Microstructure and properties of novel fluorescent pyrene functionalized PANI/P(VDF‐HFP) blend

We herein report the preparation and properties of the first polymer blend using pyrene functionalized polyaniline (pf‐PANI). The pf‐PANI has been synthesized and its blend has been prepared with the copolymer of vinylidene fluoride and hexafluoropropylene P(VDF‐HFP). The FTIR results reveal intermolecular interaction between the polar amide group of pf‐PANI and the polarized CH₂ group of P(VDF‐HFP). The crystalline phase of PVDF of the copolymer revealed a transformation from α to β crystalline form after blending with pf‐PANI, as found from FTIR and XRD measurements. The calorimetric measurements together with DMA results revealed the blend is partially miscible. The SEM measurements showed that the pf‐PANI has been dispersed uniformly in the P(VDF‐HFP) matrix. The solution photoluminescence spectrum of the pf‐PANI exhibited emission in the purple–blue region and is slightly red shifted for the blend. The possible applications of this flexible fluorescent pf‐PANI/P(VDF‐HFP) has been suggested. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40162.     

Considerations of functional fluoropolymer structure in the design of acrylic–fluorine hybrid PSAs: Graft versus telechelic cooligomers

The objectives of this present article are to design and compare novel acrylic‐fluorine networks as the replacement of fluorinated polyacylate for adhesives application. Firstly, two effective strategies have been developed to achieve functional poly(VDF‐co‐HFP) copolymers based on commercial fluoropolymers. The first approach extensively involved the facile chemical degradation of commercial poly(VDF‐co‐HFP) copolymers to obtain telechelic cooligomers. The second route dealt with the preparation of functional fluoropolymers grafted by multiplex acrylate. Then these two functional and original products were applied as precursors of acrylic‐fluorine hybrid networks in situ polymerization with acrylic monomers. In contrast to original fluoropolymers, functional poly(VDF‐co‐HFP) copolymers exhibited better compatibility with acrylic chain, especially after crosslinking by aluminium acetylacetonate. Additionally, the surface properties of acrylic‐fluorine hybrid networks were discussed based on the SEM and contact angle test. Finally, the peel strength and shear holding power measurements indicated that acrylic‐fluorine hybrid networks can find their potential applications in low surface energy fluorinated PSAs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46038.     

Crystal phase transition dependence of the energy storage performance of poly(vinylidene fluoride) and poly(vinylidene fluoride‐hexafluoropropene) copolymers

Large‐scale mechanical stretching has been performed to modify the crystal phase structures of the pristine poly(vinylidene fluoride) (PVDF) and its copolymer poly(vinylidene fluoride‐hexafluoropropylene) [P(VDF‐HFP)] with various molar contents HFP in an attempt to improve their energy storage performances. It is found that the physical stretched PVDF and P(VDF‐HFP) 95.5/4.5 mol % films have a phase transition from the nopolar α‐phase to highly polar β‐phase, which is different from the P(VDF‐HFP) films with relative high HFP molar contents (α to γ phases). The following results show that the phase transition in these PVDF‐based polymers has a significant effect on their dielectric and energy storage performances. On account of the reformation of the crystalline property and elimination of the impurity defects, an ultra‐high breakdown electric field of ∼900 MV/m has been obtained in all the stretched samples. Consequently, the higher discharged energy densities of 27.1 and 27.7 J/cm³ are calculated from the D–E loops of the β‐PVDF and β‐P(VDF‐HFP) 95.5/4.5 mol % films, respectively. Regarding their excellent discharging energy density of ∼10 J/cm³ under 600 MV/m for thousands of times, the stretched PVDF and its copolymer P(VDF‐HFP)s are promising candidates for high power capacitors applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46306.     

Lewis acid–base property of P(VDF‐co‐HFP) measured by inverse gas chromatography

Poly (vinylidene fluoride‐co‐hexafluoropropylene) P(VDF‐co‐HFP) is an excellent material for polymer electrolytes of lithium ion battery. To enhance the lithium ion transference number, some metal oxides were often embedded into P(VDF‐co‐HFP). The promising mechanism for the increase in lithium ionic conductivity was Lewis acid‐base theory. In this experiment, the Lewis acid–base properties of P(VDF‐co‐HFP) were measured by inverse gas chromatography (IGC). The Lewis acid constant K_a of P(VDF‐co‐HFP) is 0.254, and the base constant K_b is 1.199. Compared with other polymers characterized by IGC, P(VDF‐co‐HFP) is the strongest Lewis basic polymers. Except aluminum ion, lithium ion is the strongest Lewis acidic ion according to their η value of Lewis acids. Therefore, a strong Lewis acid–base interaction will exist between lithium ion and P(VDF‐co‐HFP). This will restrict the transference of lithium ion in P(VDF‐co‐HFP). To enhance the lithium ion transference by blending other metal ions into P(VDF‐co‐HFP), it is suggested that the preferential ions should be Al³⁺, Mg²⁺, Na⁺, and Ca²⁺ because these metal ions have relative large η values. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of microphase‐separated poly(styrene‐co‐sodium styrene sulfonate) membranes using amphiphilic urethane acrylate nonionomers as an reactive compatibilizer

Microphase‐separated poly(styrene‐co‐sodium styrene sulfonate) random copolymer (PSSU) membranes were fabricated through a new copolymerization process. Two immiscible monomers, styrene and sodium styrene sulfonate were dissolved in a single solvent and formed homogeneous solutions, which were directly converted to wall‐to‐wall membranes via radical copolymerization process with microphase separation. Since urethane acrylate nonionomer (UAN) chain has amphiphilicity as well as reactivity with vinyl monomers, UAN chain could act not only as compatibilizer for polystyrene and poly(sodium styrene sulfonate), but also as macrocrosslinker, which makes it possible for the formation of crosslinked copolymer of two immiscible polymers without macrophase separation. TEM image of the PSSU membranes showed that nanosized hydrophilic domains formed by hydrophilic/hydrophobic microphase separation were dispersed at hydrophobic matrix phase. PSSU membranes fabricated using UAN chain having longer chain length of polyethylene oxide showed bigger size of hydrophilic domains, which was also confirmed by TEM images. Fabricated PSSU membranes showed proton conductivity higher than 10^?2 S/cm and methanol permeability lower than 10^?7 cm²/s of Nafion® 117 membranes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Study on the effect of acid‐ or iodine‐doping on the properties of copolymer C1–4poly‐phenylene‐vinylene‐ether

In this article, the new red‐colored copolymer, referred to as C_1–4poly‐phenylene‐vinylene‐ ether (C_1–4PPV‐ether) is built as a PPV polymer with some conjugated links (? CH?CH? ) that are changed into ethylic‐ether links (? CH₂? O? CH₂? ) and whose modified phenyl ring is grafted, respectively, in two and five positions with methoxy and butoxy groups. The C_{1– 4}PPV‐ether is doped with protonic acid or iodine. The infrared absorption (IR), optical density, X‐ray photoelectron spectroscopy (XPS), and electron spin resonance (ESR) show that there is a charge transfer complex formed between the copolymer and the doping species (iodine or acidic dopants). From IR, XPS, and ESR analysis, we deduced that the doping mechanism of the copolymer is, respectively, a protonation of the double links in PPV in the case of the protonic acid doping process and a grafting of the iodine to the ether links in the case of iodine‐doping process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1858–1866, 2002     

Preparation and performance study on P(St‐MMA)‐SiO2 doped P(VDF‐HFP) based composite polymer electrolyte

The organic–inorganic hybrid material poly(styrene‐methyl methacrylate)‐silica (P(St‐MMA )‐SiO₂) was successfully prepared by in situ polymerization confirmed by Fourier transform infrared spectroscopy and was employed to fabricate poly(vinylidene fluoride‐hexafluoropropylene) (P(VDF‐HFP )) based composite polymer electrolyte (CPE ) membrane. Desirable CPEs can be obtained by immersing the CPE membranes into 1.0 mol L^?1 LiPF₆‐EC /DMC /EMC (LiPF₆ ethylene carbonate + dimethyl carbonate + ethylmethyl carbonate) liquid electrolyte for about 0.5 h for activation. The corresponding physicochemical properties were characterized by SEM , XRD , electrochemical impedance spectroscopy and charge–discharge cycle testing measurements. The results indicate that the as‐prepared CPEs have excellent properties when the mass ratio of the hybrid P(St‐MMA )‐SiO ₂ particles to polymer matrix P(VDF‐HFP ) reaches 1:10, at which point the SEM analyses show that the as‐prepared P(St‐MMA )‐SiO ₂ particles are uniformly dispersed in the membrane and the CPE membrane presents a homogeneous surface with abundant interconnected micropores. The XRD results show that there may exist interaction forces between the P(St‐MMA )‐SiO ₂ particles and the polymer matrix, which can obviously decrease the crystallinity of the composite membrane. Moreover, the ionic conductivity at room temperature and the electrochemical working window of the CPE membrane can reach 3.146 mS cm^?1 and 4.7 V, respectively. The assembled LiCoO₂/CPE /Li coin cell with the CPE presents excellent charge–discharge and C ‐rate performance, which indicates that P(St‐MMA )‐SiO ₂ hybrid material is a promising additive for the P(VDF‐HFP ) based CPE of the lithium ion battery. © 2016 Society of Chemical Industry     

Preparation and dispersibility of poly(L‐lactide)‐grafted silica nanoparticle

To improve dispersibility of silica nanoparticle in organic solvents, the grafting of poly(L ‐lactide) (PLLA) onto silica nanoparticle surface by ring‐opening polymerization of L‐lactide (LA) was investigated in the presence of an amidine base catalyst. The ring‐opening polymerization of LA successfully initiated in the presence of silica having amino groups (silica‐NH₂) and an amidine base catalyst to give PLLA‐grafted silica, but not in the presence of untreated silica (silica‐OH). In the absence of the amidine base catalyst no ring‐opening polymerization of LA even in the presence of silica‐NH₂ and no grafting of PLLA onto silica were observed. It became apparent that the amidine base catalyst acts as an effective catalyst for the ring‐opening graft polymerization of LA from the surface of silica‐NH₂. In addition, it was found that the percentage of PLLA grafting onto silica could be controlled according to the reaction conditions. The average particle size of PLLA‐grafted silica was smaller than that of silica‐NH₂. Therefore, it was considered that the aggregation structure of silica nanoparticles was considerably destroyed by grafting of PLLA onto the surface. The PLLA‐grafted silica gave a stable dispersion in polar solvents, which are good solvents for PLLA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

High temperature surface neutralization process with random copolymers for block copolymer self‐assembly

Hydroxyl terminated poly(styrene‐r ‐methyl methacrylate) (P(S‐r ‐MMA )) random copolymers (RCPs ), with molecular weight (M _n) spanning from 1700 to 69 000 g mol^?1 and equal styrene unit content, were grafted at different temperatures onto a silicon oxide surface and subsequently used to study the orientation of nanodomains with respect to the substrate, in cylinder forming polystyrene‐b ‐poly(methyl methacrylate) (PS ‐b ‐PMMA ) block copolymer thin films. When the grafting temperature increases from 250 to 310 °C, a substantial increase in the grafting rate is observed. In addition, an increase in the surface neutralization efficiency occurs thus resulting in an increase in the robustness of the surface neutralization step. These data revealed that the neutralization of the substrate is the result of a complex interplay between RCP film characteristics and underlying substrate properties that can be finely tuned by properly adjusting the temperature of the grafting process. © 2016 Society of Chemical Industry     

Microwave promoted synthesis of chitosan‐graft‐poly(acrylonitrile)

Using microwave (MW) irradiation, polyacrylonitrile was grafted onto chitosan with 170% grafting yield under homogeneous conditions in 1.5 min in the absence of any radical initiator or catalyst. Under similar conditions a maximum grafting of 105% could be achieved when the K₂S₂O₈/ascorbic acid redox system was used as radical initiator in a thermostatic water bath at 35 ± 2°C. The representative graft copolymer was characterized by Fourier transform infrared spectra, thermogravimetric analysis, and X‐ray diffraction measurement, taking chitosan as a reference. The effects of such reaction variables as monomer/chitosan concentration, MW power, and exposure time on the graft co polymerization were studied. A probable mechanism for grafting without the redox system under microwaves was proposed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 820–825, 2005     

Preparation of monodispersed ZrO2 nanoparticles and their applications in poly[(vinylidene fluoride)‐co‐hexafluoropropylene]‐based composite polymer electrolytes

To improve the electrochemical performance of pure poly[(vinylidene fluoride)‐co‐hexafluoropropylene] (P(VDF‐HFP))‐based gel polymer electrolytes, different amounts of monodispersed ZrO₂ nanoparticles were introduced to fabricate P(VDF‐HFP)/ZrO₂ composite polymer electrolytes (CPEs) using the phase inversion method and activated processes, in which the monodispersed ZrO₂ nanoparticles were synthesized by an easy route without any chelating agents or surfactants, and confirmed using scanning electron microscopy, particle size distribution measurement and X‐ray diffraction. The characterization results show that the as‐fabricated CPE membranes present not only an abundant porous structure, but also an improved mechanical strength. In particular, sample CPE‐5 presents the best properties when the doped content of the monodispersed ZrO₂ nanoparticles reaches 5 wt% in the polymer matrix, in which the liquid uptake and ionic conductivity at room temperature are about 192.4% and 3.926 mS cm^?1, and the electrochemical working window and thermal decomposition temperature can increase to 5.1 V and 420 °C, respectively. Moreover, an assembled LiCoO₂/CPE‐5/Li coin cell can deliver excellent rate and cycling performance, in which the discharge specific capacity of the cell can show about 83.95% capacity retention at 2.0 C after 85 cycles. © 2018 Society of Chemical Industry     

Radiation‐induced grafting of acrylic acid and sodium styrene sulfonate onto high‐density polyethylene membranes. II. Thermal and chemical properties

Strong acid cation‐exchange membranes were obtained by radiation‐induced grafting of acrylic acid and sodium styrene sulfonate onto high‐density polyethylene (HDPE). Thermal and chemical properties of the cation‐exchange membranes were investigated. The effectiveness of ? SO₃Na containing membranes was conformed in inducing high resistance to oxidative degradation. The char residue of the grafted HDPE is greater than that of ungrafted HDPE. It shows that the branch chains, including ? SO₃Na and ? COOH groups, give catalytic impetus to the charring. The crystallinity of the grafted membranes was decreased when increasing the grafting yield. It was assumed that the decreased crystallinity was due to collective effects of the inherent crystallinity dilution by the amorphous grafted chains and the crystal distortion of the HDPE component. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99:3396–3400, 2006     

Comparative investigations of radiation‐grafted proton‐exchange membranes prepared using single‐step and conventional two‐step radiation‐induced grafting methods

Proton‐exchange membranes containing poly(styrene sulfonic acid) grafts hosted in poly(vinylidene fluoride) (PVDF) films were prepared using two radiation‐induced grafting methods: a single‐step grafting method (SSGM) involving grafting of sodium styrene sulfonate onto electron beam (EB)‐irradiated PVDF films and a conventional two‐step grafting method (CTSGM) in which styrene monomer is grafted onto EB‐irradiated PVDF films and subsequently sulfonated. Differential scanning calorimetry, universal mechanical testing and scanning transmission electron microscopy were used to evaluate the thermal, mechanical and structural changes developed in the membranes during the preparation procedures. Physicochemical properties such as water uptake, hydration number and ionic conductivity were studied as functions of ion‐exchange capacity and the results obtained were correlated with the structural changes accompanying each preparation method. Membranes obtained using the SSGM were found to have superior properties compared to their counterparts prepared using the CTSGM suggesting the former method is more effective than the latter for imparting desired functionality and stability properties to the membranes. Copyright © 2010 Society of Chemical Industry     

Drug‐release behavior of chitosan‐g‐poly(vinyl alcohol) copolymer matrix

Chitosan‐g‐poly(vinyl alcohol) (PVA) copolymers with different grafting percent were prepared by grafting water‐soluble PVA onto chitosan. The drug‐release behavior was studied using the chitosan‐g‐PVA copolymer matrix containing prednisolone in a drug‐delivery system under various conditions. The relationship between the amount of the released drug and the square root of time was linear. From this result, the drug‐release behavior through the chitosan‐g‐PVA copolymer matrix is shown to be consistent with Higuchi's diffusion model. The drug‐release apparent constant (K_H) was slightly decreased at pH 1.2, but increased at pH 7.4 and 10 according to the increasing PVA grafting percent. Also, K_H was decreased by heat treatment and crosslinking. The drug release behavior of the chitosan‐g‐PVA copolymer matrix was able to be controlled by the PVA grafting percent, heat treatment, or crosslinking and was also less affected by the pH values than was the chitosan matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 458–464, 1999     

Relationship Between Methanol Permeability and Structure of Different Radiation‐Grafted Membranes

Styrene grafted and sulfonated poly(vinylidene fluoride) and poly(vinylidene fluoride‐co‐hexafluoropropylene) films are candidates as electrolytes in direct methanol fuel cells. Their behaviour in water, 1 and 3 mol dm^–3 aqueous methanol, and pure methanol were studied. According to SAXS results, water and methanol‐water solutions have similar effects on the membranes, i.e., the lamellar period increases and the ionic domains enlarge. Furthermore, differences in the ionic domain structures in pure methanol and water were observed. These structural changes together with dissimilar liquid uptakes in water and in methanol are reflected as changes in the conductivities. An increase in the SAXS intensity and changes in the Bragg distance of the ionic peak were observed in methanol compared to aqueous solutions. This may be related to the hydrophobicity of the CH₃ group on methanol. Dissimilarities in methanol permeability through the radiation‐grafted membrane can be related to structural differences in membranes observed with SAXS. Permeabilities were observed to be lower for the radiation‐grafted membranes compared to Nafion® 115, which compensates for the higher area resistance of the experimental membranes and thus improves their performance in a fuel cell.     

Preparation and properties of alkaline anion exchange membrane with semi‐interpenetrating polymer networks based on poly(vinylidene fluoride‐co‐hexafluoropropylene)

Alkaline anion exchange membrane with semi‐interpenetrating polymer network (s‐IPN) was constituted based upon quaternized poly(butyl acrylate‐co‐vinylbenzyl chloride) (QPBV) and poly(vinylidene fluoride‐co‐hexafluoropropylene) [P(VDF‐HFP)]. The QPBV was synthesized via the free radical copolymerization, followed by quaternization with N‐methylimidazole. The s‐IPN system was constituted by melting blend of QPBV and P(VDF‐HFP), and then crosslinking of P(VDF‐HFP). Ion exchange capacity, water uptake, mechanical performance, and thermal stability of these membranes were characterized. TEM showed that alkaline anion exchange membrane exhibited s‐IPN morphology with microphase separation. The fabricated s‐IPN membrane exhibited hydroxide ion conductivity up to 15 mS cm^?1 at 25 °C and a maximum DMFC power density of 46.55 mW cm^?2 at a load current density of 98 mA cm^?2 at 30 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45775.     

The Ionic Conductivity of a Nafion® 1100 Series of Proton‐exchange Membranes Re‐cast from Butan‐1‐ol and Propan‐2‐ol

The ionic conductivity of Nafion® 1100 extruded membranes re‐cast from solutions of butan‐1‐ol and propan‐2‐ol is measured in 0.5 mol dm^–3 H₂SO₄ at 295 K, using an immersed, four‐electrode d.c. technique. The general trend is an increasing conductivity for the thicker membranes. Materials which were solution‐cast from butan‐1‐ol yielded the highest conductivity while a series of membranes with lower conductivities (similar to those of an extruded Nafion® 1100 series of membranes) was found using propan‐2‐ol. The conductivity results indicate that membranes manufactured by extrusion and casting from various solvents might have different structures. Differences in the water content and conductivity of the membranes are considered to arise from the impact of processing conditions on the surface and bulk structure of the membranes.     

Studies on mechanical and morphological behavior of hybrid nanoclay‐reinforced EPDM‐g‐TMEVS/PS blends

A new copolymer of tris(2‐methoxyethoxy) vinylsilane (TMEVS)‐grafted ethylene–propylene–diene elastomer (EPDM‐g‐TMEVS) has been developed by grafting of TMEVS onto EPDM by using dicumylperoxide (DCP) initiator. The linear polystyrene blends (EPDM‐g‐TMEVS/PS) based on EPDM‐g‐TMEVS have been synthesized with varying weight percentages of polystyrene in a twin‐screw extruder. In a similar manner, the dynamically vulcanized and nanoclay‐reinforced polystyrene blends have also been developed using DCP and organically modified montmorillonite clay separately by means of a twin‐screw extruder. The grafting of TMEVS onto EPDM at allylic position present in the third monomer of EPDM has been confirmed by Fourier Transform infrared spectroscopy. The effect of silane‐grafted EPDM and concentration of nanoclay on mechanical properties of polystyrene blends has been studied as per ASTM standards. The morphological behavior of these blends has been investigated using scanning electron microscope. It was observed that the incorporation of silane‐grafted EPDM enhanced the impact strength and the percentage elongation of linear‐ and dynamically vulcanized blends. However, the values of tensile strength, flexural strength, flexural modulus, and hardness of the blends were found to be decreasing with the increase of silane‐grafted EPDM. In the case of nanoclay‐reinforced polystyrene blends, the values of impact strength, tensile strength, flexural strength, flexural modulus, and hardness were increased with an increase in the concentration of nanoclay. XRD studies have been carried out to confirm the formation of nanoclay‐reinforced EPDM‐g‐TMEVS/PS blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Surface microphase separation in PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films

Well‐defined poly(dimethylsiloxane)‐block‐poly(methyl methacrylate)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) (PDMS‐b‐PMMA‐b‐PHFBMA) triblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films was investigated. The microstructure of the block copolymers was investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Surface composition was studied by X‐ray photoelectron spectroscopy (XPS). The chemical composition at the surface was determined by the surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films. The increase of the PHFBMA content could strengthen the microphase separation behavior in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films and reduce their surface tension. Comparison between the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymers and the PDMS‐b‐PHFBMA diblock copolymers showed that the introduction of the PMMA segments promote the fluorine segregation onto the surface and decrease the fluorine content in the copolymers with low surface energy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermoresponsive poly(ϵ‐caprolactone)‐graft‐poly(N‐isopropylacrylamide) graft copolymers prepared by a combination of ring‐opening polymerization and sequential azide–alkyne click chemistry

A straightforward strategy is described to synthesize poly(?‐caprolactone)‐graft‐poly(N‐isopropylacrylamide) (PCL‐g‐PNIPAAm) amphiphilic graft copolymers consisting of potentially biodegradable polyester backbones and thermoresponsive grafting chains. PCL with pendent chlorides was prepared by ring‐opening polymerization, followed by conversion of the pendent chlorides to azides. Alkyne‐terminated PNIPAAm was synthesized by atom transfer radial polymerization. Then, the alkyne end‐functionalized PNIPAAm was grafted onto the PCL backbone by a copper‐catalyzed azide–alkyne cycloaddition. PCL‐g‐PNIPAAm graft copolymers self‐assembled into spherical micelles comprised of PCL cores and PNIPAAm coronas. The critical micelle concentrations of the graft copolymers were in the range 7.8–18.2 mg L^?1, depending on copolymer composition. Mean hydrodynamic diameters of micelles were in the range 65–135 nm, which increased as the length of grafting chains grew. PCL‐g‐PNIPAAm micelles were thermosensitive and aggregated upon heating. © 2014 Society of Chemical Industry