Polyisoprene /PDMS

DeLeo et al. (2011) and DeLeo and Velankar (2008) prepared compatibilized blends of polyisoprene-PDMS (70-30 and 30-70) with addition of 0.1-3.0 wt% copolymer of MA-f-polyisoprene and amine-f-PDMS. Characterization methods included optical microscopy and rheology. 

The study of acid-base interaction is an important branch of interfacial science. These interactions are widely exploited in several practical applications such as adhesion and adsorption processes. Most of the current studies in this area are based on calorimetric studies or wetting measurements or peel test measurements. While these studies have been instrumental in the understanding of these interfacial interactions, to a certain extent the interpretation of the results of these studies has been largely empirical. The recent advances in the theory and experiments of contact mechanics could be potentially employed to better understand and measure the molecular level acid-base interactions. One of the following two experimental procedures could be utilized (1) Polymers with different levels of acidic and basic chemical constitution can be coated on to elastomeric caps, as described in Section 4.2.1, and the adhesion between these layers can be measured using the JKR technique and Eqs. 11 or 30 as appropriate. For example, poly(p-amino styrene) and poly(p-hydroxy carbonyl styrene) can be coated on to PDMS-ox, and be used as acidic and basic surfaces, respectively, to study the acid-base interactions. (2) Another approach is to graft acidic or basic macromers onto a weakly crosslinked polyisoprene or polybutadiene elastomeric networks, and use these elastomeric networks in the JKR studies as described in Section 4.2.1. 

Thermodynamic Analysis. As reported previously, the storage modulus G of PDMS networks with tetrafunctional crosslinks is independent of frequency between 10 3 and 1 Hz (21). This behaviour which is entirely different from that of vulcanized natural rubber or synthetic polyisoprene networks, was attributed to the lack of entanglements, both trapped and untrapped, in these PDMS networks. Figure 4 shows that G of a network with comb-like crosslinks is also frequency independent within an error of 0.5%. For comparison, two curves for PDMS having tetrafunctional crosslinks are also shown. The flat curves imply that slower relaxations are highly unlikely. Hence a thermodynamic analysis of the G data below 1 Hz can be made as they equal equilibrium moduli. 

Randomly - Crosslinked PB and PI. Polybutadiene (Diene 35 NFA, Firestone Tire and Rubber Co.) and cis-polyisoprene (Natsyn 2200, Goodyear Tire and Rubber Co.) were crosslinked with dicumyl-peroxide, as for PDMS. Mc values were also calculated by means of equation 2. They are given for PI in Table I and are listed for PB in reference 2. 

Fig. B8.2.2. Logarithmic plot of the correlation time versus T — Tg for DIPHANT dispersed in polybutadiene (PB), polyisoprene (PI) and poly(dimethylsiloxane) (PDMS). The broken lines are the best fits with the WLF equation (reproduced with permission from Bokobza and Monneriea ).

A pseudo solid-like behavior of the T2 relaxation is also observed in i) high Mn fractionated linear polydimethylsiloxanes (PDMS), ii) crosslinked PDMS networks, with a single FID and the line shape follows the Weibull function (p = 1.5)88> and iii) in uncrosslinked c/.s-polyisoprenes with Mn > 30000, when the presence of entanglements produces a transient network structure. Irradiation crosslinking of polyisoprenes having smaller Mn leads to a similar effect91 . The non-Lorentzian free-induction decay can be a consequence of a) anisotropic molecular motion or b) residual dipolar interactions in the viscoelastic state. 

Functionalized polysiloxanes are attractive because, with only small modification of the polysiloxane properties (e.g. density, yield strength, etc.), they allow reduction in the interfacial tension thanks to better interactions with the other homopolymer. Two studies involving PB/PDMS and polyisoprene (PIP)/PDMS are of particular interest [19,20]. The PDMS end groups were either amine (-NH2) or acid (-COOH). It was first observed that the PB/PDMS-NH2 system exhibits a 30% reduction in interfacial tension compared to the equivalent PB/PDMS system. A preliminary reduction... 

Abstract Polyferrocenyldimethyl-silane (PFS) diblock copolymers with polyisoprene (PFS-PI) or with polydimethylsiloxane (PFS-PDMS) self-assemble in simple alkane solvents to form what appear by TEM to be dense flexible cylinders (nanowires) or nanotube-like structures. Typical widths are on the order of 20 to 30 nm, with variable lengths often greater than 10 un. The structures that form, and the dimensions of the tube-like structures or wires, depend upon the composition of the polymers and the lengths of the blocks. Light scattering experiments show that the PFS-PDMS (block ratio 1 12) solutions aged... 

Figure 5.1. Molecular structures of the chemical repeat units for common polymers. Shown are (a) polyethylene (PE), (b) poly(vinyl chloride) (PVC), (c) polytetrafluoroethylene (PTFE), (d) polypropylene (PP), (e) polyisobutylene (PIB), (f) polybutadiene (PBD), (g) c/5-polyisoprene (natural rubber), (h) traw5-polychloroprene (Neoprene rubber), (i) polystyrene (PS), (j) poly(vinyl acetate) (PVAc), (k) poly(methyl methacrylate) (PMMA), ( ) polycaprolactam (polyamide - nylon 6), (m) nylon 6,6, (n) poly(ethylene teraphthalate), (o) poly(dimethyl siloxane) (PDMS).

PE, polyethylene PS, polystyrene PDMS, polydimethylsiloxane PIB, polyisobutylene PMMA, (atactic) polymethylmethacrylate l,4PBd, 1.4-polybutadiene 1,4PI, 1,4-polyisoprene. 

Cylindrical and tape-like morphologies have been identified in the case of PI-/ -PFS (PI = polyisoprene) where the PFS block crystallizes. " Water-soluble polyferrocenyldimethylsilane-/ -poly(aminoalkylmethacrylate) co-polymers of narrow polydispersity have also been prepared and cylindrical micelles have been identified. " Block co-polymers generated by transition metal-catalyzed ROP, such as PFS-/ -PDMS-/ -PFS triblock materials, have been shown to self-assemble in hexanes to yield a variety of remarkable architectures that include flower-like assemblies where the... 

The sensing materials used are polyisobutylene (PIB), polyepichlorohy-drin (PECH),polydimethylsiloxane (PDMS),polyisoprene (PIP), and polybutadiene (PBD) ... 

Semiconductor device arrays were examined to classify the agents at different operating temperatures. In addition, the sensing properties of an array could include different sensing membrane SAW sensors (polyisobuth-ylene (PIB), polyepichlorohydrin(PECH), polydimethysiloxane (PDMS), polybutadiene (PBD), and polyisoprene (PIP)). 

A PV process characterized by excellent separation efficiency nsing a membrane that comprised an elastomeric polymer matrix containing zeolite was patented by Hennepe et al. (1990). A preferred group of such elastomeric polymers are silicone rubbers, especially polysiloxane rubbers and in particular polydimethylsiloxane rubber the nitrilebutadiene rubbers (NBR) polyisobutylene, and the polyisoprene, and styrenebutadiene copolymer rubbers. Zeolites were incorporated into the membranes to make them as hydrophobic as possible. These membranes were particularly suitable for the separation of hydrocarbons, alcohols, esters, ethers, and amines from aqueous solutions containing these impurities by PV. PDMS is the most well-known membrane material for the extraction of VOC from aqueous waste stream by PV. Although it is quite permeable and selective to many VOCs in water, its selectivity can be improved further with appropriate zeolite fillers. Such improvement may be needed for polar solutes such as aroma and fermentation products, whose high value makes the PV process attractive. 

The influence of compatibilizer concentration on the two relaxation times also was analyzed by Van Hemelrijck et al. (2004). They have fitted the Palierne model with an interfacial shear modulus by introducing a concentration gradient of the block copolymer along the interface. Figure 1.3 presents the dynamic moduli of compatibilized blends—polydimethylsiloxane (PDMS)/polyisoprene (PI)—at various ratios of compatibilizers versus angular frequency (Van Hemelrijck et al. 2005). 

FIGURE 1.5 Variation of the first normal stress difference versus strain for (O) uncompati-bilized blends of polydimethylsiloxane (PDMS) in polyisoprene (PI) and for ( ) 10% com-patibilized blends of polydimethylsiloxane (PDMS) with polyisoprene (PI). (Adapted from Van Hemelrijck Ellen. Effect of physical compatibilization on the morphology of immiscible polymer blends. PhD thesis, K U Leuven, 2005.)... 

Systematic smdies on the microdomain morphology of linear ABC Mblock terpolymers (hereafter called linear ABC) are limited to several systems. Linear ABC samples were predominantly synthesized by sequential living anionic polymerizations, which limit the kinds of monomers. Thus, polystyrene (PS) and polyisoprene (PI) or polybutadiene (PB) as well as their hydrogenated polymers such as poly(ethylene-a/t-propylene) (PEP) or poly(ethylene-aft-butylene) (PEB) were used as the A and B blocks, while poly(2-vinylpyridine) (P2VP), poly(4-vinylpyridine) (P4VP), poly(methyl methacrylate) (PMMA), poly(tert-buthyl methacrylate) (PtBMA), poly(ethylene oxide) (PEO) or polydimethylsiloxane (PDMS) was used as... 

PANI, polyaniline MMT, montmorillonite PEO, poly(ethylene oxide) PI, polyisoprene PP, polypropylene MA, maleic anhydride PVDF, poly(vinylidene fluoride) PA6, nylon 6 PET, poly(ethylene terephthalate) PU, polyurethane PHA, poly(hydroxyalkanoate) PE, polyethylene PDMS, poly(dime-thylsiloxane) PLPVS, poly(vinylsilsesquioxanes) PLLA, poly(L-lactide) BR, butyl rubber PTT, poly(trimethylene terephthalate) PVME, poly(vinyl methyl ether) NR, natural rubber NBR, nitrile rubber. 

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