Amphiphilic polymers block copolymers

Polymers and copolymers are among the most beneficial materials produced by synthetic chemistry. The invention and commercialization of new polymeric materials with radical new properties provides an opportunity to monopolize the market and justify the expense involved in the research and development. The commercialization of new polymers or copolymers always presents scale-up and design challenges. Scientists have recently developed new polymeric materials whose commercial impact has yet to be realized. Examples are semiconductive and conductive polymers and amphiphilic dendritic block copolymers. Other promising materials, such as polymers for (targeted) drug delivery and... 

Amphiphilic star-block copolymers can be prepared by adding a polycyclic diene such as 238 to a living diblock copolymer made by sequential ROMP of (i) the monomer in Table 9 with R = COOSiMe3, and (ii) norbomene. The trimethylsilyl ester groups are then converted to carboxylic acids by soaking the cast film of the polymer in water for 2-3 days to give a product with a hydrophobic core of polynorbomene and a hydrophilic outer layer126,502. 

The PHEMA-fe-PMPS-fc-PHEMA amphiphilic ABA block copolymers were used to generate patterned calcium carbonate hlms with dimensions of several hundreds of microns using the photolithographic properties of the polysilane component [77]. PHEMA-fe-PMPS-fc-PHEMA was spin cast from THF solution onto glass substrates. On this polymer layer continuous hhns of calcium carbonate,... 

Similar host-guest interactions are found not only with the amphiphilic star block copolymers [210,220] but also with the corresponding heteroarm [211] and core-functionalized [212] versions. Overall, these starshaped polymers induce the interaction more efficiently than their linear counterparts [220],... 

The macromonomer method (C) has also been adopted in cationic polymerization. For instance, amphiphilic graft polymers of vinyl ethers are synthesized by the cationic polymerization of a vinyl ether-capped macromonomer (26) with a block copolymer chain consisting of IBVE and AcOVE segments, followed by alkaline hydrolysis of the latter part into the HOVE units [165], This graft polymer also undergoes a host-guest interaction similar to those with amphiphilic star block copolymers [220]. 

Cheng, C.X., Tian, Y., Shi, Y.Q., Tang, R.P., Xi, F. Porous polymer films and honeycomb structures based on amphiphilic dendronized block copolymers. Langmuir 21, 6576-6581 (2005)... 

Another difiinctional monomer, endo-cis-endo-hexacydo-[10.2.l.l .l .0 .0 ]heptadeca-6,13-diene was also used for the synthesis of star polymers. Using the arm-first approach, star polymers of norbomene, 5,6-bis (methox3methyl)norbomene (DMNBE) and 5,6-bis(dicarbotri-methylsilyloxy) norbomene (TMSNBE) were obtained. Amphiphilic star-block copolymers were prepared by reacting... 

The grafting of PEG polymers onto hydrophobic, non-polar surfaces can be readily achieved by means of hydrophobic anchoring groups in an aqueous environment an outstanding example is the aqueous lubrication of the self-mated sliding of poly(dimethylsiloxane) (PDMS) by means of an amphiphilic tri-block copolymer, poly(ethylene oxide)- /ocA -poly(propylene oxide)-block-poly(ethylene oxide) (PEO-fe-PPO-b-PEO, also known as Pluronic ), as recently reported by the authors. 

Self-processes are inherent in the self-assembly of copolymers. These are composed of chemically or physically incompatible units along the same macromolecule, such as polar/hydrophobic monomers or rigid/flexible polymer segments, respectively. The most widely investigated self-assembling copolymers are amphiphilic hnear block copolymers. The chemical incompatibility between covalently linked hydrophobic and hydrophilic polymer segments drives the organization of the macromolecules into... 

Fischer, A., Brembilla, A., and Lochon, P. (2000). Synthesis of new amphiphilic cationic block copolymers and study of their behavior in aqueous medium as regards hydrophobic microdomain formation. Polymer, 42(A) 1441 1448. 

In conclusion, the well-defined organometallic amphiphilic AB block copolymer of PFS-PDMAEMA and ABC block polymers of PFP-i-PFS- -PDMS were synthesized via anionic ROP approach. ... 

Gou, P.F., Zhu, W.P., Zhu, N., and Shen, Z.Q., (2009) Synthesis and characterization of novel resorcinarene-centered amphiphilic star-block copolymers consisting of eight ABA triblock arms by combination of ROP, ATRP, and click chemistry. Journal of Polymer Science Part A-Polymer Chemistry, 47,2905. 

A styryl-type macromonomer having a water-soluble ROZO segment (Scheme 47) or having an amphiphilic ROZO block copolymer (Scheme 51) was extensively used as surfactant for the emulsion or dispersion polymerization. Polymerization of St or MMA in the presence the macromonomer as stabilizer (less than 3 wt% for the total monomer) in water took place with a radical initiator to give stable monodisperse polymer particles with a micron-size diameter. The macromonomer acted as both comonomer and stabilizer actually the copolymerization occurred. Therefore, the system is micelle forming but soap-free. Hydrophilic PMeOZO segments are preferential on the particle surface. 

For well-controlled arm number of the star polymers, an efficient approach is the use of multifunctional initiators [157,158]. For instance, the four-armed initiator, NLI-1, which was prepared by the condensation reaction of the hydroxy groups in C(CH20CH2CH2CH20H)4 with a-bromoisobutyric acid, was used in the ATRP of (2,2-dimethyl-l,3-dioxoIane-4-yl)methyl acrylate (DMDMA) with CuBr/bpy as catalyst. After isolation from the polymerization system, four-armed poly(DMDMA)s, such as NLI-2 with Mw/Mn = 1.28—1.41 were obtained, and used in the successive ATRP of MMA, giving star-block copolymers NLB-3. It is known that the cycloacetal ring is unstable in acidic conditions, so the hydrolysis of the block copolymer NLB-3 was accomplished in a 1N HCl aqueous solution to give the amphiphilic star-block copolymer structure NLB-4 as shown in Scheme 3.37 [159]. 

Figure 5 Schematic illustration of the structure formation processes in (a) polypeptides and (b) amphiphilic AB block copolymers. While the block copolymer forms micellar aggregates with a simple core-shell fine structure, the peptide organization leads to distinct nanostructures with a precise hierarchical inner structure ( primary structure the amino acid sequence of the peptide chains secondary structure locally defined substructures In a single protein molecule tertiary structure spatial arrangement of the secondary structures in a 3D structure of a single protein molecule and quaternary structure arrangement of tertiary structure subunit assembly). Reprinted with permission from Borner, H. G. Prog. Polym. Sci. 2009,34, 811-851. Copyright 2009, Elsevier.

The multifunctional initiators may be di- and tri-, azo- or peroxy-compounds of defined structure (c.g. 20256) or they may be polymeric azo- or peroxy-compounds where the radical generating functions may be present as side chains 57 or as part of the polymer backbone."58"261 Thus, amphiphilic block copolymers were synthesized using the polymeric initiator 21 formed from the reaction between an a,to-diol and AIBN (Scheme 7.22).26 Some further examples of multifunctional initiators were mentioned in Section 3.3.3.2. It is also possible to produce less well-defined multifunctional initiators containing peroxide functionality from a polymer substrate by autoxidalion or by ozonolysis.-0... 

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