PEO/PDMS

Crystallization in a range of PDMS-PEO-PDMS triblocks was investigated using dilatometry, DSC and SAXS by Galin and Mathis (1981). They found that depending on the composition of the copolymer the PEO crystallized within... 

According to the reactants, either diblock or triblock copolymers can be obtained. For instance, PEO-fc-PDMS-b-PEO triblock copolymer and PEO-PDMS diblock copolymers were prepared in high yields by hydrosilylation of a telechelic PDMS which exhibits SiH functions (Mn = 1000) with monofunctional allyl-terminated PEO with Mn = 350 and 500 and telechelic diallyl PEO (Mn = 600), respectively [123]. Their dilute solution properties were investigated. Similarly, interesting PS-b-PDMS thermoplastics have been synthesized from a polystyrene fitted at chain end with a vinyl silane function which reacts with a PDMS bearing SiH end-groups [124]. In addition, hydrosilylation has been used to prepare original copolymers from a,co-disilyl-PDMS 25 and either a,oj-diallyl-polysulfone [125] or a,oj-diallyl poly (L-lactide) (PLLA) as follows [126] ... 

For the balanced copolymer in siUcone oil, the PEO/PDMS interfacial area as increased from 0.5 nm molecule in the lamellar phase to 1.1 nm molecule in the... 

Polydimethylsiloxane vs. others PDMS/PnBMA PDMS/PtBMA PDMS/PEO PDMS/PTMO... 

Triblock PEO-PDMS-PEO copolymers have been obtained by anionic polymerization of ethylene oxide using a PDMS diol as transfer agent. These copolymers have been fully characterized by NMR and Maldi-Tof mass spectrometry. As expected, the solubility depends on the PEO/PDMS ratio [42]. 

The self-aggregation in long PEO-PDMS surfactants showed their ability to form inverse micelles and liquid crystals in nonpolar oils, including octamethylcyclotetrasiloxane (D4). These structures, which are not found in conventional hydrocarbon surfactant systems, were explained by the segregation tendency of the PEO chains and the flexibility of the siloxane chains [27],... 

Poly(ethylene oxide-6-dimethylsiloxane-6-2-methyloxazoline), PEO-PDMS-PMeOX Water 75,93,94... 

Generally, integral membrane proteins are vectorial molecules with distinct cytoplasmic and extracellular parts. They insert into cell membranes with a specific orientation. A reconstitution of aquaporin 0 with preferred orientation has been achieved by using vesicles consisting of an asjunmetric PEO-PDMS-PMOX bilayer (94). The amino terminus of the porin orients to the (ytoplasmatic side... 

Vesicle formation with block copolymers, for example with PB-poly(L-glutamate), is well documented in the literature [330]. So-called stealth liposomes could be prepared by Nuyken et al. [331] by combining phospholipids with poly(oxazoKne) based A-B-C triblock copolymers. In this context, Meier and co-workers [332 ] succeeded in preparing asymmetric membrane structures, by insertion of membrane proteins into amphiphilic A-B-C triblock copolymers with two water-soluble blocks A and C, such as PEO-PDMS-poly(2-methyloxa-zohne) of the following structure ... 

YAN Yang, J., Wegner, G., and Koningsveld, R., Phase behavior of ethylene oxide-dimethylsiloxane PEO-PDMS-PEO triblock copolymers with water, Colloid Polym. ScL, 270, 1080, 1992. 

The temperature-composition phase diagrams of these PEO + PDMS mixtures all show an upper consolute temperature and selected examples are given in Figure 3.4. Figure 3.5, on the other hand, shows selected examples of the three-component phase diagrams, with toluene as component 3, at a fixed temperature of 30 C. 

Figure 3.4 Tempemture-composition phase diagrams for various PEO + PDMS mixtures key refers to molecular weights of PEO and PDMS respectively...

One suspects that the reason why it was difficult to form reasonable emulsions at higher volume fractions, say in the 50/50 PEO/PDMS region, by this method is that nucleation and initial growth are too fast for the macrosurfactant to adsorb quickly enough (even at the higher concentrations employed) to prevent substantial coalescence of the growing droplets. 

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