Ionic organic/inorganic materials. I. Novel cationic siloxane copolymers containing quaternary ammonium salt groups in the backbone

The synthesis and characterization of some novel cationic siloxanes copolymers containing quaternary ammonium salt (QAS) groups in the backbone is reported in this article. One cationic oligomer having QAS in the backbone and reactive groups like 2,3‐epoxypropyl and 2‐hydroxy‐3‐chloropropyl (RCO) as well as 1,3‐bis(3‐aminopropyl)tetramethyldisiloxane or α,ω‐bis(3‐aminopropyl)oligodimethylsiloxane (AP) were used as precursors for this goal. Elemental analysis, IR and ¹H NMR spectroscopy, thermogravimetric analysis, and X‐ray photoelectron spectroscopy were used to characterize the obtained copolymers. The thermal stability of the cationic siloxane copolymer increased when the siloxane oligomer having a high number of siloxane units in the chain (AP) was used as a precursor. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3570–3578, 2002     

Synthesis of four‐armed poly(ε‐caprolactone)‐block‐poly(ethylene oxide) by diethylzinc catalyst

Biodegradable, amphiphilic, four‐armed poly(?‐caprolactone)‐block‐poly(ethylene oxide) (PCL‐b‐PEO) copolymers were synthesized by ring‐opening polymerization of ethylene oxide in the presence of four‐armed poly(?‐caprolactone) (PCL) with terminal OH groups with diethylzinc (ZnEt₂) as a catalyst. The chemical structure of PCL‐b‐PEO copolymer was confirmed by ¹H NMR and ¹³C NMR. The hydroxyl end groups of the four‐armed PCL were successfully substituted by PEO blocks in the copolymer. The monomodal profile of molecular weight distribution by gel permeation chromatography provided further evidence for the four‐armed architecture of the copolymer. Physicochemical properties of the four‐armed block copolymers differed from their starting four‐armed PCL precursor. The melting points were between those of PCL precursor and linear poly(ethylene glycol). The length of the outer PEO blocks exhibited an obvious effect on the crystallizability of the block copolymer. The degree of swelling of the four‐armed block copolymer increased with PEO length and PEO content. The micelle formation of the four‐armed block copolymer was examined by a fluorescent probe technique, and the existence of the critical micelle concentration (cmc) confirmed the amphiphilic nature of the resulting copolymer. The cmc value increased with increasing PEO length. The absolute cmc values were higher than those for linear amphiphilic block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 950–959, 2004     

Direct synthesis of amphiphilic block copolymers from glycidyl methacrylate and poly(ethylene glycol) by cationic ring‐opening polymerization and supramolecular self‐assembly thereof

Amphiphilic block copolymers composed of a hydrophilic poly(ethylene glycol) (PEG) block and a hydrophobic poly(glycidyl methacrylate) (PGMA) block were synthesized through cationic ring‐opening polymerization with PEG as the precursor. The model reactions indicated that the reactivity of the epoxy groups was higher than that of the double bonds in the bifunctional monomer glycidyl methacrylate (GMA) under the cationic polymerization conditions. Through the control of the reaction time in the synthesis of block copolymer PEG‐b‐PGMA, a linear GMA block was obtained through the ring‐opening polymerization of epoxy groups, whereas the double bond in GMA remained unreacted. The results showed that the molecular weight of the PEG precursor had little influence on the grafting of GMA, and the PGMA blocks almost kept the same length, despite the difference of the PEG blocks. In addition, the PGMA blocks only consisted of several GMA units. The obtained amphiphilic PEG‐b‐PGMA block copolymers could form polymeric core–shell micelles by direct molecular self‐assembly in water. The crosslinking of the PGMA core of the PEG‐b‐PGMA micelles, induced by ultraviolet radiation and heat instead of crosslinking agents, greatly increased the stability of the micelles. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2038–2047, 2005     

Modified poly(ϵ-caprolactone)s and their use for drug-encapsulating nanoparticles

Poly(ϵ-caprolactone) (PCL)-polydimethylsiloxane diblock and triblock copolymers and poly(ϵ-caprolactone-co-4-ethylcaprolactone) random copolymers were prepared through the homogeneously catalyzed coordination anionic polymerization of ϵ-caprolactone (CL) and the copolymerization of CL with 4-ethyl-ϵ-caprolactone (EtCL) in the presence of hydroxy-terminated polysiloxanes or allyl alcohol as chain-transfer agents, respectively. Polysiloxane precursors with hydroxypropyl or hydroxyethyl propyl ether end groups were obtained by the hydrosilation of the appropriate unsaturated alcohol with monofunctional or difunctional hydro-terminated polysiloxanes of different molecular weights. As proven by differential scanning calorimetry analysis, the presence of siloxane blocks and EtCL units determined the diminished copolymer crystallinity, which was shown by the reduced melting temperatures and enthalpy of fusion with respect to those of pure PCL. Both types of copolymers were found to form, in the presence of a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) emulsifier, monodisperse and stable nanoparticles able to encapsulate different types of bioactive compounds (Vitamin E and indomethacin). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 689–700, 2004     

Ionic organic/inorganic materials. III. Stimuli responsive hybrid hydrogels based on oligo(N,N‐dimethylaminoethylmethacrylate) and chloroalkyl‐functionalized siloxanes

Ionic organic/siloxane networks containing quaternary ammonium salt (QAS) sequences in the cross‐linking bridges were obtained by the Menshutkin reaction of oligo(N,N‐dimethylaminoethylmethacrylate) (ODMAEM) with a telechelic chloroalkylated siloxane (CAS), such as 1,3‐bis‐(chloromethyl)‐1,1,3,3‐tetramethyldisiloxane, 1,3‐bis‐(chloropropyl)‐1,1,3,3‐tetramethyldisiloxane, and α,ω‐bis(chloromethyl) oligodimethylsiloxane. The resulted structures were investigated by Fourier transform infrared spectroscopy emphasizing the presence of both organic and siloxane moieties. The thermogravimetric analysis under inert atmosphere of the networks, besides the thermal stability, gave also information on the composition of hybrid hydrogels. The morphology of the lyophilized networks was evidenced by environmental scanning electron microscopy, as a function of CAS structure and CAS: ODMAEM feed molar ratio. The swelling response of the ionic networks in water as a function of pH and counterion nature and concentration as well as the water vapors sorption capacity in dynamic regime were evaluated. The properties of the ionic hybrid hydrogels were correlated with the reactants feed molar ratio and concentration of the reaction mixture, CAS type, and the presence of a catalyst. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009     

Biologically active polymers. V. Synthesis and antimicrobial activity of modified poly(glycidyl methacrylate‐co‐2‐hydroxyethyl methacrylate) derivatives with quaternary ammonium and phosphonium salts

Antimicrobial copolymers bearing quaternary ammonium and phosphonium salts based on a copolymer of glycidyl methacrylate and 2‐hydroxyethyl methacrylate were synthesized. Poly(glycidyl methacrylate‐co‐2‐hydroxyethyl methacrylate) was modified for the introduction of chloromethyl groups by its reaction with chloroacetyl chloride. The chloroacetylated copolymer was modified for the production of quaternary ammonium or phosphonium salts. The antimicrobial activity of the obtained copolymers was studied against gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella sp., and Salmonella typhae), gram‐positive bacteria (Bacillus subtilus and B. cereus), and the fungus Trichophyton rubrum by the cut‐plug method. The results showed that the three copolymers had high antimicrobial activity. A control experiment was carried out on the main polymer without ammonium or phosphonium groups. The copolymer bearing quaternary salt made from tributyl phosphine was the most effective copolymer against both gram‐negative and gram‐positive bacteria and the fungus T. rubrum. The diameters of the inhibition zones ranged between 20 and 60 mm after 24 h. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2384–2393, 2002     

Biodegradable/biocompatible ABC triblock copolymer bearing hydroxyl groups in the middle block

New biodegradable/biocompatible ABC block copolymers, poly(ethylene oxide)‐b‐poly(glycidol)‐b‐poly(L ,L ‐lactide) (PEO‐PGly‐PLLA), were synthesized. First, PEO‐b‐poly(1‐ethoxyethylglycidol)‐b‐PLLA was synthesized by a successive anionic ring‐opening copolymerization of ethylene oxide, 1‐ethoxyethylglycidyl ether, and L ,L ‐lactide initiated with potassium 2‐methoxyethanolate. In the second step, the 1‐ethoxyethyl blocking groups of 1‐ethoxyethylglycidyl ether were removed at weakly acidic conditions leaving other blocks intact. The resulting copolymers were composed of hydrophilic and hydrophobic segments joined by short polyglycidol blocks with one hydroxyl group in each monomeric unit. These hydroxyl groups may be used for further copolymer transformations. The PEO‐PGly‐PLLA copolymers with a molecular weight of PLLA blocks below 5000 were water‐soluble. Above the critical micellar concentration (ranging from 0.05 to1.0 g/L, depending on the composition of copolymer), copolymers formed macromolecular micelles with a hydrophobic PLLA core and hydrophilic PEO shell. The diameters of the micelles were about 25 nm. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3750–3760, 2003     

Microphase separation in block‐random copolymers of styrene, 4‐acetoxystyrene,and 4‐hydroxystyrene

“Block‐random” copolymers—where one or more blocks are themselves random copolymers—offer a flexible modification to the usual block copolymer architecture. For example, in a poly(A)‐poly(A‐ran‐B) diblock consisting of monomer units A and B, the interblock segregation strength can be continuously tuned through the B content of the random block, allowing the design of block copolymers with accessible order‐disorder transitions at arbitrarily high molecular weights. Moreover, the development of controlled radical polymerizations has greatly expanded the palette of accessible monomer units A and B, including units with strongly interacting functional groups. We synthesize a range of copolymers consisting of styrene (S) and acetoxystyrene (AS) units, including copolymers where one block is P(S‐ran‐AS), through nitroxide‐mediated radical polymerization. At sufficiently high molecular weights, near‐symmetric PS‐PAS diblocks show well‐ordered lamellar morphologies, while dilution of the repulsive S‐AS interactions in PS‐P(S‐ran‐AS) diblocks yields a phase‐mixed morphology. Cleavage of a sufficient fraction of the AS units in a phase‐mixed PS‐P(S‐ran‐AS) diblock to hydrogen‐bonding hydroxystyrene (HS) units yields, in turn, a microphase‐separated melt. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47:2106–2113, 2009.     

Thermosensitive polyalcohols: Synthesis via living cationic polymerization of vinyl ethers with a silyloxy group

Thermosensitive homopolymers and copolymers with hydroxy groups were synthesized via the living cationic polymerization of Si‐containing vinyl ethers. The cationic homopolymerization and copolymerization of five vinyl ethers with silyloxy groups, each with a different spacer length, were examined with a cationogen/Et_1.5AlCl_1.5 initiating system in the presence of an added base. When an appropriate base was added, the living cationic polymerization of Si‐containing monomers became feasible, giving polymers with narrow molecular weight distributions and various block copolymers. Subsequent desilylation gave well‐defined polyalcohols, in both water‐soluble and water‐insoluble forms. One of these polyalcohols, poly(4‐hydroxybutyl vinyl ether), underwent lower‐critical‐solution‐temperature‐type thermally induced phase separation in water at a critical temperature (T_PS) of 42 °C. This phase separation was quite sensitive and reversible on heating and cooling. The phase separation also occurred sensitively with random copolymers of thermosensitive and hydrophilic or hydrophobic units, the T_PS values of which in water could be controlled by the monomer feed ratio. The thermal responsiveness of this polyalcohol unit made it possible to prepare novel thermosensitive block and random copolymers consisting solely of alcohol units. One example prepared in this study was a 20 wt % aqueous solution of a diblock copolymer consisting of thermosensitive poly(4‐hydroxybutyl vinyl ether) and water‐soluble poly(2‐hydroxyethyl vinyl ether) segments, which transformed into a physical gel above 42 °C. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3300–3312, 2003     

Synthesis of bipolar charge transporting block copolymers and characterization for organic light‐emitting diode

A series of hole and electron transporting random and block copolymers consisting of triphenylamine moiety as a hole transporting unit and oxadiazole moiety as an electron transporting unit have been prepared via a nitroxide mediated radical polymerization. Oxadiazole monomers with t‐butyl or trifluoromethyl groups, 2 and 7, respectively, were used for copolymerization. Photoluminescent measurements of polymers revealed that the formation of the exciplex between triphenylamine and oxadiazole units tends to occur in the order of random copolymers, block copolymers, and polymer blends, implying phase‐separated morphologies in block or blend systems. The polymers were applied for OLED devices, and we found that the morphology in the polymer layer critically affected device performance. The block copolymer comprising hole and electron transporting units with the composition of 14/86 showed the highest external quantum efficiency over 10%. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1461–1468, 2010     

Segmented polyurethanes derived from novel siloxane–carbonate soft segments for biomedical applications

A novel macrodiol based on mixed silicone and carbonate chemistries was synthesized and used as a soft segment precursor in the synthesis of two series of segmented polyurethane (PU) copolymers varying in hard segment content and soft segment molecular weight. The hard segments in these copolymers were derived from 4,4‐methylene diphenyl diisocyanate and 1,4‐butane diol. The phase transitions, microphase separation behavior, and mechanical properties of the copolymers were investigated using a variety of experimental methods. When compared with segmented PU copolymers having predominately poly(dimethyl siloxane) soft segments, these siloxane–carbonate soft segment copolymers exhibit enhanced intersegment mixing, and consequently relatively low mechanical modulus. With relatively low modulus and siloxane units in the soft phase, the siloxane–carbonate PUs have potential for use in cardiac and orthopedic biomedical applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Synthesis and morphology of polyethylene‐block‐poly(methyl methacrylate) through the combination of metallocene catalysis with living radical polymerization

Polyethylene‐block‐poly(methyl methacrylate) (PE‐b‐PMMA) was successfully synthesized through the combination of metallocene catalysis with living radical polymerization. Terminally hydroxylated polyethylene, prepared by ethylene/allyl alcohol copolymerization with a specific zirconium metallocene/methylaluminoxane/triethylaluminum catalyst system, was treated with 2‐bromoisobutyryl bromide to produce terminally esterified polyethylene (PE‐Br). With the resulting PE‐Br as an initiator for transition‐metal‐mediated living radical polymerization, methyl methacrylate polymerization was subsequently performed with CuBr or RuCl₂(PPh₃)₃ as a catalyst. Then, PE‐b‐PMMA block copolymers of different poly(methyl methacrylate) (PMMA) contents were prepared. Transmission electron microscopy of the obtained block copolymers revealed unique morphological features that depended on the content of the PMMA segment. The block copolymer possessing 75 wt % PMMA contained 50–100‐nm spherical polyethylene lamellae uniformly dispersed in the PMMA matrix. Moreover, the PE‐b‐PMMA block copolymers effectively compatibilized homopolyethylene and homo‐PMMA at a nanometer level. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3965–3973, 2003     

Control through monomer placement of surface properties and morphology of fluoromethacrylate copolymers

The arrangement of monomers and morphology of fluorinated copolymers of methyl methacrylate (MMA) were found to be important for controlling the surface energy of the materials when formed into thin films. Novel copolymers of MMA and 2,2,3,3,4,4,4‐heptafluorobutyl methacrylate (F3MA) were prepared with different monomer placement, namely statistical and block arrangements of the monomer units. The surface energies decreased with increasing incorporation of F3MA, in a manner consistent with previous reports for similar copolymers; however, the surface energies of the block copolymers were consistently lower than the statistical copolymers. This was interpreted as arising from conformational restriction of presentation of the fluoromonomers to the surface in the statistical copolymers, and formation of phase‐separated domains at the surface of the block copolymers. The morphology of the block copolymers was confirmed by small angle X‐ray scattering measurements, which allowed calculation of a solubility parameter for the fluorinated segments. The results have implications for the design of more environmentally acceptable materials with ultra‐low surface energies. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2633–2641     

Microphase‐separated structure of 1,3‐cyclohexadiene/butadiene triblock copolymers and its effect on mechanical and thermal properties

We report the effect of microphase‐separated structure on the mechanical and thermal properties of several poly(1,3‐cyclohexadiene‐block‐butadiene‐block‐1,3‐cyclohexadiene) triblock copolymers (PCHD‐block‐PBd‐block‐PCHD) and of their hydrogenated derivatives: poly(cyclohexene‐block‐ethylene/butylene‐block‐cyclohexene) triblock copolymers (PCHE‐block‐PEB‐block‐PCHE). Both mechanical strength and heat‐resistant temperature (ex. Vicat Softening Temperature: VSPT) tended to increase with an increase in the 1,3‐cyclohexadiene (CHD)/butadiene ratio. On the other hand, heat resistance of the hydrogenated block copolymer was found to be higher than that of the unhydrogenated block copolymer. However, the mechanical strength was lower than those of the unhydrogenated block copolymer with the same ratio of CHD to butadiene. To clarify the relationship between the higher order structures of those block copolymers and their properties, we observed the microphase‐separated structure by transmission electron microscope (TEM). Hydrogenated block copolymers were found to have more finely dispersed microphase‐separated structures than those of the unhydrogenated block copolymers with the same CHD/Bd ratios through the use of TEM and the small‐angle X‐ray scattering (SAXS) technique. Those results indicated that the segregation strength between the PCHE block sequence and the PEB block sequence increased, depending on hydrogenation of the unhydrogenated precursor. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 13–22, 2001     

Three‐arm star block copolymers of aromatic polyether and polystyrene from chain‐growth condensation polymerization,atom transfer radical polymerization,and click reaction

Well‐defined (AB)₃ type star block copolymer consisting of aromatic polyether arms as the A segment and polystyrene (PSt) arms as the B segment was prepared using atom transfer radical polymerization (ATRP), chain‐growth condensation polymerization (CGCP), and click reaction. ATRP of styrene was carried out in the presence of 2,4,6‐tris(bromomethyl)mesitylene as a trifunctional initiator, and then the terminal bromines of the polymer were transformed to azide groups with NaN₃. The azide groups were converted to 4‐fluorobenzophenone moieties as CGCP initiator units by click reaction. However, when CGCP was attempted, a small amount of unreacted initiator units remained. Therefore, the azide‐terminated PSt was then used for click reaction with alkyne‐terminated aromatic polyether, obtained by CGCP with an initiator bearing an acetylene unit. Excess alkyne‐terminated aromatic polyether was removed from the crude product by means of preparative high performance liquid chromatography (HPLC) to yield the (AB)₃ type star block copolymer (M_n = 9910, M_w/M_n = 1.10). This star block copolymer, which contains aromatic polyether segments with low solubility in the shell unit, exhibited lower solubility than A₂B or AB₂ type miktoarm star copolymers. In addition, the obtained star block copolymer self‐assembled to form spherical aggregates in solution and plate‐like structures in film. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Photoluminescent properties of poly(p‐phenylene vinylene thiophene‐co‐siloxane)

A new p‐phenylene–vinylene–thiophene‐based siloxane block copolymer has been synthesized. The copolymer consists of alternating rigid and flexible blocks. The rigid blocks are composed of phenylene–vinylene–thiophene‐based units, and the flexible blocks are derived from 1,3‐dialkyldisiloxane units. The former component acts as the chromophore, and allows fine tuning of band gap for blue‐light emission, while the latter imparts good solubility of the copolymer in organic solvents, and thus, should enhance processibility of the resulting copolymer. The thermal properties of the copolymer have been characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The photoluminescence (PL) of the copolymer in solution and in cast film has been studied. The effects of concentration on the PL intensity of the new copolymer in polymer blends with poly(methyl methacrylate) (PMMA) and poly(vinyl carbazole) (PVK) have also been described. Efficient energy transfer from PVK to the new block copolymer in the blended film was observed. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1450–1456, 2000     

Controlled synthesis of trifluoropropylmethylsiloxane–dimethylsiloxane gradient copolymers by anionic ROP of cyclotrisiloxanes

Kinetics of the anionic ring opening copolymerization of 2,4,6‐tris(3,3,3‐trifluoropropyl)‐2,4,6‐trimethylcyclotrisiloxane (F₃) with hexamethylcyclotrisiloxane (D₃) was studied in THF using BuLi as the initiator. The apparent reactivity ratios were estimated by computer simulation to r = 0.10 ± 0.02, r = 51.8 ± 5.5, which were used to predict the copolymer composition. As a result of so much different reactivities, simultaneous copolymerization leads to copolymers of blocky structure containing a narrow intermediate fragment with gradient distribution of siloxane units. Polymers having more uniform distribution of the trifluoropropyl groups along the chain were obtained by the semibatch process, adding F₃ to the polymerization of less reactive D₃. The resulted copolymers were characterized by SEC chromatography, ²⁹Si NMR, DSC, DMA, and SAXS. Thermal and mechanical properties of the copolymers obtained by simultaneous copolymerization were similar to those of block copolymers. Only the copolymers obtained by semibatch method showed properties typical for gradient copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1204–1216, 2009     

Synthesis,dynamic light scattering,and luminescence properties of copolymers containing iridium(III) bisterpyridine in the side chain

Supramolecular block‐random copolymers containing [Ir(terpy)₂]³⁺ in the side chain were synthesized via postfunctionalization of a P(S‐b‐AC_terpy) block copolymer. Absorbance and emission spectra compared to a model compound show that the polymer backbone has a minor effect on the polymer absorbance but produces a larger shift for the phosphorescence signals to higher wavelength. Dynamic light scattering of the metal complex containing copolymer studied in various solvents showed monomodal aggregation with decreasing aggregate size as the solvent dielectric constant increased. The copolymer precursor P(S‐b‐AC_terpy) shows multimodal aggregation in different solvents with the major population consisting of single chains. This difference in behavior between the two polymers is attributed to the electrolytic nature of the complex and the amphiphilicity induced by the charged metal complex. Supramolecular copolymers like these will continue to have interesting self‐organizational properties and may find applications in multicomponent systems for photoinduced charge separation processes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1109–1121, 2007     

Annealing effect on performance and morphology of photovoltaic devices based on poly(3‐hexylthiophene)‐b‐poly(ethylene oxide)

Novel block copolymers, poly(3‐hexylthiophene)‐b‐poly(ethylene oxide) (P3HT‐b‐PEO) were synthesized via Suzuki coupling reaction of P3HT and PEO homopolymers. The copolymers were characterized by NMR, gel permeation chromatography, differential scanning calorimeter, and UV–vis measurements. A series of devices based on the block copolymers with a fullerene derivative were evaluated after thermal or solvent annealing. The device using P3HT‐b‐PEO showed higher efficiency than using P3HT blend after thermal annealing. Phase‐separated structures in the thin films of block copolymer blends were investigated by atomic force microscopy to clarify the relationship between morphologies constructed by annealing and the device performance. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Poly(3‐hexyl thiophene)‐b‐poly(N‐isopropyl acrylamide): Synthesis and its composition dependent structural,solubility, thermoresponsive,electrochemical, and electronic properties

Conjugated block copolymers consisting of poly(3‐hexyl thiophene) (P3HT) and a thermoresponsive polymer poly(N‐isopropyl acrylamide) (PNIPAM) with varying composition have been synthesized by facile click reaction between alkyne terminated P3HT and azide terminated PNIPAM. The composition‐dependent solubility, thermoresponsive property in water, phase behavior, electrochemical, optical, and electronic properties of the block copolymers were systematically investigated. The block copolymers with higher volume fraction of PNIPAM form thermoresponsive spherical micelles with P3HT‐rich crystalline cores and PNIPAM coronas. Both X‐ray and atomic force microscopic studies indicated that the blocks copolymers showed well‐defined microphase separated nanostructures and the structure depended on the composition of the blocks. The electrochemical study of the block copolymers clearly demonstrated that the extent of charge transport through the block copolymer thin film was similar to P3HT homopolymer without any significant change in the band gap. The block copolymers showed improved or similar charge carrier mobility compared with the pure P3HT depending on the composition of the block copolymer. These P3HT‐b‐PNIPAM copolymers were interesting for fabrication of optoelectronic devices capable of thermal and moisture sensing as well as for studying the thermoresponsive colloidal structures of semiconductor amphiphilic systems. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1785–1794