Poly disordering transition

There are few reports on block-copolymeric TPE (namely, polyurethane, EVA, SBS, poly (styrene-fo-butyl acrylate) (PSBA))-clay nanocomposites also [196-199]. Choi et al. [196] studied the effect of the silicate layers in the nanocomposites on the order-disorder transition temperature of... 

FIGURE 5.17 Temperature versus G —the shear storage modulus at a frequency of 1.6 Hz for diblock copolymer poly(ethylene propylene)-poly(ethylethylene) (PEP-PEE). The order-disorder transition (ODT) calculated to be 291°C 1°C. (From Rosedale, J.H. and Bates, F.S., Macromolecules, 23, 2329, 1990. With permission of American Chemical Society.)... 

A reversible succession of order-order and order-disorder transition was observed for a poly(ethylene-a/f-propylene)- -poly(ethylene-co-butylene)-b-polystyrene terpolymer, which shows at room temperature non-hexagonally packed PS cylinders. Upon heating, this system reorganizes to a hexagonally packed one, and at higher temperatures dynamic-mechanical analysis indicates the transition to the disordered state [73],... 

AFM Atomic force microscopy aPP Atactic polypropylene DSC Differential scanning calorimetry HDPE High-density polyethylene iPP Isotactic polypropylene LLDPE Linear low-density polyethylene MD Microdomain ODT Order-disorder transition PB Poly(butadiene)... 

Ruokolainen J, Torkkeli M, Serimaa R, Komanschek E, ten Brinke G, Ikkala O. Order-disorder transition in comblike block copolymers obtained by hydrogen bonding between homopolymers and end-functionalized oligomers poly(4-vinylpyridine)-pentadecylphenol. Mactomolecules 1997 30 2002-2007. 

Fig. 14. Comparison oj the increase in heat content, AH (open circles), and increase in volume, A V (solid circles), for poly-tetrafluoroethylene through the order-disorder transition...

Williams, G. Dielectric information on chain mobility, chain configuration, and an order-disorder transition in amorphous poly(acetaldehyde), Trans. Farad. Soc., 59, 1397 (1962)... 

In addition to the order-disorder transition, observed for a helices, helical structures can also be induced to undergo transitions from one ordered form to another. For example, a crystalline form of poly[p-(p-chlorobenzyl)-L-aspartate] can be made to undergo a phase transition from an a-helical to an co-helical form by heating rotational entropy is computed to play a role in this process.68 Another order-order transition is the solvent-induced interconversion between polyproline 1 (with cis peptide bonds) and polyproline 11 (with trans peptide bonds), a process that has also been subjected to conformational energy calculations.85 The transition has been accounted for in terms of differences in the binding of solvent components to the peptide 0=0 groups. 

Table 23.4 Order-disorder transition temperatures of hydrogenated poly(styrene-block-diene) copolymers...

Order-Disorder Transitions. General Features, Experimental data are summarized in Table II, and representative thermochromic behaviors are shown in Figure 2. For the dialkyl-substituted polysilylenes the transition is very sharp, with a barely discernible coexistence region and an approximate isosbestic point. On the other hand, the asymmetrically substituted polymers, except poly(n-dodecylmethylsilylene), display very smooth behavior only in n-hexane solution and a broad but clearly discernible transition in dilute toluene solution. The transition width (ATc) in toluene solution was taken to be the interval between departure from the extrapolated, smooth, high-temperature behavior and the onset of peak absorption wavelength saturation at low temperature. The transition temperature (Tq) is defined arbitrarily as the midpoint of this region. 

Symmetrical Dialkyl-Substituted Polysilylenes Because of their extremely sharp order-disorder transitions, the nonpolar, symmetrical dialkyl-substituted polysilylenes are almost ideal systems with which to test the predictions discussed earlier. The predicted solvent dependence of Tc was tested by performing a series of experiments with high-molecular-weight poly(di-n-hexylsilylene) in dilute solution. Experimental results for six solvents are listed in Table II, and the theoretically defined solvation coupling constants and solvent parameters are collected in Table III. 

Several of the described eondis phases are CD glasses (Sect. 4.2-4 ami 4.6) with different paths into the glassy states. Some of these CD glasses seem to have no corresponding, stabte eondis phase, but are produced as intermediates in the path from melt to stabte erystal [polypropylene]. The ferroelectric effect of poly(vinylidene fluoride), polytrifluOToethylene and its copolymers seems coimected to eondis glass and disorder transitions (Curie temperatures). Condis states seem also to have enhanced chain mobility on mechanical (teformation. 

The disordering transition at T was rarely analyzed quantitatively. The reported data are always too small for disordering from a well order l crystal, but are usually not extrapolated to complete crystallization The existence of intermediate condis states is thus purely speculative. On cooling, it is frequent to find a direct transition of the liquid crystalline state to the LC glass (see Fig. 1.1). Placing the mesogen close to the backbone, as for example in poly(acryloyloxybenzoic acid). 

Park, K. and K. Levon. 1997. Order-disorder transition in the electroactive polymer poly(3-dodecylthiophene). Macromolecules 30 3175. 

Winokur, M.J., J. Slinker, and D.L. Huber. 2003. Structure, photophysics and the order-disorder transition to the beta phase in poly(9,9-(di- ,M-octyl)fluorene). Phys Rev B 67 184106. 

The groups of Kramer and Hawker provided an example where the target polymer could be made using sequential CFR polymerizations, but CuAAC simplified the process and made it possible to obtain the polymer with a precise molecular weight and a low polydispersity index (PDl). Attempts to make poly(benzyl methacrylate)-b-poly(butyl acrylate) with equal volume fractions of each block to be used for the determination of order-disorder transition (ODT) led to materials with imprecise volume fractions and PDls higher than 1.3. Instead, by using preformed homopolymers that were then coupled by CuAAC, the authors were able to make a small library of covalent diblock copolymers with low PDIs, while also performing fewer total reactions. 

The first successful result was seen in the grafting of poly(octadecyl acrylate) onto silica and its application for separation of PAHs in a reversed phase mode. The polymer is obtained by telomerization of octadecyl acrylate, initiated with 3-mercaptopropyltrimethoxysilane (Fig. 1). The following immobilization is carried out by mixing with porous silica in a suitable solvent. The resultant polymer-grafted silica shows, not only extremely high separation of PAHs, but also specific temperature dependency on the selectivity, which is induced by an ordered-to-disordered transition of the grafted polymer. The detail is described later. 

---