products to diffuse out of the encapsulating nanospheres [13]. On the other hand, microspheres formed by diblock poly(t-butyl acrylate)-hlocfe-poly(2-cinnamoyloxyethyl methacrylate) and filled with Pd nanoparticles demonstrated good permeability and higher catalytic activity in the hydrogenation of methyl methacrylate than the commercial Pd black catalyst [14]. 

Roncali, J. [1992], Conjugated poly[thiophenes) Synthesis, functionalization, and appiications, Chem. Rev., 92, pp. 711-738. Gadgii, B., Damlin, R, Aaritaio, T, Kankare, ]., and Kvarnstrdm, C. (2013). Electrosynthesis and characterization of viologen cross linked thiophene copolymer, Electrochim. Acta, 97, pp. 378-385. Nalwa, H. S. (2001). Advanced Functional Molecules and Polymers Electronic and Photonic Properties, 3 (Gordon and Breach Science Publishers, Amsterdam, The Netherlands]. 

Ion exchange resins are cross-linked polyelectrolytes. The majority of commercial products consist of a basic framework of cross-linked copolymers of styrene with divinyl benzene. Cross-linked poly (styrene) is particularly suitable for the synthesis of ion exchange resins because the introduction of various ionically dissociating groups into the phenyl ring occurs easily. Reaction with SO3 produces a strongly acidic cationic exchange resin ... 

In much the same way as poly(acrylic acid), poly(acrylamide) serves as a tanning agent, fixative, and sedimenting agent. Copolymerization of acrylamide with a little acrylic acid yields a paper aid which, with the addition of alum, improves the wet strength of paper. The reaction of poly(acrylamide) or poly(methacrylamide) with aldehyde yields methylol compounds which are valuable aids in the textile industry. Cross-linked acrylamide copolymers can be used as enzyme carriers. 

Three-layered nanoparticles containing an hbPG core and cross-linked block copolymers based on N-isopropyl acrylate and N,N-dimethylaminoethyl acrylate as the respective arms were synthesized and proved to be thermoresponsive. ° Chu and co-workers" reported electrically conductive core-shell nanoparticles based on poly(n-butylacrylate-b-polystyrene) multiarm star polymers. The PS segments were converted to poly(p-styrenesulfonate) (PSS), thus generating amphiphilic tmimolecular micelles. Then the oxidative propagation of 3,4-ethylenedioxythiophene (EDOT) on the PSS chains was carried out by counterion-induced polymerization to produce a stable aqueous dispersion of the respective PEDOT complex. 

Poly(methacrylic acid) and its derivatives are other polymers with pH-dependent swelling. Poly(methacrylic acid) is barely hydrophilic, whereas its sodium salts are easily dissolved in water. This property is used to prepare gastro-resistant coatings for tablets. Cross-linked poly(methacrylic acid) does not swell at low pH, but its salts swell above pH 6. Such polymers and copolymers have been used as matrices for intestinal controlled delivery of drugs. Conversely, linear polymers bearing amino groups are water-soluble at low pH, whereas cross-linked polymers are swollen. Castro-soluble and... 

Commercial impact-modified acrylic resins (Table 19.15) exhibit five- to tenfold improvement in the notched Izod impact strength and the ultimate tensile elongation compared to the neat PMMA resin. These impact-modified acrylics are usually blended captively by the manufacturers of the acrylic resins. The base resin in a typical weatherable grade (Plexiglas DR, Rohm and Haas) could be a methyl methacrylate copolymer with ethylacrylate and styrene, while the rubber additive (ca. 10 %) could be an emulsion-polymerized, PMMA-grafted, cross-linked poly (n-butylacrylate) rubber of controlled particle size (<200 nm). The nonweatherable impact-modified acrylic (XT, CYRO) typically consists of a MMA/S/AN copolymer with MBS (ca. 10 %) rubber particle dispersions. 

Vinylphosphonic acid is produced in Germany and used, initially by Hoechst, later by others to manufacture a hydrophilic poly(vinylphosphonic acid) prepared by free-radical polymerization in a solvent (70,71). Poly(vinylphosphonic acid) is mainly used for the treatment of aluminum photolithography plates before application of the photosensitive layer (72,73). The coating improves the developing and printing characteristics of the plate. Dental cement applications of cross-linked poly(vinylphosphonic acid) have also been studied (74). Vinylphosphonic acid copolymers with vinylsulfonic acid have been patented as scale inhibitors for water treatment (75). 

Systematic studies on photo-cross-linking block copolymer micelles, with a core of poly(cinnamoylethyl methacrylate) (PCEMA) were published by Liu and co-workers [229]. With PAA as the shell-forming block, these authors could demonstrate by SLS, DLS, TEM and SEC that photo-cross-linking of PCEMA locked in the initial structure of the micelles without any significant change in their aggregation number and size distribution. Corecross-linking of PEO-PMAA micellar systems with Ca ions has recently been described by Kabanov and co-workers [230]. 

Helminen, A.O., H. Korhonen and J.V. Seppala (2002), Cross-linked poly(epsilon-caprolactone/D,L-lactide) copolymers with elastic properties. Macromolecular Chemistry and Physics, 203(18) pp. 2630-2639. 

---