Polycarbonate-poly block copolymer

See also PBT degradation structure and properties of, 44-46 synthesis of, 106, 191 Polycaprolactam (PCA), 530, 541 Poly(e-caprolactone) (CAPA, PCL), 28, 42, 86. See also PCL degradation OH-terminated, 98-99 Polycaprolactones, 213 Poly(carbo[dimethyl]silane)s, 450, 451 Polycarbonate glycols, 207 Polycarbonate-polysulfone block copolymer, 360 Polycarbonates, 213 chemical structure of, 5 Polycarbosilanes, 450-456 Poly(chlorocarbosilanes), 454 Polycondensations, 57, 100 Poly(l,4-cyclohexylenedimethylene terephthalate) (PCT), 25 Polydimethyl siloxanes, 4 Poly(dioxanone) (PDO), 27 Poly (4,4 -dipheny lpheny lpho sphine oxide) (PAPO), 347 Polydispersity, 57 Polydispersity index, 444 Poly(D-lactic acid) (PDLA), 41 Poly(DL-lactic acid) (PDLLA), 42 Polyester amides, 18 Polyester-based networks, 58-60 Polyester carbonates, 18 Polyester-ether block copolymers, 20 Polyester-ethers, 26... 

Noncrystalline aromatic polycarbonates (qv) and polyesters (polyarylates) and alloys of polycarbonate with other thermoplastics are considered elsewhere, as are aHphatic polyesters derived from natural or biological sources such as poly(3-hydroxybutyrate), poly(glycoHde), or poly(lactide) these, too, are separately covered (see Polymers, environmentally degradable Sutures). Thermoplastic elastomers derived from poly(ester—ether) block copolymers such as PBT/PTMEG-T [82662-36-0] and known by commercial names such as Hytrel and Riteflex are included here in the section on poly(butylene terephthalate). Specific polymers are dealt with largely in order of volume, which puts PET first by virtue of its enormous market volume in bottie resin. 

Polystyrene-PDMS block copolymers4l2), and poly(n-butyl methacrylate-acrylic acid)-PDMS graft copolymers 308) have been used as pressure sensitive adhesives. Hot melt adhesives based on polycarbonate-PDMS segmented copolymers 413) showed very good adhesion to substrates with low surface energies without the need for surface preparation, such as etching. 

We recently have reported our initial studies on step-growth block copolymers containing segments of poly (aryl ethers) and poly (aryl carbonates) (9,10). The multiblock [ A-B ]n block copolymers were prepared by phosgenation in methylene chloride/pyridine solution either by what was termed an in situ or by a coupled oligomer technique (JO). The choice of polycarbonates and poly (aryl ethers) for initial studies was based on the several considerations. Copolymerization is feasible since the end groups in the two oligomers can be identical, as shown in Structures 1 and 2. Considerable information is available in the... 

Figure 4. Low-temperature dynamic mechanical response of a typical block copolymer, interfacially prepared bis-A-poly-sulfone/bis-A-polycarbonate (10,000/10,000)...

Th-FFF can be applied to almost all kinds of synthetic polymers, like polystyrene, polyolefins, polybutadiene, poly(methyl methacrylate), polyisoprene, polysulfone, polycarbonate, nitrocelluloses and even block copolymers [114,194,220]. For some polymers like polyolefins, with a small thermal diffusion coefficient, high temperature Th-FFF has to be applied [221]. Similarly, hydrophilic polymers in water are rarely characterized by Th-FFF, due to the lack of a significant thermal diffusion (exceptions so far poly(ethylene oxide), poly(vi-nyl pyrrolidone) and poly(styrene sulfonate)) [222]. Thus Th-FFF has evolved as a technique for separating synthetic polymers in organic solvents [194]. More recently, both aqueous and non-aqueous particle suspensions, along with mixtures of polymers and particles, have been shown to be separable [215]. 

Besides the use of micromolecular multiinitiators, block copolymers can be obtained from macromolecular initiators. In a first step, a polymeric initiator is generally synthesized by reacting a mono- or difunctional polymer with a functional initiator. Various macromolecular initiators were prepared in this way including quite different sequences polystyrene [13, 18, 19, 25, 26], poly(dimethylsiloxane) [27], polymethylmethacrylate) [13,15,28], polyvinylacetate [28], polyvinylchloride [29, 30], polyesters [30], polycarbonate [31,32], polybutadiene [13, 25, 33], polyamide [34], polyethylene glycol) [35] or polyaromatic [36], An excellent review of the synthesis and uses of such macroinitiators was written by Nuyken and Voit [37]. Thus, only few typical examples are going to be mentioned below. 

Chen and Gardella used this surface engineering strategy to create siloxane-rich surfaces [40]. Their approach involved the blending of a homopolymer (A) with a block copolymer composed of a block with the same chemical identity as the homopolymer (A) and a block of PDMS. For all homopolymer types studied (polystyrene, poly(cc methyl.styrene) and Bisphenol A polycarbonate), XPS analysis of Si C ratios revealed a significant enrichment of the PDMS... 

The effect of dissolved CO2 on the miscibility of polymer blends and on phase transitions of block copolymers has been measured with spectroscopy and scattering (40). The shifts in phase diagrams with CO2 pressure can be pronounced. Polymer blends may be trapped kinetically in metastable states before they have time to phase separate. Metastable polymer blends of polycarbonate (PC) and poly(styrene-cn-acrylonitiile) were formed with liquid and supercritical fluid CO2 in the PCA process, without the need for a surfactant. Because of the rapid mass transfer between the CO2 phase and the solution phase, the blends were trapped in a metastable state before they... 

Ester-exchange reactions in polyesters (and analogous amide reactions in nylons) that result in a new block copolymer. An example is the formation of a blend between polycarbonate and poly(butylene terephthalate) in which the compatibilizer is formed by a transesterification reaction at elevated temperatures (350 °C), but, when processed at lower temperatures, the systems are not compatible. 

Tphe surface activity of block copolymers containing dimethylsiloxane units as one component has received considerable attention. Silicone-poly ether block copolymers (1,2,3) have found commercial application, especially as surfactants in polyurethane foam manufacture. Silicone-polycarbonate (4, 5), -polystyrene (6, 7), -polyamide (8), -polymethyl methacrylate (9), and -polyphenylene ether (10) block copolymers all have surface-modifying effects, especially as additives in other polymeric systems. The behavior of several dimethylsiloxane-bisphenol A carbonate block copolymers spread at the air—water interface was described in a previous report from this laboratory (11). Noll et al. (12) have described the characteristics of spread films of some polyether—siloxane block co-... 

Samples of styrene-dimethylsiloxane and poly (2,6-diphenyl )phenylene ether-dimethylsiloxane block copolymers were also examined as spread films. The styrene-siloxane copolymers included AB, ABA, and repeating block copolymer types. In these cases, as with the polycarbonate, the organic homopolymers do not form monolayers when we try to spread volatile solvent solutions on water. The characteristics of the copolymer spread films, however, were similar to those of the BPAC—DMS copolymers. In all cases, sigmoidal 7r-A curves were obtained, and surface pressures above 10 dynes/cm were unstable. (All of the samples examined had organic blocks of 15 or more monomer units.) A typical curve, for a styrene-dimethylsiloxane repeating block copolymer (19), is shown in Figure 4. 

By the process shown in Reaction 17, block copolymers have been constructed with hard blocks derived from polysulfones, polycarbonates, poly(BPA-terephthalates), etc. 

In order to improve the low-temperature notched impact strength of polycarbonate while still maintaining the transparency, new polycarbonate-poly(dimethyl siloxane) block copolymers were developed (Maruvada et al. 2005). These PC-siloxane block copolymers were transparent as long as the siloxane block length was kept short (<10 units), so that fine siloxane rubber domains (10-40 nm) were... 

The binary blends of polycarbonate with poly(butylene terephthalate) (PBT/PC) or poly(ethylene terephthalate) (PET/PC) are now known to be essentially phase-separated blend systems exhibiting two glass transition temperatures in each case, one for the polycarbonate-rich phase and another for the polyester-rich phase (Murff et al. 1984 Huang and Wang 1986 Wahrmund et al. 1978). The evaluation of the amorphous phase miscibility in these blends was often complicated by the potential of a transesterification reaction between the two polymers during the melt blending, which may in principle lead to a block copolymer and eventually to... 

By using this concept, resorcinol poly(ester carbonate)s were developed and introduced under the trade name Lexan SLX grades. The block copolymers of Iso- and Terephthalate esters of iJesorcinol (ITR) and BPA polycarbonate can be prepared by melt, solution, or interfacial reactions [191], The properties of these resins are controlled by adjusting the percentage of resorcinol phthalate to BPA carbonate (Fig. 14.18). 

Bosnyak, et (3) have prepared copolymers of poly(bisphenol-A-terephthalate) and bisphenol-A-poly-carbonate. These randomly coupled block or segmented copolymers are shown schematically in Equation 1. These materials deformed uniformly in tension, in contrast to homo-bisphenol-A polycarbonate where necking is observed (3). Block copolymers of bisphenol-A polycarbonates and bisphenol-A polysulfone have been investigated by McGrath, et al. (4,5,12). 

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