Poly telechelic polymers

Boraindane 178 <1996CHEC-II(8)889> was applied to the preparation of new telechelic polymers, including poly(methylmethacrylate) and poly(trifluoroethyl acrylate) containing two reactive OH groups at the polymer chain <2004MM6260>. 

Nair et al. studied the kinetics of the polymerization of MMA at 60-95 °C using N,1SP-diethyl-NjW-di(hydroxyethyl)thiuram disulfide (30a) as the thermal in-iferter [142]. The dependence of the iniferter concentration on the polymerization rate was examined. The chain transfer constant of the propagating radical of MMA to 30a was determined to be 0.23-0.46 at 60-95 °C, resulting in the activation energy of 37.6 kj/mol for the chain transfer. Other derivatives 30b-30d were also prepared and used to derive telechelic polymers with the terminal phosphorus, amino, and other functional aromatic groups [143-145]. Thermal polymerization was also investigated with the end-functional poly(St) and poly(MMA) which were prepared using the iniferter 13 [146]. 

Following route A (Fig. 1), Yan Xiao et al. reported the chemoenzymatic synthesis of poly(8-caprolactone) (PCL) and chiral poly(4-methyl-8-caprolactone) (PMCL) microparticles [5]. The telechelic polymer diol precursors were obtained by enzymatic polymerization of the corresponding monomers in the presence of hexanediol. Enzymatic kinetic resolution polymerization directly yielded the (R)-and (S )-enriched chiral polymers. After acrylation using acryloylchloride, the chiral and nonchiral particles were obtained by crosslinking in an oil-in-water emulsion photopolymerization. Preliminary degradation experiments showed that the stereoselectivity of CALB is retained in the degradation of the chiral microparticles (Fig. 2). 

Investigations were mainly devoted to the synthesis of telechelic polymers and copolymers rather than to living radical polymerization. In particular, from 1960, Imoto et al. [234] started surveys on the synthesis of block copolymers from this method. Thus, polystyrene-i>-poly(vinyl alcohol) diblock copolymer... 

Although several telechelic polymers of 1,3-dioxolane have been prepared by cationic polymerization, their application is limited due to their susceptibility to acid-catalyzed hydrolysis and/or depolymerization. By termination of living mono- and difunctional poly(l,3-dioxolane) with amines or phosphines, polymers containing one or two stable ionic (ammonium, phosphonium) end groups has been prepared [129,274],... 

The methods described above correspond to those attainable with conventional sol-gel chemistry. This strategy is simple, low cost, and yields amorphous hybrid materials, which can contain specific organic molecules, biocomponents or polyfunctional cross-linkable polymers (e.g., telechelic polymers). These materials exhibit an infinity of microstructures, can be transparent, and easily shaped as films or bulks (Fig. 2, Route A). However, they are generally poly-disperse in size and locally heterogenous in chemical composition. 

A variety of CEs with tailorable physico-chemical and thermo-mechanical properties have been synthesized by appropriate selection of the precursor phenol [39,40]. The physical characteristics like melting point and processing window, dielectric characteristics, environmental stability, and thermo-mechanical characteristics largely depend on the backbone structure. Several cyanate ester systems bearing elements such as P, S, F, Br, etc. have been reported [39-41,45-47]. Mainly three approaches can be seen. While dicyanate esters are based on simple diphenols, cyanate telechelics are derived from phenol telechelic polymers whose basic properties are dictated by the backbone structure. The terminal cyanate groups serve as crosslinking sites. The polycyanate esters are obtained by cyanation of polyhydric polymers which, in turn, are synthesized by suitable synthesis protocols. Thus, in addition to the bisphenol-based CEs, other types like cyanate esters of novolacs [37,48], polystyrene [49], resorcinol [36], tert-butyl, and cyano substituted phenols [50], poly cyanate esters with hydrophobic cycloaliphatic backbone [51], and allyl-functionalized cyanate esters [52] have been reported. 

Similarly, a telechelic polymer bearing carboxylic acid groups at both chain ends was formed by carrying out the lipase-catalyzed polymerization of DDL in the presence of divinyl sebacate [72]. In this case, divinyl sebacate functioned as a coupling agent creating poly(DDL) chains with hydroxyl groups at both termini. 

The use and limitations of Atom Transfer Radical Coupling (ATRC) reactions including polyrecombination reactions for the preparation of telechelic polymers, segmented block copolymers, and polycondensates are presented. Specifically, the preparation of telechelic polymers with hydroxyl, aldehyde, amino and carboxylic functionalities, poly(/i-xylylene) and its block copolymers, and polyesters via ATRC process is described. The method pertains to the generation of biradicals at high concentration from polymers prepared by ATRP or specially designed brfunctional ATRP initiators. The possibility of using silane radical atom abstraction (SRAA) reactions, that can be performed photochemically in the absence of metal catalysts, as an alternative process to ATRC is also discussed. 

Microwave irradiation Grafting onto method Various catalysts are used [4,4 -Azobis (4-cyanovaleric acid)] Telechelic polymers, polyethylene glycol, poly-dimethyl siloxane... 

End-group association in the melt can differ tremendously from that in solution. Binder s group recently investigated mixtures of polyisobutylenes (PIBs) and poly (butyl acrylates) containing thymine (Thy) and 2,6-diaminotriazines (DAT) end groups [58-60]. Thymine and DAT both self-associate however, they favor the formation of heterocomplementary complexes. Blends of monofunctional and telechelic polymers were systematically studied in solution and melt phases. 

Functionalized poly(vinyl ether)s can be prepared by the functionalized initiator method by the use of a HI/I2 initiating system and a functionalized vinyl ether, resulting in a-functionalized polymers. Carboxylic add- and amine-terminated polymers were prepared by this method with high degrees of functionality as determined by H NMR. This method can be extended to the preparation of telechelic polymers by quenching the polymerization with the appropriate nucleophile. Methacrylate-functionalized poly(vinyl ether) s... 

Figure 13 (a) Chemical structure of bi-UPy 18 and bi-NaPy 19 telechelic poly(octene) polymers prepared via ROMP, (b) Solution characterization of a supramolecular block copolymer double-logarithmic plot of specific viscosity as a function of concentration in chloroform for the 1 1 mix of bi-NaPy 19 telechelic polymer and the bi-UPy CTA used to prepare 18 (slope=3.48) and for the bi-NaPy 19 telechelic polymer alone, demonstrating the overlap concentration (slope = 1.68 and Z39 below and above the overlap concentration, respectively). Reproduced from Folmer, B. J. B. Sijbesma, R. P. ... 

Binder et al employed two different sets of complementary hydrogen-bonding motifs to cormect phase-separating poly(iso-butylene) and poly(etherketone) in the bulk. The telechelic polymers were synthesized with both sets of hydrogen-bond motifs appended to their respective chain ends, and all polymers were able to yield hydrogen-bonded block copolymers capable of microphase separation. The strongly botmd Hamilton receptor motif (Ka=3 X 1stabilized the material up to 230 ° C, beyond which macrophase separation was observed. 

Lonsdale, D. A. Monteiro, M. J., Kinetic Simulations for Cyclization of a,(0-Telechelic Polymers. J. Polym. Sci., Part A Polym. Chem. 2010,48,4496-4503. Clarson, S. J. Dodgson, K. Semiyen, J. A., Studies of Cyclic and Linear Poly(dimethylsiloxanes) 19. Glass Transition Temperatures and Crystallization Behaviour. Polymer 1985,26, 930-934. 

Typical examples are networks in aqueous solutions of polymers with short hydrophobic chains attached at both chain ends (telechelic polymers), such as hydrophobic poly(ethylene oxide), hydrophobic ethoxylated urethane (called HEUR) [1-5], hydrophobic poly(A -isopropylacrylamide) [6,7], poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) triblock copolymers [8-10], etc. These networks are analogous to the polymer networks whose elastic properties are studied in Chapter 4. They differ, however, in the important point that the network junctions can break and recombine. We extend the theoretical framework of rubber elasticity to suit for the study of polymer networks with temporal cross-link junctions. 

Another pathway yields a thermodynamically more stable product, but is kinetically less favorable. Because of extensive chain transfer the poljunerization of DXL is not living. However, if a fimctionalized acetal is added to the monomer, telechelic polymers, ega,op-bisacrylate ofpoly(DXL) (318), are obtained. Similarly, addition of trimethylamine to growing poly(DXL) initiated with triethyloxonium hexafluoroantimonate yields telechelics with one trimethylammonium and one ethoxy end group (319). 

Figure 12.8 Schematic representation of (a) step-growth coupling of bivalent azide and bivalent acetylene telechelic polymers (b) polymer modi cation by CuAAC of pendant alkyne groups of polymers, e.g., poly(vinyl acetylene), with an azide-bearing substrate and (c) functionalization of polymer by CuAAC of pendant azide with alkyne-bearing functional moiety. Azide terminated dendrimers are similarly subjected to CuAAC with alkyne-derivatized functional moieties to achieve desired functionalization of dendritic macromolecules.

Using the rst approach, Sumerhn and coworkers (Gondi et al., 2007) synthesized functional telechelic polymers for which two novel azido-functionalized chain trasfer agents (CTAs), namely, (Xn) and (XIII) (see Fig. 12.18), were prepared and employed to mediate the RAFT polymerization of styrene (St) and Af,Af-dimethylacrylamide (DMA) under a variety of conditions. Poly-... 

Discuss a possible method of synthesizing an asymmetric telechelic polymer based on poly(methyl methacrylate) (DP 50) with a carboxylic group at one end and a hydroxyl group at the other, using combined thiol-ene and CuAAC click reactions. 

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