Ring-opening Polymerization Of CL Research Articles

High‐efficiency shape memory copolymers of polycaprolactone/thermoplastic polyurethane fabricated via in situ ring‐opening polymerization

AbstractShape memory blends of polycaprolactone/thermoplastic polyurethane (PCL/TPU) were prepared by in situ ring‐opening polymerization (ROP) of ε‐caprolactone (CL) and thermoplastic polyurethane (TPU). Fourier infrared spectrometer and 1H‐NMR were used to characterize the chemical structure of PCL/TPU copolymers. The results show that TPU has been involved in the ROP of CL, leading to the formation of copolymers with homogeneous morphologies. Besides, pure PCL and all the blends exhibit an excellent shape fixation ratio of 100%, due to their high crystallinity. When a small amount of TPU is introduced, the crystallinity of PCL decreases, and as a result, the shape recovery ratio of the copolymer is enhanced compared with pure PCL. However, with the increased loading of TPU, the content of PCL as the reversible phase decreases and the storage modulus of the PCL/TPU blend declines, so the driving force for the blends to return from the temporary shape to the initial shape becomes smaller, leading to a decrease in the shape recovery ratio. Notably, when the amount of TPU is only 5%, the shape recovery ratio of the blend could reach 83.3%, which is 26% higher than that of pure PCL, and meanwhile, the tensile strength of the blend decreases slightly. This study provides a new strategy for the design of shape‐memory materials with high shape‐memory properties.

Molecular Brushes with a Polyimide Backbone and Poly(ε-Caprolactone) Side Chains by the Combination of ATRP, ROP, and CuAAC.

An approach to the synthesis of the novel molecular brushes with a polyimide (PI) backbone and poly(ε-caprolactone) (PCL) side chains was developed. To obtain such copolymers, a combination of various synthesis methods was used, including polycondensation, atom transfer radical polymerization (ATRP), ring opening polymerization (ROP), and Cu (I)-catalyzed azide-alkyne Huisgen cycloaddition (CuAAC). ATRP of 2-hydroxyethyl methacrylate (HEMA) on PI macroinitiator followed by ROP of ε-caprolactone (CL) provided a “brush on brush” structure PI-g-(PHEMA-g-PCL). For the synthesis of PI-g-PCL two synthetic routes combining ROP and CuAAC were compared: (1) polymer-analogous transformations of a multicenter PI macroinitiator with an initiating hydroxyl group separated from the main chain by a triazole ring followed by ROP of CL, or (2) a separate synthesis of macromonomers with the desirable functional groups (polyimide with azide groups and PCL with terminal alkyne groups), followed by a click reaction. Results showed that the first approach allows to obtain graft copolymers with a PI backbone and relatively short PCL side chains. While the implementation of the second approach leads to a more significant increase in the molecular weight, but unreacted linear PCL remains in the system. Obtained macroinitiators and copolymers were characterized using 1H NMR and IR spectroscopy, their molecular weight characteristics were determined by SEC with triple detection. TGA and DSC were used to determine their thermal properties. X-ray scattering data showed that the introduction of a polyimide block into the polycaprolactone matrix did not change the degree of crystallinity of PCL.

Polycaprolactone/Graphene Nanocomposites: Synthesis, Characterization and Mechanical Properties of Electrospun Nanofibers

In this study, three polymer nanocomposites based on poly(e-caprolactone) (PCL) grafted on the graphene quantum dot (GQD), hydroxypropyl cellulose (HPC)/GQD (GQD: HPC = 1:1; w/w) and graphene oxide (GO) with 1.6 wt% of e-caprolactone (CL) were synthesized via in situ ring opening polymerization of CL. The synthesized nanocomposites were characterized using FTIR, 1H NMR, and contact angle measurements. The lowest molecular weight for PCL/GO was obtained according to 1H NMR spectra. Crystalline structure and thermal behavior of composites were investigated by XRD, DSC and TGA. The results showed that the presence of HPC and graphene-based nanofillers in nanocomposite can affect the hydrogen bonding interaction with PCL chains, melting temperature (Tm), degree of crystallinity [Xc(%)] and the size of crystals. According to the results, PCL/GQD-HPC had higher Tm, lower Xc(%), longer PCL moieties and smaller crystals. Also, the TGA results indicated that the nanocomposites were thermally more stable than the pure PCL. Moreover, a conventional electrospinning process was used to prepare nanofibers of synthesized nanocomposites blended with PCL (50:50; w/w). SEM images and mechanical behavior study of obtained nanofibers depicted that the PCL/(PCL/GQD-HPC) nanofibers have a significant increment in the average diameter, tensile modulus and strength in comparison with other composites.

A systematic study of macrodiols and poly(ester-urethanes) derived from α,ω-hydroxy telechelic poly(ε-caprolactone) (HOPCLOH) with different ether [CH2CH2O]m groups. Synthesis and characterization

α,ω-Hydroxy telechelic poly(e-caprolactone) (HOPCLOH) was synthesized by ring-opening polymerization (ROP) of e-caprolactone (e-CL).The ROP was catalyzed by ammonium decamolybdate in the presence of ether diols [HO-(CH2-CH2-O)m-H] (where m = 2, 3, 4, 5, 6, and 8) as initiators. The homopolymer HOPCLOH was obtained with the ether group (EG) [HO-PCL-(CH2-CH2-O)m-PCL-OH (HOPCLOH)] as part of the backbone of the polyester with a systematic increase in the segment of the EG. The number average molecular weight (Mn) for all samples were similar in the range of oligomers (Mn = 1240–1510 Da) to have a significant effect of the EG. The effect of the EG on the physical properties was evaluated by differential scanning calorimetry (DSC) where the crystallinity of HOPCLOH and the size of the EG showed a relationship inversely proportional. Poly(ester-urethanes) (PEUs) derived from HOPCLOH exhibited an elastomeric behavior, where long chains of EG induced poor mechanical properties. The use and selection of the ether diols as initiators in the ROP of CL to synthesize HOPCLOH was not trivial because these EG substituents affected the crystallinity, and the mechanical properties of their PEUs.

Synthesis and characterization of a novel amphiphilic poly (ethylene glycol)–poly (ε-caprolactone) graft copolymers

A series of amphiphilic graft copolymers PEO-g-PCL with different poly (ε-caprolactone) (PCL) molecular weight were successfully synthesized by a combination of anionic ring-opening polymerization (AROP) and coordination-insertion ring-opening polymerization. The linear PEO was produced by AROP of ethylene oxide (EO) and ethoxyethyl glycidyl ether initiated by 2-(2-methoxyethoxy) ethoxide potassium, and the hydroxyl groups on the backbone were deprotected after hydrolysis. The ring-opening polymerization of CL was initiated using the linear poly (ethylene oxide) (PEO) with hydroxyl group on repeated monomer as macroinitiator and Sn(Oct)2 as catalyst, then amphiphilic graft copolymers PEO-g-PCL were obtained. By changing the ratio of monomer and macroinitiator, a series of PEO-g-PCL with well-defined structure, molecular weight control, and narrow molecular weight distribution were prepared. The expected intermediates and final products were confirmed by 1H NMR and GPC analyzes. In addition, these amphiphilic graft copolymers could form spherical aggregates in aqueous solution by self-assemble, which were characterized by transmission electron microscopy, and the critical micelle concentration values of graft copolymers PEO-g-PCL were also examined in this article.

Synthesis, characterization, catalytic and splinting activity of nano Ag end capped l‐glutathione bridged amphiphilic diblock copolymer

ABSTRACTl‐glutathione, a naturally occurring environmental friendly amino acid, was used as an initiator towards the ring opening polymerization (ROP) of ɛ‐caprolactone (CL) followed by the ROP of tetrahydrofuran (THF). The thiol group of l‐glutathione reduces Ag+ ions and chemically bound to the surface of Ag nanoparticles. The ROP of CL was carried out at 160 °C under nitrogen atmosphere in the presence of stannous octoate(SO) as catalyst whereas the ROP of THF was carried out at 45 °C for 24 h in the presence of phthalic anhydride (PAH) as a comonomer. The synthesized homo, di and nano Ag end capped diblock copolymers were characterized by FTIR, DSC, TGA, FESEM, high resolution transmission electron microscope (HRTEM), EDAX, GPC, nuclear magnetic resonance (NMR), Fluorescence and CD. Further the application of diblock copolymer was tested for splinting activity. The catalytic reduction of 4‐nitrophenol (NP) in the presence of nano Ag end capped diblock copolymer was carried out with the assistance of sodium borohydride as a reducing agent and the apparent rate constant (kapp) was determined and compared with the literature values. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43804.

Synthesis and characterization of novel fluorescent amphiphilic diblock copolymer

In the present study, an amphiphilic diblock copolymer made of poly(e-caprolactone) (PCL) and poly(tetrahydrofuran) (PTHF) was synthesized via ring opening polymerization (ROP) of e-caprolactone (CL) and tetrahydrofuran (THF) with rose bengal (RB) as a bridging agent in a two-step process. In the first step, RB–PCL was synthesized by the ROP of CL, while in the second step the diblock copolymer was prepared by the ROP of THF with RB–PCL moiety as a chemical initiator in the presence of phthalic anhydride (PAH) as a co-monomer. The diblock copolymer was characterized by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infra red (FTIR) spectroscopy, UV–visible spectroscopy, fluorescence spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), gel permeation chromatography (GPC) and EDX studies.

In vitro enzymatic degradation of the cross-linked poly(ε-caprolactone) implants

The cross-linked poly(ε-caprolactone) (PCL) implants were directly prepared via the ring-opening polymerization of CL with cross-linker (BTB). The in vitro enzymatic degradation of the resulting implants was performed with Thermomyces lanuginosus lipase. We saw that the cross-linked PCL implants degraded in lipase via the surface erosion mechanism. The higher the molar ratio of monomers to catalyst or the higher the cross-linker amount in feeding dose, the slower the degradation rate of the cross-linked PCL implants. Moreover, the degradation rate of the cross-linked PCL implants was lower than that of the uncross-linked ones, which could markedly reduce the acidic degradation products. The macroscopic observation results indicated that the cross-linked PCL implants had good form-stability. The changes in thermal properties showed that the degradation occurred in both amorphous and crystalline regions. The results implied that the highly cross-linked PCL implants had great potential as controlled drug release agents.

Effects of alkoxide alteration on the ring-opening polymerization of ε-caprolactone initiated by n-Bu3SnOR: a DFT study

The ring-opening polymerization (ROP) of e-caprolactone (CL) initiated by tributyltin alkoxides (n-Bu3SnOR), where R = methyl (Me), ethyl (Et), propyl (Pr), and butyl (Bu), was investigated using density functional theory at B3LYP level with mixed basis set. A coordination–insertion mechanism with two transition states was found for all ROP reactions: (1) starting with a coordination of CL onto Sn center led to a nucleophilic addition of the carbonyl group of CL, (2) followed by the exchange of alkoxide ligand with Sn atom and the ROP of CL was completed through classical acyl-oxygen bond cleavage. The barrier heights of all reactions with different initiators were calculated using potential energy profiles. All ROP reactions initiated with n-Bu3SnOR demonstrated exothermic reaction and the rate-determining step was the first transition state. The ROP of CL with n-Bu3SnOMe has the smallest value of barrier height compared to other reactions. Moreover, the activation energies for all ROP reactions, calculated using the transition state theory with TheRATE program, are in good agreement with available experimental data.

Synthesis, characterization and catalytic activity of Ag-acidfuchsin nanohybrid system towards the ring opening polymerization of ε-caprolactone

The acidfuchsin (AF) decorated Ag nanoparticle (NP) was synthesized and its ability towards the ring opening polymerization (ROP) of ε-caprolactone (CL) was studied under N2 atmosphere at 160°C in the presence of stannous octoate (SO) as a catalyst. Both the nanohybrid and nanocomposites were characterized by various analytical tools like Fourier transform infrared (FTIR) spectroscopy, UV–visible spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, fluorescence spectroscopy, gel permeation chromatography (GPC), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The number of binding site from the fluorescence spectrum confirmed that all the functional groups present in AF might have been involved in the ROP of CL.

Synthesis of poly(N-isopropylacrylamide)-b-poly(ɛ-caprolactone) and its inclusion compound of β-cyclodextrin

Well-defined amphiphilic poly(N-isopropylacrylamide)-b-poly(ɛ-caprolactone) (PNIPAM-b-PCL) block copolymers have been successfully prepared in two steps. PNIPAMOH is firstly prepared by using 4,4′-azobis(4-cyano-1-pentanol) as bifunctional initiator, and then PNIPAM-b-PCL copolymer is synthesized via a ring-opening polymerization of CL using PNIPAMOH as a macro-initiator in the presence of stannous octoate as a catalyst. The PNIPAM-b-PCL copolymers self-assemble to form spherical micelles of 50–130nm in diameter, which can be modulated by the chain length of PCL block. The inclusion complexes are fabricated by treating PNIPAM-b-PCL with β-cyclodextrin and they are characterized by infrared and 1H NMR spectroscopies, X-ray powder diffraction, thermogravimetric analysis, and differential scanning calorimetry.

Synthesis, characterization and band gap energy of poly(ε-caprolactone)/Sr-MSA nano-composite

A mercaptosuccinic acid (MSA) decorated Sr nano-particle (NP) was prepared and characterized by using various analytical techniques and was used as a chemical initiator for the ring opening polymerization (ROP) of ε-caprolactone (CL). The ROP of CL was carried out at various experimental conditions under N2 atmosphere with mild stirring. The initiating efficiency of MSA-decorated Sr NP was tested in terms of Fourier transform infrared-relative intensity, melting temperature (Tm), degradation temperature (Td) and molecular weight (Mw) of poly(ε-caprolactone) (PCL), differential scanning calorimetry, UV–visible spectroscopy, field emission scanning electron microscopy, thermogravimetric analysis and gel permeation chromatography analytical techniques. The nuclear magnetic resonance spectrum confirms the chemical structure of PCL. While increasing the [M/I] ratio, the Mw of PCL was linearly increased. The band gap energy of Sr was determined from the UV–visible spectrum. The reflectance study proves the hydrophobic nature of the Sr-hybrid and its nano-composite formation with PCL.

Poly(<i>Ethylene Oxide</i>)-B-Poly(<i>ε-Caprolactone</i>) Amphiphilic Block Copolymers: Synthesis and Self-Assembly

A series of amphiphilic block copolymers mPEO-b-PCL with different PCL molecular weight were successfully prepared by combination of anionic ring-opening polymerization with coordination-insertion ring-opening polymerization. Firstly, the linear mPEO was prepared by anionic ring-opening copolymerization of EO with 2-(2-methoxyethoxy) ethoxide potassium as the small molecule initiators, then the mPEO as the macroinitiator was used to initiate the ring-opening polymerization of CL, in the absence of Sn(Oct)2 as the catalyst, and amphiphilic block copolymers mPEO-b-PCL were obtained. By changing the ratio of monomer and macroinitiator, prepared a series of different molecular weight mPEO-b-PCL. The structure of intermediates and final products were characterized by 1H NMR and GPC. The critical micelle concentration (cmc) of the final copolymer was measured. In addition, the sizes and morphologies of the obtained micelles at different PCL chains were studied with Laser nano-particle size analyzer and transmission electron microscopy (TEM).

Fine Tuning Micellar Core-Forming Block of Poly(ethylene glycol)-block-poly(ε-caprolactone) Amphiphilic Copolymers Based on Chemical Modification for the Solubilization and Delivery of Doxorubicin

This study aimed to optimize poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-b-PCL)-based amphiphilic block copolymers for achieving a better micellar drug delivery system (DDS) with improved solubilization and delivery of doxorubicin (DOX). First, the Flory-Huggins interaction parameters between DOX and the core-forming segments [i.e., poly(ε-caprolactone) (PCL) and poly[(ε-caprolactone-co-γ-(carbamic acid benzyl ester)-ε-caprolactone] (P(CL-co-CABCL))] was calculated to assess the drug-polymer compatibility. The results indicated a better compatibility between DOX and P(CL-co-CABCL) than that between DOX and PCL, motivating the synthesis of monomethoxy-poly(ethylene glycol)-b-poly[(ε-caprolactone-co-γ-(carbamic acid benzyl ester)-ε-caprolactone] (mPEG-b-P(CL-co-CABCL)) block copolymer. Second, two novel block copolymers of mPEG-b-P(CL-co-CABCL) with different compositions were prepared via ring-opening polymerization of CL and CABCL using mPEG as a macroinitiator and characterized by (1)H NMR, FT-IR, GPC, WAXD, and DSC techniques. It was found that the introduction of CABCL decreased the crystallinity of mPEG-b-PCL copolymer. Micellar formation of the copolymers in aqueous solution was investigated with fluorescence spectroscopy, DLS and TEM. mPEG-b-P(CL-co-CABCL) copolymers had a lower critical micelle concentration (CMC) than mPEG-b-PCL and subsequently led to an improved stability of prepared micelles. Furthermore, both higher loading capacity and slower in vitro release of DOX were observed for micelles of copolymers with increased content of CABCL, attributed to both improved drug-core compatibility and favorable amorphous core structure. Meanwhile, DOX-loaded micelles facilitated better uptake of DOX by HepG2 cells and were mainly retained in the cytosol, whereas free DOX accumulated more in the nuclei. However, possibly because of the slower intracellular release of DOX, DOX-loaded micelles were less potent in inhibiting cell proliferation than free DOX in vitro. Taken together, the introduction of CABCL in the core-forming block of mPEG-b-PCL resulted in micelles with superior properties, which hold great promise for drug delivery applications.

Conversion of sulfuric acid lignin generated during bioethanol production from lignocellulosic materials into polyesters with ɛ-caprolactone

In this study, polyesters were prepared from sulfuric acid lignin (SAL) that was generated as a by-product during the production of bioethanol from lignocellulosic materials using ɛ-caprolactone (CL). Carboxylic groups were introduced into SAL by a hydrothermal reaction under alkali conditions. The acid form (-COOH) of the obtained polymer (HSAL) was dissolved into ɛ-caprolactone and the mixture was heated at 150°C for 12 h with ZnCl2 as a catalyst. The structure of the obtained polymer (PCL-HSAL) was proposed based on results of differential scanning calorimetric analysis, swelling tests, and dynamic mechanical thermal analysis. The hydroxyl group in HSAL participated in the ring-opening polymerization of CL. PCL-HSAL with a high HSAL content formed a three-dimensional network that did not dissolve in organic solvents and did not melt at high temperature. PCL-HSAL showed a high swelling property for a suitable ratio of CL to HSAL.

Synthesis of Biodegradable Amphiphilic Y-shaped Block Co-polymers via Ring-Opening Polymerization for Drug Delivery

A series of novel Y-shaped biodegradable block co-polymers of poly(ε-caprolactone) (PCL) and poly(ethyl ethylene phosphate) (PEEP) (PCL–(PEEP)2) were synthesized via ring-opening polymerization (ROP) of EEP with bis-hydroxy-functional ROP initiator (init–PCL–(OH)2). The init–PCL–(OH)2 was synthesized by ROP of CL using 4-hydroxybutyl acrylate (HBA) as initiator and L-tartaric acid as catalyst in bulk, and subsequently the resulting vinyl-terminated PCL was end-capped by acetyl chloride, followed by Michael addition using excess diethanolamine. The Y-shaped co-polymers and their intermediates were characterized by 1H-, 13C-, 31P-NMR, FT-IR and gel-permeation chromatography. The results indicated that the molecular weight of the Y-shaped co-polymers increased with the increasing of the molar ratios of EEP to init–PCL–(OH)2 in the feed, while the PCL chain length was kept constant. The amphiphilic block co-polymers could self-assemble into micelles in aqueous solution, which was demonstrated by dynamic light scattering, 1H-NMR and atomic force microscopy. A study of controlled release of indomethacin indicated that the amphiphilic block co-polymers could potentially provide novel vehicles for drug delivery.

Synthesis and characterization of amphiphilic poly(N‐vinyl pyrrolidone)‐b‐poly(ε‐caprolactone) copolymers by a combination of cobalt‐mediated radical polymerization and ring‐opening polymerization

AbstractAn amphiphilic block copolymer of poly(N‐vinyl pyrrolidone)‐b‐poly(ε‐caprolactone) (PVP‐b‐PCL) was synthesized by a combination of cobalt‐mediated radical polymerization (CMRP) and ring‐opening polymerization (ROP). The micellar characteristics of this copolymer were subsequently investigated. PVP (Mn = 11,400, Mw/Mn = 1.32) was synthesized at 20 °C via CMRP using a molar ratio of [VP]0/[V‐70]0/[Co]0 = 150/8/1. The PVP was then reacted with 2,2′‐azobis[2‐methyl‐N‐(2‐hydroxyethyl)propionamide] (VA‐086) to modify its cobalt complex chain end to a hydroxyl group. The cobalt (Co) content in the resulting PVP‐OH was 1.2 ppm, indicating that all of the covalent CoC bonds were cleaved and reacted with VA‐086, and that the separated cobalt complexes were successfully removed. The ROP of CL was subsequently carried out using the produced PVP‐OH as a macroinitiator at 110 °C. The GPC trace of PVP‐b‐PCL was monomodal without any tailing caused by the residual PVP‐OH, indicating that the initiation efficiency was very high. The critical micelle concentration (CMC) of PVP‐b‐PCL (Mn = 18,000, Mw/Mn = 1.35) was 0.015 mg/mL. The PVP‐b‐PCL micelles were spherical in shape with an average diameter of 105 nm. The nanosized PVP‐b‐PCL micelles show promise as novel drug carriers in biomedical and pharmaceutical applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3078–3085, 2009

Enzymatic Preparation of Novel Thermoplastic di-Block Copolyesters Containing Poly[(R)-3-hydroxybutyrate] and Poly(ϵ-Caprolactone) Blocks via Ring-Opening Polymerization

Enzymatic modification of a microbial polyester was achieved by the ring-opening polymerization of epsilon-caprolactone (CL) with low-molecular weight telechelic hydroxylated poly[( R)-3-hydroxybutyrate] (PHB-diol) as initiator and Novozym 435 (immobilized Candida antarctica Lipase B) as catalyst in anhydrous 1,4-dioxane or toluene. The ring-opening polymerization was investigated at different conditions with two different types of PHB-diols: PHB-diol(P), containing a primary OH and a secondary OH end groups, and PHB-diol(M), consisting of 91% PHB-diol(P) and 9% PHB-diol containing two secondary OH end groups. The reactions were followed by GPC analyses of the resulting polymers at different time points, and the optimal conditions were established to be 70 degrees C at a weight ratio of CL/enzyme/solvent of 8:1:24. The ring-opening polymerization of CL with PHB-diol(M) (Mn of 2380, NMR) at the molar ratio of 50:1 under the optimal conditions in 1,4-dioxane gave the corresponding poly[HB(56 wt %)-co-CL(44 wt %)] with Mn (NMR) of 3900 in 66% yield. Polymerization of CL and PHB-diol(P) ( Mn of 2010, NMR) at the same condition in toluene gave the corresponding poly[HB(28 wt %)-co-CL(72 wt %)] with Mn (NMR) of 7100 in 86% yield. Both polymers were characterized by (1)H and (13)C NMR and IR analyses as di-block copolyesters containing a PHB block with a secondary OH end group and a poly(epsilon-caprolactone) (PCL) block with a primary OH end group. NMR analyses and control experiments suggested no formation of random copolymers and no change of the PHB block during the reaction. The enzymatic ring-opening polymerization was selectively initiated by the primary OH group of PHB-diol, whereas the secondary OH group remained as an end group in the final polymers. The thermal properties of the di-block poly(HB-co-CL)s were analyzed by DSC, with excellent T g values for the elastomer domain: poly[HB(56 wt %)- co-CL(44 wt %)] with M n (NMR) of 3900 demonstrated a T g of -57 degrees C, Tm of 145, 123, and 53 degrees C; and poly[HB(28wt%)-co-CL(72wt%)] with Mn (NMR) of 7100 gave a Tg of -60 degrees C, Tm of 147 and 50 degrees C. Thus, the selective enzymatic ring-opening polymerization with PHB-diol as macro-initiator provides a new method for the preparation of PHB-based block copolymers as biomaterials with good thermoplastic properties and novel structures containing functional end groups.

Ring-opening polymerization of ɛ-caprolactone by base catalyst for synthesis of grafted polysilsesquioxane

The polysilsesquioxane having amino and phenyl groups (APSQ) was prepared from the corresponding trimethoxysilanes by co-condensation under basic conditions. The amino group on APSQ was utilized as an initiator for graft polymerization of ɛ-caprolactone (CL). The ring-opening polymerization of CL, in the presence of a catalytic amount of the base prepared from triazabicyclodecene, proceeded effectively to afford the polysilsesquioxane having poly(CL) as the graft chains (GrPSQ). In the grafting, no formation of cross-linked product was observed. The grafted poly(CL) component in GrPSQ showed improved durability for heat as an advantage of the hybrid polymer containing polysiloxane structure.

Synthesis and crystallization behaviors of poly(styrene- b-isoprene- b- ε-caprolactone) triblock copolymers

The triblock copolymers, poly(styrene- b-isoprene- b- ε-caprolactone)s (PS- b-PI- b-PCL) have been synthesized successfully by combination of anionic polymerization and ring-opening polymerization. Diblock copolymer capped with hydroxyl group, PS- b-PI-OH was synthesized by sequential anionic polymerization of styrene and isoprene and following end-capping reaction of EO, and then it was used as macro initiator in the ring-opening polymerization of CL. The results of DSC and WAXD show big effect of amorphous PS- b-PI on the thermal behaviors of PCL block in the triblock copolymers and the lower degree of crystalline in the triblock copolymer with higher molecular weight of PS- b-PI was observed. The real-time observation on the polarized optical microscopy shows the spherulite growth rates of PCL 27, PCL 328 and PS- b-PI- b-PCL 344 are 0.71, 0.46 and 0.07 μm s −1, respectively. The atomic force microscopy (AFM) images of the PS 90- b-PI 66- b-PCL 28 show the columns morphology formed by it’s self-assembling.