Synthesis of amphiphilic block copolymer consisting of glycopolymer and poly(l‐lactide) and preparation of sugar‐coated polymer aggregates

The block glycopolymer, poly(2‐(α‐d ‐mannopyranosyloxy)ethyl methacrylate)‐b‐poly(l ‐lactide) (PManEMA‐b‐PLLA), was synthesized via a coupling approach. PLLA having an ethynyl group was successfully synthesized via ring‐opening polymerization using 2‐propyn‐1‐ol as an initiator. The ethynyl functionality of the resulting polymer was confirmed by MALDI‐TOF mass spectroscopy. In contrast, PManEMA having an azide group was prepared via AGET ATRP using 2‐azidopropyl 2‐bromo‐2‐methylpropanoate as an initiator. The azide functionality of the resulting polymer was confirmed by IR spectroscopy. The Cu(I)‐catalyzed 1,3‐dipolar cycloaddition between PLLA and PManEMA was performed to afford PManEMA‐b‐PLLA. The block structure was confirmed by ¹H NMR spectroscopy and size exclusion chromatography. The aggregating properties of the block glycopolymer, PManEMA_16k‐b‐PLLA_6.4k (M _n,PManEMA = 16,000, M _n,PLLA = 6400) was examined by ¹H NMR spectroscopy, fluorometry using pyrene, and dynamic light scattering. The block glycopolymer formed complicated aggregates at concentrations above 21 mg·L^?1 in water. The d ‐mannose presenting property of the aggregates was also characterized by turbidimetric assay using concanavalin A. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 395–403     

Synthesis and characterization of pH sensitive poly(glycidol)‐b‐poly(4‐vinylpyridine) block copolymers

Block copolymers of poly(glycidol)‐b‐poly(4‐vinylpyridine) were obtained by ATRP of 4‐vinylpyridine initiated by ω‐(2‐chloropropionyl) poly(glycidol) macroinitiators. By changing the monomer/macroinitiator ratio in the synthesis polymers with varied P4VP/PGl molar ratio were obtained. The obtained block copolymers showed pH sensitive solubility. It was found that the linkage of a hydrophilic poly(glycidol) block to a P4VP influenced the pK_a value of P4VP. DLS measurements showed the formation of fully collapsed aggregates exceeding pH 4.7. Above this pH values the collapsed P4VP core of the aggregates was stabilized by a surrounding hydrophilic poly(glycidol) corona. The size of the aggregates depended significantly upon the composition of the block copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1782–1794, 2009     

Synthesis and characterization of poly(methyl methacrylate)‐block‐poly(methylphenylsilane)‐ block‐poly(methyl methacrylate) by atom transfer radical polymerization

ABA block copolymers of methyl methacrylate and methylphenylsilane were synthesized with a methodology based on atom transfer radical polymerization (ATRP). The reaction of samples of α,ω‐dihalopoly(methylphenylsilane) with 2‐hydroxyethyl‐2‐methyl‐2‐bromoproprionate gave suitable macroinitiators for the ATRP of methyl methacrylate. The latter procedure was carried out at 95 °C in a xylene solution with CuBr and 2,2‐bipyridine as the initiating system. The rate of the polymerization was first‐order with respect to monomer conversion. The block copolymers were characterized with ¹H NMR and ¹³C NMR spectroscopy and size exclusion chromatography, and differential scanning calorimetry was used to obtain preliminary evidence of phase separation in the copolymer products. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 30–40, 2003     

AB2‐type amphiphilic block copolymers composed of poly(ethylene glycol) and poly(N‐isopropylacrylamide) via single‐electron transfer living radical polymerization: Synthesis and characterization

Novel AB₂‐type amphiphilic block copolymers of poly(ethylene glycol) and poly(N‐isopropylacrylamide), PEG‐b‐(PNIPAM)₂, were successfully synthesized through single‐electron transfer living radical polymerization (SET‐LRP). A difunctional macroinitiator was prepared by esterification of 2,2‐dichloroacetyl chloride with poly(ethylene glycol) monomethyl ether (PEG). The copolymers were obtained via the SET‐LRP of N‐isopropylacrylamide (NIPAM) with CuCl/tris(2‐(dimethylamino)ethyl)amine (Me₆TREN) as catalytic system and DMF/H₂O (v/v = 3:1) mixture as solvent. The resulting copolymers were characterized by gel permeation chromatography and ¹H NMR. These block copolymers show controllable molecular weights and narrow molecular weight distributions (PDI < 1.15). Their phase transition temperatures and the corresponding enthalpy changes in aqueous solution were measured by differential scanning calorimetry. As a result, the phase transition temperature of PEG₄₄‐b‐(PNIPAM₅₅)₂ is similar to that in the case of PEG₄₄‐b‐PNIPAM₁₁₀; however, the corresponding enthalpy change is much lower, indicating the significant influence of the macromolecular architecture on the phase transition. This is the first study into the effect of macromolecular architecture on the phase transition using AB₂‐type amphiphilic block copolymer composed of PEG and PNIPAM. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4420–4427, 2009     

Synthesis and characterization of six‐arm star polystyrene‐block‐poly (3‐hexylthiophene) copolymer by combination of atom transfer radical polymerization and click reaction

A novel six‐arm star block copolymer comprising polystyrene (PS) linked to the center and π‐conjugated poly (3‐hexylthiophene) (P3HT) was successfully synthesized using a combination of atom transfer radical polymerization (ATRP) and click reaction. First, star‐shaped PS with six arms was prepared via ATRP of styrene with the discotic six‐functional initiator, 2,3,6,7,10,11‐hexakis(2‐bromoisobutyryloxy)triphenylene. Next, the terminal bromides of the star‐shaped PS were substituted with azide groups. Afterward, the six‐arm star block copolymer PS‐b‐P3HT was prepared using the click coupling reaction of azide‐terminated star‐shaped PS with alkynyl‐terminated P3HT. Various techniques including ¹H NMR, Fourier‐transform infrared and size‐exclusion chromatography were applied to characterize the chemical structures of the intermediates and the target block copolymers. Their thermal behaviors and optical properties were investigated using differential scanning calorimetry and UV–vis spectroscopy. Moreover, atomic force microscopy (AFM) was utilized to observe the morphology of the star block copolymer films. In comparison with two linear diblock copolymer counterparts, AFM results reveal the effect of the star block copolymer architecture on the microphase separation‐induced morphology in thin films. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and solvent‐dependent micellization of the amphiphilic block copolymer poly(styreneboronic acid)‐block‐polystyrene

The amphiphilic organoboron block copolymer poly (styreneboronic acid)‐block‐polystyrene ( PSBA‐b‐PS ) has been prepared through a postpolymerization modification route from the silicon‐functionalized block copolymer poly(4‐trimethylsilylstyrene)‐block‐polystyrene ( PSSi‐b‐PS ). PSBA‐b‐PS is obtained through highly selective reaction of PSSi‐b‐PS with BBr₃ at room temperature and subsequent hydrolysis of the BBr₂‐functionalized intermediate. Transmission electron microscopy studies demonstrate that PSBA‐b‐PS undergoes pH dependent micellization in aqueous solution. Different morphologies could be realized by using different mixtures of water and organic solvents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2438–2445, 2010     

新型线状-树枝状两亲嵌段共聚物的合成

本文设计合成了一系列由不同链长的聚丙烯酸(PAA)为亲水嵌段和不同代数聚苄醚树枝体(Dendr.PBE)为疏水嵌段的杂化共聚物(PAA-Dendr.PBE)。     

Synthesis of a novel liquid crystal rod–coil star block copolymer consisting of poly(methyl methacrylate) and poly{2,5‐bis[(4‐methoxy‐phenyl)oxycarbonyl] styrene} via atom transfer radical polymerization

A bromine capped star‐shaped poly(methyl methacrylate) (S‐PMMA‐Br) was synthesized with CuBr/sparteine/PT‐Br as a catalyst and initiator to polymerize methyl methacrylate (MMA) according to atom transfer radical polymerization (ATRP). Then, with S‐PMMA‐Br as a macroinitiator, a series of new liquid crystal rod–coil star block copolymers with different molecular weights and low polydispersity were obtained by this method. The block architecture {coil‐conformation of the MMA segment and rigid‐rod conformation of 2,5‐bis[(4‐methoxyphenyl)oxycarbonyl] styrene segment} of the four‐armed rod–coil star block copolymers were characterized by ¹H NMR. The liquid‐crystalline behavior of these copolymers was studied by differential scanning calorimetry and polarized optical microscopy. We found that the liquid‐crystalline behavior depends on the molecular weight of the rigid segment; only the four‐armed rod–coil star block copolymers with each arm's M_n,_GPC of the rigid block beyond 0.91 × 10⁴ g/mol could form liquid‐crystalline phases above the glass‐transition temperature of the rigid block. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 733–741, 2005     

Synthesis and self‐assembly of amphiphilic brush‐dendritic‐linear poly[poly(ethylene glycol) methyl ether methacrylate]‐b‐ polyamidoamine‐b‐poly(ε‐caprolactone) copolymers

A series of novel amphiphilic brush‐dendritic‐linear poly[poly(ethylene glycol) methyl ether methacrylate]‐b‐polyamidoamine‐b‐poly(ε‐caprolactone) copolymers (PPEGMEMA‐b‐D_m‐b‐PCL) (m = 1, 2, and 3: the generation number of dendron) were synthesized by the combination techniques of click chemistry, atom transfer radical polymerization (ATRP), and ring‐opening polymerization (ROP). The brush‐dendritic copolymers bearing hydrophilic brush PPEGMEMA and hydrophobic dendron polyamidoamine protected by the tert‐butoxycarbonyl (Boc) groups [D_m‐(Boc) (m = 1, 2, and 3)] were for the first time prepared by ATRP of poly(ethylene glycol) methyl ether methacrylate monomer (PEGMEMA) initiated with the dendron initiator, which was prepared from 2′‐azidoethyl‐2‐bromoisobutyrate (AEBIB) and D_m‐(Boc) terminated with a clickable alkyne by click chemistry. Then, the brush‐dendritic copolymers with primary amine groups (PPEGMEMA‐b‐D_m) were obtained from the removal of the protected Boc groups of the brush‐dendritic copolymers in the presence of trifluoroacetic acid. The brush‐dendritic‐linear PPEGMEMA‐b‐D_m‐b‐PCL copolymers were synthesized from ROP of ε‐caprolactone monomer using PPEGMEMA‐b‐D_m as the macroinitiators and stannous octoate as catalyst in toluene at 130 °C. To the best of our knowledge, this is the first report that integrates hydrophilic brush polymer PPEGMEMA with hydrophobic polyamidoamine (PAMAM) dendron and PCL to form amphiphilic brush‐dendritic‐linear copolymers. The amphiphilic brush‐dendritic‐linear copolymers can self‐assemble into spherical micellar structures in aqueous solution. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of a ‐shaped amphiphilic block copolymer by the combination of atom transfer radical polymerization and living anionic polymerization

The functionalization of monomer units in the form of macroinitiators in an orthogonal fashion yields more predictable macromolecular architectures and complex polymers. Therefore, a new ‐shaped amphiphilic block copolymer, (PMMA)₂–PEO–(PS)₂–PEO–(PMMA)₂ [where PMMA is poly(methyl methacrylate), PEO is poly (ethylene oxide), and PS is polystyrene], has been designed and successfully synthesized by the combination of atom transfer radical polymerization (ATRP) and living anionic polymerization. The synthesis of meso‐2,3‐dibromosuccinic acid acetate/diethylene glycol was used to initiate the polymerization of styrene via ATRP to yield linear (HO)₂–PS₂ with two active hydroxyl groups by living anionic polymerization via diphenylmethylpotassium to initiate the polymerization of ethylene oxide. Afterwards, the synthesized miktoarm‐4 amphiphilic block copolymer, (HO–PEO)₂–PS₂, was esterified with 2,2‐dichloroacetyl chloride to form a macroinitiator that initiated the polymerization of methyl methacrylate via ATRP to prepare the ‐shaped amphiphilic block copolymer. The polymers were characterized with gel permeation chromatography and ¹H NMR spectroscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 147–156, 2007     

Solid‐supported synthesis of well‐defined amphiphilic block copolymer from methacrylates

A new facile method for preparation of an amphiphilic block copolymer via a one‐pot sequential atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA) on solid support was developed. As a model homopolymerization for the solid‐supported block copolymerization, ATRPs of MMA and HEMA in toluene and in 2‐butanone/1‐propanol solvent system were carried out, respectively. Crosslinked polystyrene beads bearing 2‐bromoisobutyrate moieties successfully initiated the polymerizations of MMA and HEMA in controlled manner. On the basis of the successful results, the one‐pot synthesis of amphiphilic block copolymer by changing the reaction medium was performed. After the ATRP of MMA in toluene at 90 °C for 1 h, the poly(MMA) formed on the beads were washed by continuous flow of 2‐butanone/1‐propanol under nitrogen with the aid of a glass filter in a U‐shaped glass vessel. Then, 2‐butanone/1‐propanol, copper chloride (I), 2,2′‐bipyridyl, and HEMA were added and heated at 50 °C for 48 h with shaking the vessel, followed by treatment with trifluoroacetic acid to isolate the well‐defined amphiphilic block copolymer, poly(MMA‐b‐HEMA). These demonstrated the feasibility of the present strategy for well‐defined synthesis of amphiphilic block copolymers via a one‐pot procedure. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1990–1997, 2008     

Synthesis of poly(styrene‐block‐tert‐butyl acrylate) star polymers by atom transfer radical polymerization and micellization of their hydrolyzed polymers

A series of poly(styrene‐block‐tert‐butyl acrylate) heteroatom star block copolymers having various block lengths were prepared by atom transfer radical polymerization (ATRP), using an “as synthesized” cynurate modified trifunctional initiator. The structure of the star polymers was confirmed by the characterization of the individual arms resulting from hydrolysis. Amphiphilic poly(styrene‐block‐acrylic acid) star copolymers were further synthesized by hydrolyzing PtBA blocks using anhydrous trifluoroacetic acid. The characterization data are reported from analyses using gel permeation chromatography, infrared, ¹H and ¹³C NMR spectroscopies. The stable micelle solution was prepared by dialyzing the solution of these polymers in N,N‐dimethylformamide against deionized water. The temperature‐induced associating behavior of these amphiphilic star polymers were studied using dynamic laser light scattering spectroscopy. The hydrodynamic diameter of both micelles and unassociated chains were obtained in the same solution using light scattering cumulant's calculation method. The homogeneity and the size distribution of the micelle population in the solution were determined using centrifuge/sedimentation particle size distribution analyzer. Field emission scanning electron microscope was used to visualize the size of the micelles formed and the micellar aggregates. The influence of the temperature on the viscosity of the micelle solution was studied using an Ubbelohde viscometer. Thermodynamics of micellization of these block copolymers were also investigated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6367–6378, 2005     

Synthesis of polystyrene–poly(tert‐butyl methacrylate)–poly(ethylene oxide) triarm star block copolymers

Three alternative routes, using the heterobifunctional macroinitiator technique, have been developed to obtain polystyrene–poly(tert‐butyl methacrylate)–poly(ethylene oxide) triarm star block copolymers. Only the route showing the reverse initiation of tert‐butyl methacrylate on potassium alkoxide leads to the pure star, whereas the other strategies lead to incomplete initiation because of either an increase in the side reactions, such as transesterification, or a decrease in the accessibility toward bulky catalysts. These limits are linked to the particular location of the initiating group at the junction of the two blocks of the copolymer precursor. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1745–1751, 2004     

Synthesis of amphiphilic copolymer brushes possessing alternating poly(methyl methacrylate) and poly(N‐isopropylacrylamide) grafts via a combination of ATRP and click chemistry

We report on the synthesis of well‐defined amphiphilic copolymer brushes possessing alternating poly(methyl methacrylate) and poly(N‐isopropylacrylamide) grafts, poly(PMMA‐alt‐PNIPAM), via a combination of atom transfer radical polymerization (ATRP) and click reaction (Scheme 1 ). Firstly, the alternating copolymerization of N‐[2‐(2‐bromoisobutyryloxy)ethyl]maleimide (BIBEMI) with 4‐vinylbenzyl azide (VBA) affords poly(BIBEMI‐alt‐VBA). Bearing bromine and azide moieties arranged in an alternating manner, multifunctional poly(BIBEMI‐alt‐VBA) is capable of initiating ATRP and participating in click reaction. The subsequent ATRP of methyl methacrylate (MMA) using poly(BIBEMI‐alt‐VBA) as the macroinitiator leads to poly(PMMA‐alt‐VBA) copolymer brush. Finally, amphiphilic poly(PMMA‐alt‐PNIPAM) copolymer brush bearing alternating PMMA and PNIPAM grafts is synthesized via the click reaction of poly(PMMA‐alt‐VBA) with an excess of alkynyl‐terminated PNIPAM (alkynyl‐PNIPAM). The click coupling efficiency of PNIPAM grafts is determined to be ～80%. Differential scanning calorimetry (DSC) analysis of poly(PMMA‐alt‐PNIPAM) reveals two glass transition temperatures (T_g). In aqueous solution, poly(PMMA‐alt‐PNIPAM) supramolecularly self‐assembles into spherical micelles consisting of PMMA cores and thermoresponsive PNIPAM coronas, which were characterized via a combination of temperature‐dependent optical transmittance, micro‐differential scanning calorimetry (micro‐DSC), dynamic and static laser light scattering (LLS), and transmission electron microscopy (TEM). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2608–2619, 2009     

Synthesis of well‐defined 7‐arm and 21‐arm poly(N‐isopropylacrylamide) star polymers with β‐cyclodextrin cores via click chemistry and their thermal phase transition behavior in aqueous solution

The syntheses of well‐defined 7‐arm and 21‐arm poly(N‐isopropylacrylamide) (PNIPAM) star polymers possessing β‐cyclodextrin (β‐CD) cores were achieved via the combination of atom transfer radical polymerization (ATRP) and click reactions. Heptakis(6‐deoxy‐6‐azido)‐β‐cyclodextrin and heptakis[2,3,6‐tri‐O‐(2‐azidopropionyl)]‐β‐cyclodextrin, β‐CD‐(N₃)₇ and β‐CD‐(N₃)₂₁, precursors were prepared and thoroughly characterized by nuclear magnetic resonance and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. A series of alkynyl terminally functionalized PNIPAM (alkyne‐PNIPAM) linear precursors with varying degrees of polymerization (DP) were synthesized via atom transfer radical polymerization (ATRP) of N‐isopropylacrylamide using propargyl 2‐chloropropionate as the initiator. The subsequent click reactions of alkyne‐PNIPAM with β‐CD‐(N₃)₇ and β‐CD‐(N₃)₂₁ led to the facile preparation of well‐defined 7‐arm and 21‐arm star polymers, namely β‐CD‐(PNIPAM)₇ and β‐CD‐(PNIPAM)₂₁. The thermal phase transition behavior of 7‐arm and 21‐arm star polymers with varying molecular weights were examined by temperature‐dependent turbidity and micro‐differential scanning calorimetry, and the results were compared to those of linear PNIPAM precursors. The anchoring of PNIPAM chain terminal to β‐CD cores and high local chain density for star polymers contributed to their considerably lower critical phase separation temperatures (T_c) and enthalpy changes during phase transition as compared with that of linear precursors. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 404–419, 2009     

Synthesis of well‐defined amphiphilic graft copolymer bearing poly(2‐acryloyloxyethyl ferrocenecarboxylate) side chains via successive SET‐LRP and ATRP

A series of well‐defined ferrocene‐based amphiphilic graft copolymers, consisting of poly(N‐isopropylacrylamide)‐b‐poly(ethyl acrylate) (PNIPAM‐b‐PEA) backbone and poly(2‐acryloyloxyethyl ferrocenecarboxylate) (PAEFC) side chains, were synthesized by the combination of single‐electron‐transfer living radical polymerization (SET‐LRP) and atom transfer radical polymerization (ATRP). A new ferrocene‐based monomer, 2‐(acryloyloxy)ethyl ferrocenecarboxylate (AEFC), was prepared first and it can be polymerized via ATRP in a controlled way using methyl 2‐bromopropionate as initiator and CuBr/PMDETA as catalytic system in DMF at 40 °C. PNIPAM‐b‐PEA backbone was synthesized by sequential SET‐LRP of NIPAM and HEA at 25 °C using CuCl/Me₆TREN as catalytic system followed by the transformation into the macroinitiator by treating the pendant hydroxyls with α‐bromoisobutyryl bromide. The targeted well‐defined graft copolymers with narrow molecular weight distributions (M_w/M_n < 1.20) were synthesized via ATRP of AEFC initiated by the macroinitiator. The electro‐chemical behaviors of PAEFC homopolymer and PNIPAM‐b‐(PEA‐g‐PAEFC) graft copolymer were studied by cyclic voltammetry. Micellar properties of PNIPAM‐b‐(PEA‐g‐PAEFC) were investigated by transmission electron microscopy and dynamic light scattering. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4346–4357, 2009     

Preparation of star block copolymers with polystyrene‐block‐poly(ethylene oxide) as side chains on hyperbranched polyglycerol core by combination of ATRP with atom transfer nitroxide radical coupling reaction

The star block copolymers with polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) as side chains and hyperbranched polyglycerol (HPG) as core were synthesized by combination of atom transfer radical polymerization (ATRP) with the “atom transfer nitroxide radical coupling” (“ATNRC”) reaction. The multiarm PS with bromide end groups originated from the HPG core (HPG‐g‐(PS‐Br)_n) was synthesized by ATRP first, and the heterofunctional PEO with α‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy group and ω‐hydroxyl group (TEMPO‐PEO) was prepared by anionic polymerization separately using 4‐hydroxyl‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy (HTEMPO) as parents compound. Then ATNRC reaction was conducted between the TEMPO groups in PEO and bromide groups in HPG‐g‐(PS‐Br)_n in the presence of CuBr and pentamethyldiethylenetriamine (PMDETA). The obtained star block copolymers and intermediates were characterized by gel permeation chromatography, nuclear magnetic resonance spectroscopy, fourier transform‐infrared in detail. Those results showed that the efficiency of ATNRC in the preparation of multiarm star polymers was satisfactory (>90%) even if the density of coupling cites on HPG was high. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6754–6761, 2008     

Atom transfer radical homo‐ and block copolymerization of methyl 1‐bicyclobutanecarboxylate

A non‐olefinic monomer, methyl 1‐bicyclobutanecarboxylate (MBC), was successfully polymerized by the controlled/“living” atom transfer radical polymerization (ATRP) technique, resulting in a well‐defined homopolymer, PMBC, with only cyclobutane ring units in the polymer chain. An AB block copolymer poly(methyl 1‐bicyclobutanecarboxylate)‐b‐polystyrene (PMBC‐b‐PS), having an all‐ring unit segment, was also synthesized with narrow polydispersity and designed number‐average molecular weight in addition to precise end groups. The ¹H NMR spectra, glass‐transition temperature, and thermal stability of PMBC, PMBC‐b‐PS, and PS‐b‐PMBC were investigated. The experimental results showed that the cyclobutane rings in the two block polymers improved their thermal stability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1929–1936, 2002