Polycaprolactone block copolymers

See also PBT degradation structure and properties of, 44-46 synthesis of, 106, 191 Polycaprolactam (PCA), 530, 541 Poly(e-caprolactone) (CAPA, PCL), 28, 42, 86. See also PCL degradation OH-terminated, 98-99 Polycaprolactones, 213 Poly(carbo[dimethyl]silane)s, 450, 451 Polycarbonate glycols, 207 Polycarbonate-polysulfone block copolymer, 360 Polycarbonates, 213 chemical structure of, 5 Polycarbosilanes, 450-456 Poly(chlorocarbosilanes), 454 Polycondensations, 57, 100 Poly(l,4-cyclohexylenedimethylene terephthalate) (PCT), 25 Polydimethyl siloxanes, 4 Poly(dioxanone) (PDO), 27 Poly (4,4 -dipheny lpheny lpho sphine oxide) (PAPO), 347 Polydispersity, 57 Polydispersity index, 444 Poly(D-lactic acid) (PDLA), 41 Poly(DL-lactic acid) (PDLLA), 42 Polyester amides, 18 Polyester-based networks, 58-60 Polyester carbonates, 18 Polyester-ether block copolymers, 20 Polyester-ethers, 26... 

Preparation and characteristics of ABA type polycaprolactone-b-polydimethyl-siloxane block copolymers have been recently reported 289). In this study, ring-opening polymerization of e-caprolactone was achieved in melt, using a hydroxybutyl terminated PSX as the initiator and a catalytic amount of stannous octoate. Reactions were completed in two steps as shown in Reaction Scheme XIX. 

Figure 6.6 Reactive extrusion block copolymer of poly(ethylene terephthalate) and polycaprolactone...

Nanospheres of PEC-Polycaprolactone A-B Block Copolymer as a Novel Drug Carrier... 

Xiong, X.Y., Tam, K.C. and Gan, L.H., 2006. Synthesis and thermally responsive properties of novel Pluronic F87/polycaprolactone (PCL) block copolymers with short PCL blocks. Journal of Applied Polymer Science, 100(5), 4163—4172. 

Gong, CY Qian, ZY Liu, CB Huang, MJ Gu, YC Wen, YJ et al. A Thermosensitive Hydrogel Based on Biodegradable Amphiphilic Poly(ethylene glycol)-polycaprolactone-poly(ethylene glycol) block Copolymers. Smart Mater Struct, 2007, 16,927-933. 

PHA chemical modification can be done via block copolymerizadon and grafting reactions, chlorination, cross-linking, epoxidation, hydroxyl and carboxylic acid functionalization, etc. (Chen et al. 2009 Wu et al. 2008 Li et al. 2003 Loh et al. 2007). A common approach to confer toughness to PLA is the use of a flexible monomer or macromolecules for copolymerization with lactide to form PLA-based random or block copolymers. Reported PLA-based block copolymers include diblock, triblock, and multiblock copolymers, such as poly(L-lactic acid) (PLLA)-polycaprolactone (Jeon et al. 2003), poly(ethylene glycol)-PLLA (Chen et al. 2003), poly(trimethylene carbonate)-PLLA (Tohru et al. 2003), and PLA-PBS-PLA. 

In a similar manner, Yoshida and Osagawa [436] synthesized poly(s-caprolactone) with 2,2,6,6-tetramethylpiperdine-l-oxyl (TEMPO) at one end by anionic polymerization of caprolactone using an aluminum tri(4-oxy-TEMPO) initiator. The TEMPO-supported polycaprolactone behaved as a polymeric counter radical for a controlled/ living radical polymerization of styrene to form block copolymers [436]. 

Degradable elastomeric block copolymers based on polycaprolactone by free-radical chemistry. Macromol Chem. Phys., 212, 1327. 

Chemistry Polyurethane is produced by the reaction of a polyol with an diisocyanate (or in some instances a polyisocyanate) in the presence of catalysts. The polyols of choice are poly(propylene glycol), block copolymers of ethylene oxide (10-15%) with propylene oxide, or the newer polymer polyols (based on polymers such as polystyrene or styrene-acrylonitrile copolymer). Polyester diols such as polycaprolactone diol can be used in place of the polyether polyol in this reaction. The isocyanate of choice is a mixture of the 2,4 and 2,6 isomers of tolylene di-isocyanate in the ratio of 80 20, generally referred to as 80 20TDI. Other isocyanates such as diphenylmethane di-isocyanate (MDI), hexamethylene di-isocyanate (HMDI), and isophorone di-isocyanate (IPDI) are also used. A tin-based or amine catalyst is used to promote the reaction. Given the wide choice of reactants available, the reaction can yield foams with a range of different mechanical and thermal characteristics. 

Common SS include polyethers, polyesters and polyalkyl glycols with glass transition temperatures in the range of -70°to -30°C. Commonly used macrodiols in the PUs synthesis are polyalkyl-diols, such as polyisobutylene diol [70], polybutadiene (PBU) [20, 71], or oligo-butadiene diols [72] as well as hydrogenated polybutadiene diol [20] polyether diols polytetrahydrofuran (PTHF or PTMO) [50-52], polyethylene glycol (PEG) or (PEO) [73], polypropyleneoxide (PPO) [73] or mixed blocks of them PEO-PPO-PEO [74] and PPO-THF [54] polyester diols poly(ethylene adipate) (PEA) [4,20], poly(butylene adipate) (PBA) [20, 73], and latterly polycaprolactone diol (PCL or PCD) [75], polyalkylcarbonate polyol [20] or mixed blocks of them, for example poly(carbonate-co-ester)diol [76], poly(hexamethylene-carbonate)diol [77], as well as poly(hexamethylene-carbonate-co-caprolactone)diol [78] and a mixed block copolymer of polyether and polyester blocks PCL-b-PTHF-b-PCL [79]. Examples schemes of macrodiols are shown in Eig. 1.9. 

As polyurethane intermediates react rapidly and stoichiometrically with each other, a system of nomenclature is widely used to describe the structure of individual block copolymers. Suppose, for example, a typical polyurethane consisted of polycaprolactone,4,4 -diphenylmethane diisocyanate, and 1,4-butane diol, present in the molar ratio 1 3 2, then such a polymer is reported as a 1 3 2 block copolymer and this represents a simple, convenient and rapid method of identifying the basic urethane polymer structure. The ratio of each component in the block copolymer has a dramatic effect on its properties, as shown by the data in Table 2.2. 

In terms of pharmaceutical applications, copolymers have been used as drug carriers for controlled release applications. Controlled release polymer vesicles are prepared using hydrolysable block copolymers such as PLAEG, which is poly-lactic acid co-polyethylene glycol, PLAEG (ie, polycaprolactone-co-polyethylene glycol). 

Figure 9 Top cartoon representations of a spherical micelle, a wormlike micelle, and a vesicle. The red blocks represent the solvophilic blocks, and the blue blocks represent the solvophobic blocks. Bottom example TEM images showing diffa-ent micelle morphologies adopted by block copolymers in solution, (a) Spherical micelles formed from polyfethylene oxide)-f>-polycaprolactone (PEO-f>-PCL) copolymers.(b) Wormlike micelles, vesicles, and octupi formed by mixing PEO-fc-polybutadiene (PEO-fc-PB) block copolymers. (Reproduced from Ref. 32. American Chemical Society, 2004.) (c) Vesicles formed from PEO-f>-PCL copolymers. (Reproduced from Ref. 33. Royal Society of Chemistry, 2011.) (d) Multicompartment micelles formed from a triblock copolyma-. (Reproduced from Ref. 34. American Chemical Society, 2010.) (e) Stomatocytes formed using PEO-f>-polystyrene (PEO-f>-PS) copolyma-s. (Reproduced from Ref. 35. American Chemical Society, 2010.) (f) Toroidal micelles coexisting with cylindrical micelles and sphaical micelles formed from poly(acrylic acid)-f>-poly(methacrylic acid)-fc-PS (PAA-f>-PMA-f>-PS) triblock copolymers. (Reproduced from Ref. 36. Royal Society of Chemistry, 2009.)...

PLA), and PEO-PCL (polycaprolactone). Self-assembly of block copolymers readily form nano- or microsized poly-mersomes, but large polymersomes can be sonicated or extruded through nanoporous filters to obtain nanopoly-mersomes or nanocapsules. The process was reviewed by Antonietti and FOrster. ... 

Li Z, Li J. Control of hyperbranched structure of polycaprolactone/poly(ethylene glycol) polyurethane block copolymers by glycerol and their hydrogels for potential cell delivery. J Phys Chem B 2013 117(47) 14763-74. 

Chen, D., et al. Morphology and biodegradation of microspheres of polyester-polyether block copolymer based on polycaprolactone/polylactide/ polyfethylene oxide). Polymer International, 49(3) p. 269. 2000. 

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