Libraries of methacrylic acid and oligo(ethylene glycol) methacrylate copolymers with LCST behavior

Homopolymers of methacrylic acid (MAA), monoethyleneglycol methyl ether methacrylate (MEOMA), diethyleneglycol methyl ether methacrylate (MEO₂MA), oligo(ethyleneglycol) methyl ether methacrylate (OEGMA₄₇₅ and OEGMA₁₁₀₀) and oligo(ethyleneglycol) ethyl ether methacrylate (OEGEMA₂₄₆) were synthesized with various chain lengths via reversible addition fragmentation chain transfer (RAFT) polymerization. The homopolymers of MAA, MEOMA and OEGMA₁₁₀₀ did not show any cloud point (CP) in the range of 0–100 °C, whereas at a pH value of 7, the CPs were found to be 20.6, 93.7, and 20.0 °C for p(MEO₂MA), p(OEGMA₄₇₅) and p(OEGEMA₂₄₆), respectively, with an initial monomer to initiator ratio of 50. Furthermore, statistical copolymer libraries of MAA with OEGMA₄₇₅ and OEGMA₁₁₀₀ were prepared. The cloud points of the random copolymers of MAA and OEGMA₄₇₅ were found to be in the range of 20–90 °C; surprisingly, even though the homopolymers of MAA and OEGMA₁₁₀₀ did not exhibit any LCST behavior, the copolymers of these monomers at certain molar ratios (up to 40% OEGMA₁₁₀₀) revealed a double responsive behavior for both temperature and pH. Finally, the cloud points were found to be in the range of 22–98 °C, measured at pH values of 2, 4, and 7, while no cloud point was detected at pH 10. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7138–7147, 2008     

Temperature responsive copolymers of N‐vinylcaprolactam and di(ethylene glycol) methyl ether methacrylate and their interactions with drugs

Poly(N‐vinylcaprolactam) (PVCL) and poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) are well known for their thermoresponsive behavior in aqueous solutions. Indeed, they display lower critical solution temperatures (LCST) in the physiological range, which makes them interesting for biomedical devices and use in drug delivery systems. Homopolymers of N‐vinylcaprolactam and di(ethylene glycol) methyl ether methacrylate as well as copolymers thereof were synthesized by solution and direct miniemulsion polymerizations. The cloud points of the copolymers in aqueous solution were investigated as a function of temperature, comonomer ratio, and in the presence of model pharmaceutical ingredients. By variation of the comonomer ratio, it was possible to control the cloud point temperature between 26 and 35 °C, which was found to be beneficial to attenuate the effect of the drugs that also altered the cloud points. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3308–3313     

Synthesis of di‐ and tri‐tertiary amine containing methacrylic monomers and their (co)polymerization via RAFT

The synthesis, reversible addition‐fragmentation chain transfer (RAFT) (co)polymerization, and aqueous phase behavior of three methacrylic monomers containing two or three pendent tertiary amine functional groups are described. Homopolymerizations were conducted with 1‐methyl‐1‐cyanoethyl dithiobenzoate (CPDB) under bulk conditions following standard RAFT procedures. All three monomers, 1,3‐bis(dimethylamino)propan‐2‐yl methacrylate ( M1 ), 1‐(bis(3‐(dimethylamino)propyl) amino)propan‐2‐yl methacrylate ( M2 ), and 2‐((2‐(2‐(dimethylamino)ethoxy)ethyl) methylamino)ethyl acrylate ( M3 ), polymerized in a controlled manner as evidenced by the kinetic and molecular weight profiles. Homopolymerizations conducted at a lower ratio of CPDB:AIBN proceeded faster than those at a higher ratio. Subsequently, the facile copolymerization behavior of M1 and M3 was demonstrated via the synthesis of a range of statistical copolymers with hexyl and lauryl methacrylate comonomers containing 10–90 mol % hydrophobic comonomer. Finally, the aqueous‐solution characteristics of the M1 – M3 homopolymers were briefly examined. All three homopolymers were shown to undergo phase transitions in aqueous media in response to changes in both temperature and pH. Specifically, 1 wt % solutions of poly M1 were shown to possess an LCST of ～22 °C, that of poly M2 at ～33 °C, and for poly M3 the observed cloud point was ～63 °C. Additionally, all homopolymers became hydrophobic and phase separated at high solution pH. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1877–1890, 2009     

Multistimuli responsive amphiphilic graft poly(ether amine): Synthesis,characterization, and self‐assembly in aqueous solution

We reported that multiresponsive amphiphilic graft poly(ether amine)s (agPEAs) comprised of hydrophilic poly(ethylene oxide) (PEO) and hydrophobic octadecyl alkyl chain as side‐chain were prepared through one‐pot synthesis. In aqueous solution, these obtained agPEAs can self‐assemble into stable nanomicelles, whose aggregation can be controlled by temperature, pH, and ionic strength with tunable cloud point (CP). In the presence of these obtained agPEAs, hydrophobic dye Nile red can be dispersed into aqueous solution and hydrophilic dye methyl orange can be dispersed into nonpolar toluene. The agPEAs are expected to be potential in application such as encapsulation and controlled release of drugs, due to their simple synthesis, amphiphilicity, and multistimuli response. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 327–335, 2010     

Degradable alternating polyperoxides from poly(ethylene glycol)‐substituted styrenic monomers with water solubility and thermoresponsiveness

Water soluble alternating copolymers were prepared by oxidative free radical copolymerization of 4‐vinylbenzyl methoxypoly(oxyethylene) ether (PEGSt) and molecular oxygen at 50 °C. NMR spectroscopy established alternate sequence of PEGSt and peroxy bonds ( O O ) along the polymer main‐chain. The obtained polymers show temperature induced hydrophilic to hydrophobic phase separation, confirmed by UV‐visible spectroscopy and dynamic light scattering. The cloud point temperature (T_CP) of the polymers can be tuned by changing the chain length of side‐chain poly(ethylene oxide) and incorporation of hydrophobic methyl methacrylate in the copolyperoxides. Exothermic degradation of these polyperoxides was confirmed by differential scanning calorimetry and the degradation products have been characterized by electron impact mass spectroscopy. Finally, N,N‐dimethylacrylamide was polymerized in the presence of these polyperoxides in toluene, highlighting their potential as polymeric free radical initiator during polymerization of vinyl monomers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2030–2038     

Core‐shell functional nanospheres for oligonucleotide delivery. III. Stealth nanospheres

Polymethyl methacrylate‐based stealth and functional nanospheres, specifically designed for the reversible adsorption of oligonucleotides (ODN), were prepared by emulsion polymerization of methyl methacrylate in the presence of an ionic comonomer, namely a quaternary ammonium salt of 2‐(dimethylamino)ethyl methacrylate, and a nonionic comonomer, namely a poly(ethylene glycol) methacrylate. The nanosphere size is substantially affected by the amount of both the nonionic and ionic comonomers. By appropriately adjusting the concentrations of the ionic and nonionic comonomers, the quaternary ammonium group and PEG chain surface densities can be finely tuned. Accordingly, a great variety of core‐shell‐type nanospheres, able to bind ODN and to induce dysopsonic effect, can be obtained. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3347–3354, 2000     

Novel temperature‐responsive water‐soluble copolymers based on 2‐hydroxyethylacrylate and vinyl butyl ether and their interactions with poly(carboxylic acids)

Novel water‐soluble amphiphilic copolymers have been synthesized by free radical copolymerization of 2‐hydroxyethylacrylate with vinyl butyl ether. In water these copolymers exhibit lower critical solution temperature, which depends on the content of hydrophobic vinyl butyl ether units. The interaction between these copolymers and poly(acrylic acid) or poly(methacrylic acid) in aqueous solutions results in formation of interpolymer complexes stabilized by hydrogen bonds and hydrophobic interactions. An increase in hydrophobicity of the copolymers leads to the enhancement of their complex formation ability with respect to poly(acrylic acid) and poly(methacrylic acid). Poly(methacrylic acid) forms stronger complexes with the copolymers when compared with poly(acrylic acid). The complexes exhibit dual sensitivity to pH‐ and temperature and this property may be easily adjusted regulating the strength of interaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 195–204, 2006     

End group polarity and block symmetry effects on cloud point and hydrodynamic diameter of thermoresponsive block copolymers

Thermoresponsive block copolymers are of interest for delivery vehicles in the body. Often an interior domain is designed for the active agent and the exterior domain provides stability in the bloodstream, and may carry a targeting ligand. There is still much to learn about how block sequence and chain end identity affect micelle structure, size, and cloud points. Here, hydrophilic oligo(ethylene glycol) methyl ether acrylate and more hydrophobic di(ethylene glycol) methyl ether methacrylate monomers were polymerized to give amphiphilic block copolymers with amphiphilic chain ends. The block sequence and chain end identity were both controlled by appropriate choice of RAFT chain transfer agents to study the effect of ‘matched’ and ‘mismatched’ chain end polarity with amphiphilic block sequence. The affect of matching or mismatching chain end polarity and block sequence was studied on the hydrodynamic diameter, cloud point, and temperature range of the chain collapse on linear di‐ and triblock copolymers and star diblock polymers. The affects of matching or mismatching chain end polarity were significant with linear diblock copolymers but more complex with triblock and star copolymers. Explanations of these results may help guide others in designing thermoresponsive block copolymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2838–2848     

Multistimuli responsive micelles based on well‐defined amphiphilic comb poly(ether amine) (acPEA)

A series of well‐defined amphiphilic comb poly (ether amine)s (acPEAs) were successfully synthesized through nucleophilic addition/ring‐opening reaction of commercial available poly(propylene glycol) (PPO) diglycidyl ether and Jeffamine L100, followed by esterification of hydroxyl groups in backbone by alkyl carboxylic acid with different chain length. acPEAs are comprised of hydrophilic short PEO chains and hydrophobic alkyl chains as comb chains, which are grafted on PPO backbone alternately to form well‐defined structure. With the very low critical micelle concentration (CMC) of around 3.0 × 10^?3 g/L, the obtained acPEAs can self‐assemble into stable nanomicelles, whose aggregation is responsive to temperature, pH, and ionic strength with tunable cloud point (CP). The CP of acPEAs' aqueous solution increases with the decrease of the length of graft alkyl chains, the decrease of pH value, and the decrease of ionic strength. A transition behavior in the responsive aggregation of micelles formed by acPEA8 and acPEA10 in aqueous solution, especially at low pH value (<7.0), was observed, which was also revealed by DLS results. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3468–3475, 2010     

A comparative study of the stimuli‐responsive properties of DMAEA and DMAEMA containing polymers

Reversible addition‐fragmentation chain transfer copolymerization of dimethylaminoethyl acrylate (DMAEA) and methyl acrylate (MA) and their methacrylate counterparts (MMA) has been performed with good control over molecular weight and polydispersity. A screening in composition of copolymers has been performed from 0 to 75% of MA (or MMA). The behavior of these pH and temperature‐sensitive copolymers has been studied in aqueous solution by measuring the cloud point (CP) and the acid dissociation constants (pK_a). The higher incorporation of the hydrophobic monomer in the copolymer resulted in an increase in the pK_a values due to the larger distance between charges thus facilitating the protonation of adjacent nitrogens for both, the acrylate and methacrylate derivatives. The CP behavior of the copolymers has been studied in pure water and the CP values have been found to be irreproducible for the acrylate polymers, as a consequence of the self‐hydrolysis of DMAEA. Hence, kinetic studies have been performed to quantify the degree of self‐hydrolysis at different temperatures and polymer concentrations to explore the full potential and application of these versatile polymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3333–3338     

Hydrophobicity of fluoro‐containing physical crosslinkage domains in hydrophobically modified poly(acrylic acid) gels

A series of hydrophobically modified poly(acrylic acid) gels were prepared by the radical copolymerization of acrylic acid and small amounts of hydrophobic comonomers, 2‐(N‐ethylperfluorooctane‐sulfoamido)ethyl methacrylate and lauryl acrylate, in tert‐butanol. The effects of the fractions and species of hydrophobes on hydrophobic association were determined. The hydrophobic association within the hydrophobically modified gels was proven with measurements of swelling and fluorescence as well as Fourier transform infrared spectroscopy. Fluorocarbon‐modified hydrogels showed stronger hydrophobicity than hydrocarbon‐modified hydrogels. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1236–1244, 2002     

Thermodynamic analysis of the reaction‐induced phase separation of solutions of random copolymers of methyl methacrylate and N,N‐dimethylacrylamide in the precursors of a polythiourethane network

Poly(methyl methacrylate) and random copolymers of methyl methacrylate (MMA) and N,N‐dimethylacrylamide (DMA) containing 7.5, 15, or 20 wt % DMA were dissolved in a stoichiometric mixture of m‐xylylene diisocyanate and 4‐mercaptomethyl‐3,6‐dithia‐1,8‐octanedithiol, precursors of a polythiourethane network. Phase separation, which took place during polymerizations at 60, 90, and 120 °C, exhibited a lower critical solution temperature behavior. The cloud‐point conversions, which were determined by the iodometric titration of free thiol groups of samples chilled in ice at the cloud point, increased with the weight fraction of DMA in the random copolymer. This could be used to control the cloud‐point conversion and determine the characteristic size of the dispersed domains. A thermodynamic analysis was performed with the Flory–Huggins equation, taking into account the polydispersities of both the thermoplastic and thermoset polymers and using an interaction parameter depending on the temperature and on the three binary interaction energies. A reasonable fitting of the experimental curves was obtained with negative values for the interaction energies of the MMA–thermoset and DMA–thermoset pairs and with a positive value for the MMA–DMA pair. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2821–2827, 2006     

Synthesis of double hydrophilic graft copolymer containing poly(ethylene glycol) and poly(methacrylic acid) side chains via successive ATRP

A well‐defined double hydrophilic graft copolymer, with polyacrylate as backbone, hydrophilic poly(ethylene glycol) and poly(methacrylic acid) as side chains, was synthesized via successive atom transfer radical polymerization followed by the selective hydrolysis of poly(methoxymethyl methacrylate) side chains. The grafting‐through strategy was first used to prepare poly[poly(ethylene glycol) methyl ether acrylate] comb copolymer. The obtained comb copolymer was transformed into macroinitiator by reacting with lithium diisopropylamine and 2‐bromopropionyl chloride. Afterwards, grafting‐from route was employed for the synthesis of poly[poly(ethylene glycol) methyl ether acrylate]‐g‐poly(methoxymethyl methacrylate) amphiphilic graft copolymer. The molecular weight distribution of this amphiphilic graft copolymer was narrow. Poly(methoxymethyl methacrylate) side chains were connected to polyacrylate backbone through stable C? C bonds instead of ester connections. The final product, poly[poly(ethylene glycol) methyl ether acrylate]‐g‐poly(methacrylate acid), was obtained by selective hydrolysis of poly(methoxymethyl methacrylate) side chains under mild conditions without affecting the polyacrylate backbone. This double hydrophilic graft copolymer was found be stimuli‐responsive to pH and ionic strength. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4056–4069, 2008     

Preparation of novel alkaline pH‐responsive copolymers for the formation of recyclable aqueous two‐phase systems and their application in the extraction of lincomycin

Aqueous two‐phase systems have potential industrial application in bioseparation and biocatalysis engineering; however, their practical application is limited primarily because the copolymers involved in the formation of aqueous two‐phase systems cannot be recovered. In this study, two novel alkaline pH‐responsive copolymers were synthesized and examined for the extraction of lincomycin. The two copolymers could form a novel alkaline aqueous two‐phase systems when their concentrations were both 6% w/w and the pH was 8.4(±0.1)–8.7(±0.1). One copolymer was synthesized using acrylic acid, 2‐(dimethylamino)ethyl methacrylate, and butyl methacrylate as monomers. Moreover, 98.8% of the copolymer could be recovered by adjusting the solution pH to its isoelectric point (pH 6.29). The other copolymer was synthesized using the monomers methacrylic acid, 2‐(dimethylamino)ethyl methacrylate, and methyl methacrylate. In this case, 96.7% of the copolymer could be recovered by adjusting the solution pH to 7.19. The optimal partition coefficient of lincomycin was 0.17 at 30°C in the presence of 10 mM KBr and 5.5 at 40°C in the presence of 80 mM Ti(SO₄)₂ using the novel alkaline aqueous two‐phase systems.     

Novel temperature‐ and pH‐responsive graft copolymers composed of poly(L‐glutamic acid) and poly(N‐isopropylacrylamide)

A series of novel temperature‐ and pH‐responsive graft copolymers, poly(L ‐glutamic acid)‐g‐poly(N‐isopropylacrylamide), were synthesized by coupling amino‐semitelechelic poly(N‐isopropylacrylamide) with N‐hydroxysuccinimide‐activated poly(L ‐glutamic acid). The graft copolymers and their precursors were characterized, by ESI‐FTICR Mass Spectrum, intrinsic viscosity measurements and proton nuclear magnetic resonance (¹H NMR). The phase‐transition and aggregation behaviors of the graft copolymers in aqueous solutions were investigated by the turbidity measurements and dynamic laser scattering. The solution behavior of the copolymers showed dependence on both temperature and pH. The cloud point (CP) of the copolymer solution at pH 5.0–7.4 was slightly higher than that of the solution of the PNIPAM homopolymer because of the hydrophilic nature of the poly(glutamic acid) (PGA) backbone. The CP markedly decreased when the pH was lowered from 5 to 4.2, caused by the decrease in hydrophilicity of the PGA backbone. At a temperature above the lower critical solution temperature of the PNIPAM chain, the copolymers formed amphiphilic core‐shell aggregates at pH 4.5–7.4 and the particle size was reduced with decreasing pH. In contrast, larger hydrophobic aggregates were formed at pH 4.2. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4140–4150, 2008     

Control of thermoresponsivity of biocompatible poly(trimethylene carbonate) with direct introduction of oligo(ethylene glycol) under various circumstances

Poly(trimethylene carbonate) (PTMC) is a well‐known biodegradable polymer with good biocompatible properties which make it suitable for biomedical applications. Poly(5‐[2‐{2‐(2‐methoxyethoxy)ethyoxy}‐ethoxymethyl]‐5‐methyl‐1,3‐dioxa‐2‐one) (PTMC‐MOE3OM) and copolymers, bearing oligo ethylene glycol (OEG) at the side chain of PTMC backbone, were selected to investigate the cloud point behavior by solvents such as PBS, water, 10% ethanol solution and various ionic strengths. A pH‐responsive copolymer, poly(TMCM‐MOE3OM‐co‐(5‐methyl‐5‐carboxylic‐1,3‐dioxane‐2‐one)) as carboxylic acid carbonate showed a decreased critical temperature at pH 2. Photo‐responsive copolymer, poly(TMCM‐MOE3OM‐co‐coumarin derivatives) bearing 1% and 10% of photo‐induced molecules (7‐[(5‐(5‐methyl‐1,3‐dioxa‐2‐one)methoxy)]‐methoxy coumarin (TMCM‐coumarin)) exhibited a low cloud point because of the hydrophobic moieties. Meanwhile, alternative coumarin polymer including 2% of 4‐methyl‐7‐[(5‐(5‐methyl‐1,3‐dioxa‐2‐one)methoxy)butoxy)]‐methoxy coumarin (TMCM‐4‐methyl‐coumarin) has been successfully synthesized and copolymerized as a novel molecule. The various combinations of monomers were studied and the significant properties were determined via external triggers after copolymerization. This study showed basically synthetic progress toward designs and trivial rationalization of thermoresponsive copolymers close to body temperature. At present, various pendant groups as side part affect to the lower critical solution temperature (LCST) and biodegradable polymer in order to utilize the actual external stimuli application. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3466–3474     

Physicochemical characterization of the thermo‐induced self‐assembly of thermo‐responsive PDMAEMA‐b‐PDEGMA copolymers

Diblock copolymers of poly[2‐(dimethylamino)ethyl methacrylate]‐block‐poly[di(ethylene glycol) methyl ether methacrylate], PDMAEMA‐b‐PDEGMA, were synthesized by reversible addition–fragmentation chain transfer polymerization. The block ratio was varied to study the influence on the lower critical solution temperature and the corresponding phase transition in water. Therefore, turbidimetry, differential scanning calorimetry (DSC), dynamic light scattering (DLS), and laser Doppler velocimetry were applied. Additionally, asymmetric flow field‐flow fractionation (AF4) coupled to DLS and multiangle laser light scattering (MALLS) was established as an alternative route to characterize these systems in terms of molar mass of the polymer chain and size of the colloids after the phase transition. It was found that AF4–MALLS allowed accurate determination of molar masses in the studied range. Nevertheless, some limitations were observed, which were critically discussed. The cloud point and phase transition of all materials, as revealed by turbidimetry, could be confirmed by DSC. For block copolymers with block ratios in the range of 50:50, a thermo‐induced self‐assembly into micellar and vesicular structures with hydrodynamic radii (R_h) of around 25 nm was observed upon heating. At higher temperatures, a reordering of the self‐assembled structures could be detected. The thermo‐responsive behavior was further investigated in dependence of pH value and ionic strength. Variation of the pH value mainly influences the solubility of the PDMAEMA segment, where a decrease of the pH value increases the transition temperature. An increase of ionic strength leads to a reduction of the cloud point due to the screening of electrostatic interactions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 924–935     

Alkali metal salt‐catalyzed aldol addition of dimethylsilyl enolate on a polyether structure

The aldol addition of dimethylsilyl enolates to aldehydes with alkali metal salt catalysts was examined. Several kinds of polyether derivatives were employed as solid solvents without a liquid one. In the presence of the polymer (Gr) obtained from poly(ethylene glycol) methyl ether methacrylate (PEGMA) or the crosslinked derivatives (GLs) from PEGMA, the aldol addition proceeded efficiently and yielded the product. The effective catalyst was lithium bromide for Gr and potassium bromide for GLs. The crosslinked polyether GLs were easily separated from the reaction mixture by simple filtration, which was preferable to simplifying the treatments of the reaction. The results demonstrated that the presence of polyether structures provided a favorable reaction environment and enabled the reaction under solvent‐free conditions. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2075–2084, 2005     

Metallocene/methylaluminoxane‐catalyzed copolymerizations of oxygen‐functionalized long‐chain olefins with ethylene

Copolymerizations of ethylene with 10‐undecen‐1‐ol, 10‐undecenyl methyl ether, 10‐undecenyl trimethyl silyl ether, and 1‐undecene were performed with rac‐ethylene‐bis(1‐indenyl)zirconium dichloride as a catalyst and methylaluminoxane as a cocatalyst. All three oxygen‐functional comonomers copolymerized with ethylene, although the activity of the catalyst decreased considerably compared with the homopolymerization of ethylene. The conversions of the comonomers varied from 17 to 40%, depending on the amount of comonomer in the feed. Under the same conditions, the conversion of 1‐undecene was 50–75%. The incorporation (0.7–3.6 mol %, depending on the feed) and the effect on the activity of the catalyst were on the same level for all the functional comonomers, which indicates that trimethylsilyl or methyl groups do not act as effective protecting groups for oxygen atoms. According to NMR and Fourier transform infrared analyses, the final functional group in the copolymers of the trimethylsilyl ether comonomer was hydroxyl. In contrast, the methyl ether group remained untouched in the copolymer, which suggests that the formation of aluminum alkoxides via a reaction with a cocatalyst is not a prerequisite for comonomer incorporation. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1966–1971, 2000     

Thermal Properties of Oligo(2-ethyl-2-oxazoline) Containing Comb and Graft Copolymers and their Aqueous Solutions

Summary: The cationic ring opening polymerization of 2-ethyl-2-oxazoline (EtOx) was applied for the synthesis of methacrylate end-functionalized well-defined macromonomers that could be polymerized in a controlled manner using reversible addition-fragmentation chain transfer polymerization. The obtained comb polymers revealed lower critical solution temperature behavior in aqueous solution. The cloud points of these solutions could be tuned in a range from 35 °C to 85 °C by the incorporation of hydrophobic methyl methacrylate comonomer in varying amounts into the graft copolymers whereas copolymerization with methacrylic acid rendered temperature and pH sensitive copolymers. Thermo-gravimetric analysis showed a two-step decomposition of the graft copolymers and differential scanning calorimetry revealed glass transition temperatures that are significantly lowered in comparison to linear PEtOx.