Core-shell-type copolymers

The PVC blends are usually compatibilized by addition of an acrylic copolymer, viz. ABS, MABS, MBS, or a core-shell-type copolymer (consisting of ABS-core and grafted on it acrylo-... 

More recently, we have established a preparative method for core-shell-type copolymers by the crosslinking reaction of diblock copolymer films having microphase-separated spherical cores with crosslinking reagents in the solid state [4]. The core-shell type and (AB) star copolymers have a primary structure similar to that of star pol)mier. Thus, the core-shell type and (AB) star copolymers can be expected to have supramolecular ordering. 

II. CORE-SHELL TYPE COPOLYMERS FORMED BY IMMOBILIZING DlBLOCK COPOLYMER FILMS... 

If the structure of the self-assemblies can be immobilized by crosslinking of the spherical parts (the spherical microdomains in the solid state and the core in solution), the crosslinked products should form the core-shell type copolymers (microspheres) (see Figure 1). In fact, poly[st)u-ene(S)-Z>-butadiene (Bu)-Z>-S] block copolymer micelles with cores of polybutadiene (PBu) blocks in dilute solution were stabilized by crosslinking of the chains in the micellar... 

A. Synthesis and Characterization of Core-Shell Type Copolymers... 

Structural transformation of such (AB) star copolymers can be explained by the thermal blob model, as mentioned in Section n. C. Not only the core-shell type copolymers but also (AB) star copol)nners led to hierarchical structure transformation of cubic lattice in the film formation to minimize the thermodynamic energy. 

The feature of the core-shell type polymer microspheres that differentiates them the most from the (AB)n type star block copolymers is size. The external diameters of the core-shell type polymer microspheres are generally from about 20-200 nm in the good solvents instead... 

The core-shell type polymer microspheres were synthesized upon the chemical crosslinking of the spherical microdomains in the microphase separated films. The block copolymers were dissolved in 1,1,2-trichloroeth-... 

In three dimensions, Ohta and Kurokawa [32] reported that a BCC arrangement was only slightly more favored than the FCC arrangement. In fact, many BCC structures have been reported for AB type block copolymers and the blends of homopolymer-block copolymer systems [27,33-35]. However, the lattice structure of the core-shell type polymer microspheres was FCC. This FCC formation resulted in the lower viscosity of... 

B. Alloy of the Core-Shell Type Polymer Microspheres and Block Copolymers... 

The morphology obtained from the blend of the core-shell type microspheres and AB type block copolymers with spherical morphology is shown next [37]. Figure 12 shows the typical morphologies of the blend ob-... 

Arimura H, Ohya Y, Ouchi T (2005) Formation of core-shell type biodegradable polymeric micelles from amphiphilic poly(aspartic acid)-Wock-polylactide diblock copolymer. Biomacromolecules 6 720-725... 

As was shown, the rate of graft polymerization and the composition of grafted copolymers depend on the monomer concentration, temperature, and the composition of fluorpolymer support. The former also depends on the dose of previous irradiation of the fluoropolymer support. It was assumed that the structure of the composites obtained is close to the core-shell type. 

The second way of forming nanoparticles of PE-surfs is to use water-soluble block-copolymers with one complexable (ionic) block and one non-com-plexable (nonionic) block. For example, the mesomorphous complexes (solid state) between poly(ethylene oxide)—b-poly(ethylene imine)s and dodecanoic acid can easily by dispersed in water to form nanoparticles [117]. The nanoparticles are of core-shell type and have sizes around 200 nm. Their cores are formed by poly( ethylene imine) dodecanoate while their shells consist of poly(ethylene oxide). It was found that the shapes of the nanoparticles depend on the PEI block. They are, for example, prolate if the PEI is linear and spherical if the PEI is branched. 

Huang, C.-Y., and Lee, Y.-D. (2006), Core-shell type of nanoparticles composed of poly[( -butyl cyanoacrylate )-co-(2-octyl cyanoacrylate)] copolymers for drug delivery... 

We argue that the above features of star dynamics are generic for soft systems of the core-shell type for which stars serve as prototype. Support for this comes from the dynamic light scattering (DLS) investigation of large block copolymer micelles, where all three relaxation modes, i.e., cooperative, structural and selfdiffusion are observed [188]. In particular, the star model discussed above applies to core-shell particles with a small spherical core relative to the chain (shell) dimensions. For a surface number density a = f / (47i r ) the polymer layer thickness under good solvent conditions is L ... 

PE with EVAc, CPE, BR, etc., have been chemically foamed at T = 150-210°C 5 to 95 wt% of LDPE or LLDPE with EAA PE with either poly(ethylene-co-vinylcarboxylate) or an acrylate PP with an ionomer and EBA-GMA PP with an ionomer, EBA-GMA and EPDM PO with a core-shell graft copolymer MBS-type PP with acidified-PP, or a carboxylic acid-modified EPR, SMM-MA, and either EMMA-GMA or EVAc-GMA LLDPE, PMMA and SEBS, EPR, or ethylene-styrene block copolymer (ES)... 

S-MMAIPC blend. This blend (Novacor SD-9101) was reported to have better flow, surface finish and scratch resistance than PC/polyester blends and an equivalent level of impact toughness (Table 15.24). It is believed that these formulations also include some acrylic rubber (core-shell type) for impact modification. One would expect a sufficient level of partial miscibility for self-compatibilization between the styrene-methyl methacrylate copolymer (S-MMA) and the polycarbonate especially at high MMA content of the copolymer, since the binary blends of PMMA... 

Epoxy toughening additives initially were based on rubbery inclusions or functionalized oligomers (carboxy or amine terminated butadiene/ acrylonitrile copolymers). More recently, impact modifiers (core-shell type) similar to that commonly employed with PVC have been proposed. For composites, tougher epoxy matrix candidates... 

The structure of ABS is similar to that of HIPS but with a SAN matrix instead of the PSt matrix in HIPS. PB grafted with SAN acts as a compatibilizer between the rubber particles and the SAN matrix. The rubber particle morphology in ABS can be similar to that in HIPS, with salami-type particles, but ABS particles can also be of the core-shell type, with a core of solid PB and a shell of graft copolymer, especially if the ABS is produced by the emulsion process [34]. In addition to craze formation, an important fracture mechanism in ABS polymers is shear yielding, which leads to tougher materials [46]. 

Depending on the type of charges, polycationic PEG-P(Lys) and polyanionic PEG-P(Asp) are used for the preparation of such PIC micelles (Fig. 6). Based on recent research, core-shell type PIC micelles with a 52 nm diameter were prepared from a Zn-porphyrin-dendrimer with 32 carboxylate groups on the periphery, 32(-)DPZn, and PEG-P(Lys) block copolymers (56,57). On the contrary, when the dendrimer structure is cationic, a third-generation porph3rrin-dendrimer with 32 primary amine groups on the periphery, 32(+)DPZn, and PEG-P(Asp) were used to prepare a PIC micelle, and had a spherical structure with a 55 nm-sized diameter (58). Both... 

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