Comb-like copolymers

Similarly comb-like copolymers of vinyl pyrollidone and vinyl alkyl amines were shown [446] to influence the permeability of negatively charged phospholipid liposomes containing encapsulated carboxyfluorescein. At a pH of approximately 7, the copolymers allowed permeability and solute release due to polymer/liposome complex formation and disruption of the phospholipid membrane. 

Oligosilanes and polysilanes initiate multidirectional growth. For example, poly(/V-vinyl carbazole) and poly(vinyl ether) side chains have been initiated from polysilanes containing several triflate groups to prepare comb-like copolymers [200-202]. 

Comb-like copolymers A combination of two polymers, one that strongly adsorbs on the surface (train configuration) and acts as an anchored backbone for the other polymer to attach and extend into the solvent. 

Barbier, V., et al.. Comb-like copolymers as self-coating, low-viscosity and high-resolution matrices for DNA sequencing. Electrophoresis, 23, 1441, 2002. 

The acid-base properties of alternating comb-like copolymers of a-olefins (C,Hi2-C igH2g) and AT,N-dimethylaminopropylmonoamide of maleic acid [32,33] [where R=C4Hg (PA-4), C Hja (PA-6), CgHi7 (PA-8), C10H21 (PA-10), C12H25 (PA-12) with n=116, 59, 40, 21 and 16, respectively], are changed as shown in Table 1. 

The moduli were calculated from the threshold of the Frederiks transition ((4.9) induced by a magnetic (Ax > 0) and electric (Ae < 0)) field in homeotropically oriented liquid crystal layers. The same order of magnitude (10 -10 dyn), which is typical of conventional nematics, has been found for elastic moduli Kn and for other nematic polymers [233, 234]. Unwinding of the helical structure of chiral nematic polymers allowed the elastic constant K22 to be calculated K22 10" dyn for an arylic comb-like copolymer with cholesterol and cyanobiphenyl side-chair mesogens [229]). 

Figure 2.3. The formation of a polyacetylene graft comb-like copolymer by direct insertion of Ziegler-Natta catalysts onto the carrier polymer, (a) The catalyst is inserted directly onto the 1,2-vinyI units, and (b) the carrier polymer is first lithiated before the addition of a Ziegler-Natta catalyst.

To realize the long-term hydrophilicity of the blend polymer membranes, the key point is to improve the stability of the hydrophilic component on the membrane surface and matrix. To this end, amphiphilic polymers have been adopted to replace linear hydrophilic PEG and PVP in membrane preparation. Theoretically, improved interactions among the hydrophobic segments in amphiphilic polymers and the fluoropolymer can improve the compatibility of the blend, and thus enhance the stability of amphiphilic polymer in the membrane matrix. Three kinds of amphiphilic polymers, viz., triblock copolymer of poly(ethylene oxide)-( -poly(propylene oxide)-ft-poly(ethylene oxide) (EPE), comb-like copolymer of polysiloxane with poly(ethylene oxide) and poly(propylene oxide) side chains (ACPS), and the hyperbranched star copolymer of polyester-g-methoxyl poly(ethylene glycol) (HPE-g-MPEG), have been... 

In an effort to adjust the interface properties of polylactide (PLA) nanoparticles used for drug delivery, copolymers were synthesized having a polypeptide block in between PEG and PLA. One copolymer was prepared by polymerization of O-protected l serine-NCA with an amino-terminated PEG. Subsequently, the deprotected serine groups were used to polymerize lactide to produce a comb-like copolymer block. This copolymer was compared with a triblock copolymer PEG-h-poly(alanine)-h-PLA. In this case, the endgroup of the poly(alanine) block was used as initiator [54]. Both types of copolymers form nanoparticles, but the copolymers with the comb-like structure show particularly interesting properties. Zeta-potential measurements indicate that the poly (serine) backbone covers the PLA core. 

Reversible deactivated radical polymerization processes, which have been referred to as living/controlled radical polymerizations, allow for producing polymeric materials with controlled molecular masses, low dispersities, and complex maaomolecular architectures, such as block and comb-like copolymers as well as star-shaped (co)polymers. In addition to nitroxide-mediated polymerization (NMP) ° and atom-transfer radical polymerization (ATRP), ° reversible addition fragmentation chain-transfer (RAFT) polymerization is an attractive new method. " ... 

Graft copolymers are also subject to phase segregation and give rise to morphologies that are different from those found in block copolymers. When each monomeric unit of the backbone carries a graft of the same length, the corresponding copolymers are called comb-like copolymers ... 

A number of fluoropolymers have been activated by various techniques [112,113— 120] thermal, corona, ozone, swift heavy ions, plasma, electron beam, or X-rays. Indeed, ozone smoothly activates fluoropolymers, in contrast to electron beam or X-ray radiation, which irradiate aU the bulk and produce peroxides in high amount. This section deals with the synthesis of fluorinated graft copolymers by the grafting from method that is, the fluorinated polymers have been first activated by ozoniza-tion or various other means (plasma, thermal, y-rays, or electrons) (first part), followed by a subsequent reaction of grafting (second part). In each part, the fluorinated comb-like copolymers can be prepared from different F-homopolymers (e.g., PTFE, PVDF, and PCTFE), and also from those arising from the different families of F-copolymers, such as FEP, ETFE, and poly(TFE-co-PAVE) (PFA). 

In the comb-like copolymers, the length of the "teeth" has an obvious impact on their crystallinity. If they are too short, the polymer is likely to... 

Molecular structures of some comb-like copolymers. See Text for description of (a) through (d). 

Jeon, H., et al., 2013. Synthesis of mesoporous MgO catalyst templated by a PDMS—PEO comb-like copolymer for biodiesel production. Fuel Processing Technology 116, 325—331. Available at http //www.sciencedirect.eom/science/article/pii/S0378382013002440 (accessed 27.04.15.). 

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