Caprolactone diol polymer

Our group has recently reported on the preparation of PUR nanoparticles, based on poly(e-caprolactone) diol, 1,6-hexamethylene diisocyanate and aliphatic chain extenders, cyclohexanedimethanol and N-Boc serinol, for the encapsulation and release of the hydrophobic anti-cancer drug Paclitaxel (PX) and the anti-inflammatory drug Indomethacin (Mattu et al., 2013 Ferreira et al., 2014 Gentile et al., 2015a). Our studies showed the ability of PUR nanoparticles to encapsulate hydrophobic drugs and to extend their release as compared to commercial polymers. 

Zhou et al. described the synthesis of pH-sensitive biodegradable PUs. They used a novel pH-sensitive macrodiol containing acid-cleavable hydrazone linkers, poly(E-caprolactone)-hydrazone-poly(ethylene glycol)-hydiazone- ly(E-caprolactone) diol (PCL-Hyd-PEG-Hyd-PCL). The macrodiol was used with L-lysine ethyl ester diisocyanate (LDI) and L-lysine-derived tripeptide as chain extender [47]. These PUs could self-assemble into micelles in aqneons solutions. Later, the same research group synthesized pH-sensitive polymers nsing 1,4-bntanediol as chain extenders and suggested its use as antitumor drug carriers [41]. 

Into a three neck 250 mL flask equipped with a mechanical stirrer and a vacuum distillation head was added 0.11 m of 1,6-hexanediol (or 1,8-octanediol), 0.10 m L-tartaric acid, and 2% (w/w) SnCl2-21120 as catalyst. The mixture was heated under argon atmosphere to 120°C. After two hours, the pressure was reduced to 5-10 mm Hg. When the distillation of water was complete, the mixture was heated to 130 C and allowed to react for two more hours. The resulting crude polymer was dissolved in dioxane, precipitated from cold anhydrous ethyl ether, and dried in vacuo 48-72 hours. Poly(hexamethylene tartrate) was isolated as a clear elastomeric gum, while poly(octamethylene tartrate) was isolated as a dry white powder. Poly(caprolactone diol) or PCL was obtained commercially. 

Finally, Lecomte and coworkers reported the synthesis of mikto-arm star-shaped aliphatic polyesters by implementing a strategy based on click chemistry (Fig. 36) [162]. Firstly, the polymerization of sCL was initiated by a diol bearing an alkyne function. The chain-ends were protected from any further undesired reaction by the esterification reaction with acetyl chloride. The alkyne was then reacted with 3-azidopropan-l-ol. The hydroxyl function located at the middle of the chain was then used to initiate the ROP of sCL and y-bromo-s-caprolactone. Finally, pendant bromides were reacted successfully with sodium azide and then with N, N-dimethylprop-2-yn-l-amine to obtain pendant amines. Under acidic conditions, pendant amines were protonated and the polymer turned out to exhibit amphiphilic properties. 

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). 

This section describes a means to enhance the crystallization kinetics of absorbable polymers via polymer chemistry. It will show how this can be achieved by using an appropriate combination of mono- and difunctional alcohol initiators for ring-opening polymerization (ROP). Diols have been used commercially in ring-opening "prepolymerizations" to produce a,p-dihydroxy macroinitiators that are then used in a subsequent copolymerization to produce materials with special sequence distributions. This sequential addition ROP, in which a monomer feed portion is added in a subsequent step, is one method to make block copolyesters. An example is a glycolide/e-caprolactone copolymer that has enjoyed considerable commercial success. ... 

Lactide and y-caprolactone are copolymerized in the presence of a multifunctional polyol. For example, a diol such as ethylene glycol, may be included to produce a bifunctional hydroxyl terminated polymer, or a triol, such as trimethylolpropane, may be used to produce a trifunctional pol mier hydroxyl terminated polymer. 

SMPU containing polycarbonate segments were synthesized by the prepolymer method of an aliphatic polycarbonate diol. The macrodiol was synthesized by copolymerization of ethylene oxide in the presence of CO2 catalyzed by a polymer supported bimetallic catalyst [60]. In these polycarbonate urethanes Ttrans = 7g and was around 5 C. Another example with higher Ttrans are segmented polyesterurethanes based on a copolymer of L-lactide and e-caprolactone, providing the switching domains as well as the polyurethane from butanediol and 2,4-toluene diisocyanate [52]. Tsw could be adjusted between 28 and 53 °C. Rr was determined between 93 and 100%. 

Biodegradable shape-memory polymer networks with single POSS moieties located in the center of the network chains would promote POSS crystallization even within a constraining network structure. Successful synthesis of POSS initiated poly(e-caprolactone) (PCL) telechelic diols, utilizing a POSS diol as initiator, was reported by Lee et al. [116]. The POSS-PCL diols were terminated with acrylate groups and photocured in the presence of a tetrathiol crosslinker. Scheme 1 shows the chemical reaction for the synthesis of POSS-PCL network. 

In 2007, Cao and Jana at Akron tethered Cloisite 30B clay particles onto SMP polyurethanes [70]. The polyurethanes were synthesized from aromatic diisocyanates, a crystalline polyester polyol, and poly(e-caprolactone) (PCL) diol. The monomer ratios were cleverly balanced between an excess ratio of isocyanate in the polymer system and the pendant alcohol groups (-CH2CH2OH) on the quaternary ammonium ions fi om the Cloisite 30B. The team observed an increase in the rubbery modulus at 100°C (Tm-I- 50°C) of nearly one order of magnitude, from 4—5 MPa without loading to more than 20 MPa with loading. In the carefully crafted study, the authors determined that at high (5%) clay content, a more rapid relaxation of induced tensile stress reduces the recovery force of SMPs. In addition,... 

Poly(8-caprolactone) 1 is a simple, linear, aliphatic polyester formed by the ringopening addition polymerisation of 8-caprolactone, normally initiated by an alcohol or diol in the presence or absence of a catalyst. The polymer has a regular structure and is crystallisable. PCL crystallises to about 50% in the form of spherulites [10]. 

Ferreira et al. [75] synthesized a HMA for medical use. Urethanes based on polycaprolactone diol (PCL) were synthesized by reaction of the molecule either with isophorone diisocyanate (IPD-isocyanate) or hexamethylene diisocyanate (HDI-isocyanate). Nies Berthold et al. [76] tried out an adhesive composition based on polymers or polymer blends consisting of caprolactone copolymers or caprolactone copolymers and polycaprolactone. The adhesive can be utilized as HMA for temporarily gluing together biological tissue and other materials in medicine. 

Fig. 2.23 Representative plots of long-period against chain length, (a) Long-period against molecular weight for poly( -caprolactone) (From Ferret and Skoulios (69)). (b) Plot of long-period against the number of repeating units, , for a diol urethane polymer. (From Kern, Davidovits, Rauterkus and Schmidt (70))...

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