PCL Arms Research Articles

From Facile One-Pot Synthesis of Semi-Degradable Amphiphilic Miktoarm Polymers to Unique Degradation Properties.

We report a one-pot synthesis of well-defined A5B and A8B miktoarm star-shaped polymers where N,N-dimethylaminoethyl methacrylate (DMAEMA) and various cyclic esters such as ε-caprolactone (ε-CL), lactide (LA) and glycolide (GA) were used for the synthesis. Miktopolymers were obtained by simultaneously carrying out atom transfer radical polymerization (ATRP) of DMAEMA, ring-opening polymerization (ROP) of cyclic esters, and click reaction between the azide group in gluconamide-based (GLBr5-Az) or lactonamide-based (GLBr8-Az) ATRP initiators and 4-pentyn-1-ol. The relatively low dispersity indices of the obtained miktoarm stars (Đ = 1.2-1.6) indicate that control over the polymerization processes was sustained despite almost complete monomers conversions (83-99%). The presence of salts from phosphate-buffered saline (PBS) in polymer solutions affects the phase transition, increasing cloud point temperatures (TCP) values. The critical aggregation concentration (CAC) values increased with a decreasing number of average molecular weights of the hydrophobic fraction. Hydrolytic degradation studies revealed that the highest reduction of molecular weight was observed for polymers with PCL and PLGCL arm. The influence of the composition on the miktopolymers hydrophilicity was investigated via water contact angle (WCA) measurement. Thermogravimetric analysis (TGA) disclosed that the number of arms and their composition in the miktopolymer affects its weight loss under the influence of temperature.

Benzimidazolium ionic liquid functionalized star-polycaprolactone stationary phase for capillary gas chromatography

In this work, an innovative ionic liquid functionalized star-shaped polymer is synthesized by coupling star-polycaprolactone with benzimidazolium (star-PCL-Bim), and statically coated into a capillary column for gas chromatographic (GC) separations. The fabricated star-PCL-Bim capillary column with moderate-polar nature reveals a high column efficiency of 3598 plates/m for n-dodecane at 120 °C, and advantageous distinguishing ability ( R > 1.5) for 9 aromatic isomer mixtures and 12 cis-/ trans -isomers. Its excellent resolving capacity can be credited to the architecture of star-PCL-Bim, the PCL arms, and π-electron-rich benzimidazolium cations, and it results in a quite different retention behavior of star-PCL-Bim from that of star-PCL and commercial HP-35 columns, with “dual-nature” selectivity in separating a mixture including 29 compounds. These favorable chromatographic characteristics demonstrate the great application potential of this material in GC, and provide a prospective strategy to obtain high-performance stationary phases.

Synthesis of chemically-crosslinked multi-arm star-shaped polyurethane with triple-shape memory effect

In this study, chemically-crosslinked multi-arm star-shaped polyurethanes (SPUs) were prepared using three, four, and six-arm polycaprolactone, hexamethylene diisocyanate, and 1, 4-butanediol. The hydrogen bonding indices of soft and hard segments were calculated using Fourier transform infrared spectra. The results indicated that the phase separation among hard and soft segments increased with the increment of PCL arm numbers. Moreover, the results of X-ray diffraction and differential scanning calorimetry showed that the crystallization ability of the three and four-arm SPUs were lower than that for six-arm SPU (6SPU), which is due to their higher crosslinking densities. In addition, the results of the mechanical studies showed that the crosslinking density and degree of crystallinity are the main effective parameters controlling the mechanical properties, by which 6SPU showed higher Young's modulus and lower elongation at break compared to other SPUs. Cyclic shape memory studies showed that 6SPU could fix approximately all the temporary shapes during three cycles and recover 100% of its original shape. Moreover, 6SPU could show triple-shape memory effect (TSME) by which it could fix two different temporary shapes. These results show that 6SPU has a high potential for practical applications due to its good mechanical properties, shape memory fatigue resistance, and TSME.

Effect of the Lignin Structure on the Physicochemical Properties of Lignin-Grafted-Poly(ε-caprolactone) and Its Application for Water/Oil Separation

Lignin-grafted poly(ε-caprolactone) copolymers (lignin-g-PCLs) have shown wide application potentials in coatings, biocomposites, and biomedical fields. However, the structural heterogeneity of lignin affecting the structures and properties of lignin-g-PCL has been scarcely investigated. Herein, kraft lignin is fractionated into four precursors, namely, Fins, F1, F2, and F3, with declining molecular weights and increased hydroxyl contents. Lignin-g-PCLs are synthesized via ring-opening polymerization of ε-caprolactone with lignin and characterized by GPC, FTIR, 1H and 31P NMR, DSC, TGA, and iGC. The mechanical properties, UV barrier, and enzymatic biodegradability of the lignin-g-PCLs are evaluated. Results show that lignin with a higher molecular weight and aliphatic OH favors the copolymerization, leading to lignin-g-PCLs with longer PCL arms. Moreover, lignin incorporation improves the thermal stability, hydrophobicity, and UV-blocking ability but reduces the lipase hydrolyzability of the copolymers. We also demonstrated that the lignin-g-PCL-coated filter paper could successfully separate chloroform–, petroleum ether–, and hexane–water mixtures with an efficiency up to 99.2%. The separation efficiency remains above 90% even after 15 cycles. The structural differences of copolymers derived from the fractionation showed minimal influence on the separation efficiency. This work provides new insights into lignin-based copolymerization and the versatility of lignin valorization.

Effects of hetero‐armed star‐shaped PCL‐PLA polymers with POSS core on thermal, mechanical, and morphological properties of PLA

AbstractIn this study, AB type‐heteroarm star‐shaped poly(ε‐caprolactone)‐poly(lactic acid) (PCL‐PLA) polymers with polyhedral oligomeric silsesquioxane (POSS) core ((PCL)4‐POSS‐(PLA)4, coded as SPLA) were synthesized successfully by using ring opening polymerization and click chemistry techniques together. The synthesized polymers were compounded with commercial PLA at different blending ratios (PLA/SPLA = 100/0, 95/5, 90/10, and 80/20% wt). The effects of heteroarm SPLA polymers having different arm lengths (n = 10, 20, 30, and 50) on morphological, mechanical, and thermal behaviors of PLA were investigated. It is determined that SPLA polymers with four PLA and four PCL arms on its structure enhanced mechanical properties of PLA. The tensile modulus decreased, and lowest modulus values were observed with blends prepared at 80/20 ratio. Elongation at break values increased in all blends, maximum increment was observed with 1,4‐phenylene diisocyanate (PDI) containing SPLA20 blends prepared at 90/10 ratio. This result showed that SPLA20 had optimum chain length for chain extension reactions of between PLA chains. Besides, a trade compatibilizer PDI was utilized to enhance the intercompatibility of binary polymer blends.

Grafting polycaprolactone onto alkaline lignin for improved compatibility and processability

Industrial lignin has a lower compatibility and processability than other polymers during the preparation of composites. To valorize the industrial lignin from spent liquor of alkaline pulping mills, polycaprolactone was grafted onto alkaline lignin to improve its compatibility and processability in this investigation. The lignin-g-polycaprolactone copolymer was prepared by the ring-opening polymerization of the ε-caprolactone monomer under anhydrous conditions and was catalyzed by n-butyl titanate. The techniques of FTIR, 31P NMR and 1H NMR were employed to investigate the reaction mechanisms, including the reaction preference of hydroxyl groups and the average length of the PCL arms. Eventually, the composites of lignin-g-PCL and PCL were prepared by melt blending, and the results demonstrated that the compatibility and processability of lignin was significantly improved by the grafting modification, and that the fracture surface of composite, as well as the mechanical properties, was strongly affected by the average length of the PCL arms grafted on lignin. The best mechanical performance of the composite with tensile strength and bending strength of 1.22 ± 0.05 MPa and 2.23 ± 0.10 MPa, respectively, was achieved by the lignin-g-PCL sample with averaged PCL arm length about 19. This study paves the way for a wider utilization of lignin in composites and biomaterials.

Cyclodextrin based unimolecular micelles with targeting and biocleavable abilities as chemotherapeutic carrier to overcome drug resistance.

An amphiphilic star-shaped copolymer β-CD-g-PCL-SS-PEG-FA, consisting of a β-cyclodextrin (β-CD) core as well as grafted with bioreducible disulfide linkage in PCL-SS-PEG multiarms and targeting folic acid (FA) as end moiety, is designed with unimolecular micelles formation ability for targeted transport of chemotherapeutics to drug resistant tumor cells. Firstly, β-CD was utilized as core to growth PCL arms by ring-opening polymerization (ROP) of ε-CL, before disulfide terminal group transformation to render β-CD-g-PCL-SS-COOH. Secondly, α-hydroxy-ω-amine protected PEG (HO-PEG-NHBoc) was connected to β-CD-g-PCL-SS-COOH to obtain amphiphilic β-CD-g-PCL-SS-PEG, where PCL and PEG were connected via bioreducible disulfide bond. After deprotection of -Boc group, FA was introduced onto the distal end of block arms to obtain the desired β-CD-g-PCL-SS-PEG-FA copolymer. Because of highly branched core-shell amphiphilic structures, β-CD-g-PCL-SS-PEG-FA could act as unimolecular micelles. Interestingly, this unimolecular micelle could release the encapsulated drug in a glutathione (GSH) dependent manner due to disulfide linkage. More importantly, this unimolecular micelle could load doxorubicin (DOX) to promote its cellular uptake in multidrug resistance (MDR) protein overexpression tumor cells, by taking the advantage of FA targeting group and intracellular high GSH level in cancer cells. Together with satisfactory biocompatibility, this novel star-like β-CD-g-PCL-SS-PEG-FA unimolecular micelle could potentially be utilized as targeting nanocarriers in drug resistant cancer therapy.

Designing of energetic miktoarm A2B2 star‐shaped polymer by means of click chemistry and ROP techniques

Novel A2B2‐type energetic miktoarm star‐shaped copolymers composed of two PGN arms and two PCL arms was synthesized by the combination of ring‐opening polymerization (ROP) and “click” chemistry. Initially, diazido end‐functionalized two‐arm PGN, (PGN)2‐(N3)2, was synthesized by ROP of glycidyl nitrate monomers. Subsequently, (PGN)2‐(PCL)2 was obtained from the click reaction between diazido end‐functionalized (PGN)2‐(N3)2 polymers and propargyl‐terminated poly(ε‐caprolactone) (PTPCL). This star copolymer solves problems of PCL (lake of energy) and PGN (low Tg). The Fourier‐transform infrared (FT‐IR), 1H nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC) studies revealed that (PGN)2‐(PCL)2 was successfully obtained. The thermal behavior of star polymer was investigated by thermogravimetric analysis (TGA) and derivative thermogravimetry. The results show that (PGN)2‐(PCL)2 decomposed at two stages. The first stage is seen at 212.6°C which related to degradation of –ONO2 group and second stage attributed to degradation of PCL group which is seen at 346.1°C.

A novel shape memory poly(ɛ-caprolactone)/hydroxyapatite nanoparticle networks for potential biomedical applications

A series of smart shape memory poly(ɛ-caprolactones) (PCL)/hydroxyapatite (HA) networks with different PCL arm lengths are designed and fabricated by the thiol-ene click reaction of thiol-modified HA particles with functional acrylate-terminated PCL. Compared with traditional physical blending of nanoparticles into polymer, this paper constructs a well-defined network architecture on the basis of the molecular level. Thermal and crystalline results indicate that the shape memory transition temperature (Ttrans) of the composites is correlated to the initial PCL diol molecular weight, the melting and crystallization temperature of the networks gradually increase with increasing PCL diol molecular weight. Meanwhile, the HA-PCL networks all exhibit good shape memory capability under thermal stimulus with good shape fixing ratio and recovery ratio irrespective of the molecular weight of PCL diol. An advantage of these network is that the intrinsic biocompatibility of HA nanoparticles as a netpoint for biodegradable PCL renders it a good prospects in the bone biomedical applications.

Synthesis and characterization of an A2B2-type miktoarm star copolymer based on poly(ε-caprolactone) and poly(cyclohexene oxide)

An A2B2-type miktoarm star copolymer with two linear poly(e-caprolactone) (PCL) and two linear poly(cyclohexene oxide) (PCHO) arms was synthesized by using ring-opening polymerization (ROP), click chemistry, and photoinduced cationic polymerization, respectively. The ROP of e-CL with a dihydroxy functional initiator, 3-cyclohexene-1,1-dimethanol, produced a well-defined two-arm PCL with a cyclohexene end-functional group, (PCL)2-CH. The subsequent bromination of (PCL)2-CH followed by azidation gave a diazido end-functionalized PCL, (PCL)2-(N3)2. Then, a well-defined two-arm PCL macrophotoinitiator with benzoin end-functional groups, (PCL)2-(PI)2, was prepared by the azide/alkyne click reaction of this (PCL)2-(N3)2 and PI-alkyne, a separately prepared benzoin photoinitiator bearing a terminal alkyne group. Solid data obtained from the 1H NMR, FT-IR, GPC, UV, and fluorescence spectroscopic studies proved the successful formation of the macrophotoinitiator having a core connected to two PCL chains and two benzoin photofunctional groups (PI). Finally, a novel A2B2-type miktoarm star copolymer was synthesized via photoinduced free radical-promoted cationic polymerization of cyclohexene oxide (CHO) monomer using (PCL)2-(PI)2 as photoinitiator. The obtained star copolymer consists of two PCL arms as A blocks and two PCHO arms as B blocks, (PCL)2-(PCHO)2, and was characterized by 1H NMR, FT-IR, and GPC measurements. The thermal behaviors of all the intermediate and final polymers were studied by thermogravimetric and differential thermal analysis (TG/DTA).

Robust & thermosensitive poly(ethylene glycol)-poly(ε-caprolactone) star block copolymer hydrogels

Novel 8-armed poly(ethylene glycol)-poly(ε-caprolactone) (PEG-PCL) star block copolymers, possessing an amide or an ester group between the PEG core and the PCL arms (PEG20K-(NHCO)-(PCL9)8 and PEG20K-(OCO)-(PCL9)8), are synthesized by ring opening polymerization of ε-caprolactone in toluene at 110 °C initiated by 8-armed star PEG20K-(NH2)8 and PEG20K-(OH)8, respectively. Compared to linear triblock copolymers with a similar hydrophilic/hydrophobic balance and molecular weight, star block copolymers show better aqueous solubility and yield more homogeneous and transparent hydrogels. PEG20K-(NHCO)-(PCL9)8 hydrogels exhibit a significantly higher storage modulus and in vitro stability in comparison with PEG20K-(OCO)-(PCL9)8 hydrogels of similar concentration and molecular weight. 1H NMR analysis of degrading hydrogel samples clearly demonstrates different degradation mechanisms for the ester and amide type star block copolymers. Their robust mechanical properties, the possibility to be formed in situ and their excellent resistance against hydrolytic degradation make these PEG-PCL star block copolymer hydrogels, especially those based on PEG20K-(NHCO)-(PCL9)8, appealing for various biomedical applications.

Complex Thin Film Morphologies of Poly(n-hexyl isocyanate)(5k,10k)–Poly(ε-caprolactone)1–3(10k,17k) Miktoarm Star Polymers

Two series of crystalline–crystalline miktoarm star polymers were prepared and their thin film morphologies were investigated in detail by synchrotron grazing incidence X-ray scattering (GIXS): poly(n-hexyl isocyanate)(5000)–poly(e-caprolactone)1–3(17000) (PHIC(5k)–PCL1–3(17k)) and poly(n-hexyl isocyanate)(10000)–poly(e-caprolactone)1–3(10000) (PHIC(10k)–PCL1–3(10k)). In addition, their thermal properties were examined. All miktoarm star polymers revealed a two-step thermal degradation behavior where the PHIC arm was degraded first, followed by the PCL arm underwent degradation. Interestingly, all miktoarms were found to show a highly enhanced thermal stability, regardless of their molecular weight over 3k to 17k, which might be attributed to their one-end group capped with the counterpart arm(s) via arm-joint formation. Surprisingly, all miktoarm star polymers always developed only lamellar structure in toluene- and chloroform-annealed films via phase-separation, regardless of the length of PHIC arm as w...

Multiarm star poly(ɛ-caprolactone) with hyperbranched polyamidoamine as core capable of selective accommodating cationic or anionic guests

Hyperbranched polyamidoamines (HPAs) were directly employed as macroinitiators to initiate the Sn(Oct)2 catalyzed ring-opening polymerization of ɛ-caprolactone (CL), resulting in multiarm star copolymers with poly(ɛ-caprolactone) (PCL) as shells and HPA as core (HPA-b-PCL). From 1H-NMR characterization it was deduced that both the primary amines and the secondary amide groups of HPAs could initiate the CL polymerization, and the initiation efficiency increased when more CL monomers were fed. The average arm-numbers of the obtained stars were in the range of 115–353. Differential scanning calorimetry measurements demonstrated that the melting and crystallization temperatures, fusion and crystallization enthalpy and the degree of crystallinity of the star polymers increased as the PCL arm length increased. HPA-b-PCL stars could be used as nanocarriers to efficiently accommodate anionic dyes at acidic condition, while load cationic dyes at basic condition. Compared with the dye-loading behavior of multiarm star PCL with the neutral hyperbranched polyglycerol as core, it was deduced that HPA-b-PCL nanocarriers accommodated anionic dyes using the HPA core, while loaded cationic dyes using both the HPA core and the PCL shell. Dynamic light scattering analyses also supported such deduction. Furthermore, HPA-b-PCL nanocarriers could selectively load the anionic Eosin Y or the cationic methylene blue from their mixture at pH = 6 or 9, respectively, realizing their separation.

Study on the crystallization of multiarm stars with a poly(ethyleneimine) core and poly(ϵ-caprolactone) arms of different length

Crystallization of multiarm star systems constituted by a core of poly(ethyleneimine) (PEI) and arms of poly(ϵ-caprolactone) (PCL) was studied by transmission electron microscopy, calorimetry and optical microscopy techniques. Three systems differing on the degree of polymerization of PCL were studied as well as binary mixtures constituted by systems differing on the length of PCL arms. Samples were able to crystallize from both diluted solutions and the melt state giving rise to well-formed lamellae and spherulites, respectively. Lamellae of samples with large PCL arms were highly regular and corresponded to elongated hexagonal crystals with an aspect ratio that decreased with the length of PCL arms.A significant decrease on equilibrium melting temperatures, degree of crystallinity and glass transition temperature was detected for samples having short PCL arms. Crystallization kinetics were also highly influenced by the length of PCL arms, being both nucleation density and secondary nucleation constant increased as the length of PCL arms decreased. Crystallization of star mixtures having different PCL lengths was determined by the larger arms since they initiated the process and subsequently shorter arms were progressively incorporated. A thermal nucleation was characteristic of multiarm star mixtures due to the different crystallization temperature ranges of samples with large and short PCL arms, whereas samples with a homogeneous arm length rendered an athermal nucleation.

Hierarchical Structures in Thin Films of Miktoarm Star Polymers: Poly(n-hexyl isocyanate)(12K)–Poly(ε-caprolactone)1–3(5K)

A series of miktoarm star polymers, [poly(n-hexyl isocyanate)(12K)]–[poly(ε-caprolactone)1–3(5K)] (PHIC–PCL1–3) (composed of a rigid self-assembling PHIC arm and one to three flexible crystallizable PCL arms), were investigated to examine the polymers’ thermal properties and nanoscale thin film morphologies. The miktoarm polymers were stable up to 180 °C. The PHIC and PCL arm components underwent phase separation during the solution casting, drying, and post toluene-annealing processes, forming interesting but very complex thin film morphologies. The resulting thin film morphologies were examined in detail for the first time using synchrotron grazing incidence X-ray scattering (GIXS) measurements and quantitative data analysis. All of the miktoarm star polymer films formed vertically well-oriented lamellar structures, regardless of the number and length of PCL arms. These structures were quite different from the cylindrical structures commonly observed in conventional flexible diblock copolymer films having comparable volume fractions. The individual PHIC and PCL lamellar domains self-assembled to form their own respective morphological structures. The PHIC lamellae consisted of a mixture of horizontal and vertical multibilayer structure domains, as observed in the PHIC homopolymer film. The PCL lamellae formed fringed micelle-like crystals and/or highly imperfect folded crystals that differed significantly from the structures found in a PCL homopolymer film composed of typical folded lamellar crystals. These PCL crystals were formed with a mixture of vertical and horizontal orthorhombic lattices. Overall, the GIXS analysis revealed that the parameters that characterized the hierarchical structures in the thin films depended significantly on the number and length of the PCL arm and its crystallization characteristics as well as the chain rigidity and multibilayer structure formation characteristics of the PHIC arm.

New epoxy thermosets modified with amphiphilic multiarm star polymers as toughness enhancer

The synthesis and characterization of two novel amphiphilic multiarm star polymers with linear polyethylene glycol (PEG) and poly(ε-caprolactone) (PCL) arms and their use as toughening modifiers of epoxy anhydride thermosets are reported. The new star polymers were obtained by partial pegylation of a hyperbranched polyester and subsequent growth of PCL arms. The curing process was studied by calorimetry and thermomechanical analysis, demonstrating the accelerating effect and the influence on gelation of the hydroxyl terminal groups. The curing kinetics was analyzed by model-free and model-fitting methods. The final properties of the resulting materials were determined by thermal and mechanical tests. The addition of the star-like modifiers led only to notable improvement on impact strength in the material containing a 10% of the star with PCL and PEG arms, without compromising glass transition temperature and thermal stability. The morphology of the resulting materials depended on the structure of the toughness modifier used, as demonstrated by electron microscopy, but all modified thermosets obtained showed phase-separated morphologies with nanosized particles.

Divergent synthesis of dendrimer-like pH-responsive macromolecules through a combination of ATRP and ROP for controlled release of anti-cancer drug.

This work is focused on the synthesis and controlled drug release behavior of 8-arm and 12-arm amphiphilic pH-responsive dendrimer-like block copolymers. To study the role of architecture and the number of arms at the critical micelle concentration (CMC) value, differential scanning calorimetry (DSC), micelle size and in vitro controlled release of drug, we investigated a series of 8-arm and 12-arm block copolymers. The poly(acrylic acid) (PAA)-carrying dendrimer-like block copolymers were synthesized in two main steps. First, a second-generation dendrimer-like poly(ε-caprolactone) (PCL) was obtained by ring-opening polymerization (ROP) of ε-caprolactone (CL) from a bis and tris-hydroxylated core. For this goal, a conventional selective AB2-type branching agent for the PCL chain ends was designed: the latter includes a carboxyl (A) group for its attachment to the PCL arm ends and two geminal hydroxyls (B2) for the reiteration of the PCL growth as second generation using ROP. Subsequently, the hydroxyl-end groups quantitatively converted into bromoester groups as atom transfer radical polymerization (ATRP) initiating sites. The second step is the ATRP which thus served to grow poly(tBA) chains. After the hydrolysis of the t-butyl ester groups, amphiphilic, pH-responsive dendrimer-like block copolymers were obtained. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) demonstrated that the micelles exhibit a spherical shape with a size range of 43-64 nm in diameter. As a model drug, quercetin was loaded into the obtained 2G3(PAA)8 and 3G3(PAA)12 micelles via a dialysis method for in vitro release studies and their response to pH variation was investigated. The in vitro cytotoxicity evaluation of the polymers clearly showed that both compounds are safe in a wide range of concentrations (several times above the CMC value).

Synthesis and Characterization of a Novel Star-Shaped Polymers with Biological Compatibility via Ring-Opening Polymerization and Atom Transfer Radical Polymerization

Hydroxyl functional hyperbranched polyester initiators initiated the ring-opening polymerization(ROP) of ε-caprolactone (CL) and the star-shaped polymer with PCL arms using hyperbranched polyester as nuclear was produced. Then, the bromide of star-shaped polymer, initiated the atom transfer radical polymerization (ATRP) of oligo(ethylene oxide) methacrylate (OEOMA) and the star-shaped polymer containing the arms of PCL-b-POEOMA was synthesized ,and the characterization of polymer structure was investigated by NMR.

Studies on the orthogonal assembly of β-cyclodextrin-poly (ε-caprolactone) and ferrocene-poly (ethylene oxide)

A biodegradable multi-arm polymer β-cyclodextrin-poly (ε-caprolactone) (CD-PCL) with a ``jellyfish-like'' structure was obtained, in which flexible and hydrophobic PCL arms were selectively grafted to the wide side of the hydrophilic torus-shaped β-CD. The amphiphilic ``jellyfish-like'' polymer with a hollow cavity and hydrophobic tails could orthogonally self-assemble into a new amphiphilic supramolecular copolymer CD-PCL/FcPEG with poly (ethylene oxide) end-decorated by ferrocene (FcPEG) in aqueous solution based on terminal hydrophobic interactions. The chemical structures of CD-PCL and CD-PCL/FcPEG were characterized by IR, NMR and UV and their self-assembled structures in water were investigated by transmission electron microscopy (TEM) and dynamic light scattering (DLS). CD-PCL alone self-assembled into nano vesicles in water, while CD-PCL/FcPEG into nanospheres. The supramolecular nanospheres were further investigated by cyclic voltammogram. The results indicated that the ferrocenyl groups which were embedded into the hydrophobic core of the supramolecular nanospheres could not transmit electrons or carry out electrochemical oxidation and reduction reaction.

Multi-morphological self-assembled structures in water of a biodegradable β-cyclodextrin-based copolymer

A rigid-coil β-cyclodextrin-poly (ɛ-caprolactone) (CD-PCL) copolymer was synthesized in which biodegradable flexible multi PCL arms were selectively connected onto the wide side of the rigid torus-shaped β-CD through ring-opening polymerization (ROP) of ɛ-caprolactone (CL) and protection/deprotection technique of β-cyclodextrin (β-CD) via trimethylsilyl groups. 1H NMR, FT-IR, and GPC analysis confirmed the “jellyfish-like” branched architecture of CD-PCL copolymers. The self-assembled structures in water of the amphiphilic CD-PCL copolymer were investigated by transmission electron microscopy (TEM), dynamic light scattering (DLC) and viscometry. The results showed that CD-PCL could self-assemble into multi-morphological aggregates such as spheres, rods, vesicles, vesicular clusters and vesicular network in water. Interestingly, hierarchical stripe structure was observed in the formed vesicular network, which was driven by the crystallization of PCL segment in micelles. Moreover, the inclusion ability of copolymer micelles with ferrocenecarboxylic acid was investigated by UV.