Novel nonionic polymerisable surfactants based on sulfoxides. 1. Monomer synthesis and general surfactant behaviour

The synthesis, surface activity, and micellisation of a series of new nonionic polymerisable surfactants, often referred to as surfmers, are described. These monomers bear terminal vinyl groups or acrylic esters, and the nonionic sulfoxide moiety. Compared to many other nonionic hydrophilic fragments, the sulfoxide group behaves as a strongly hydrophilic fragment of small volume, that can balance up to an acryloyloxyundecyl hydrophobic chain. The incorporation of the polar acrylate moiety at the end of the hydrophobic chain seems to confer surfactant properties similar to the ones of bola amphiphiles to the monomers. Received: 22 March 2001 Accepted: 11 August 2001     

Non-ionic amphiphilic block copolymers by RAFT-polymerization and their self-organization

Water-soluble, amphiphilic diblock copolymers were synthesized by reversible addition fragmentation chain transfer polymerization. They consist of poly(butyl acrylate) as hydrophobic block with a low glass transition temperature and three different nonionic water-soluble blocks, namely, the classical hydrophilic block poly(dimethylacrylamide), the strongly hydrophilic poly(acryloyloxyethyl methylsulfoxide), and the thermally sensitive poly(N-acryloylpyrrolidine). Aqueous micellar solutions of the block copolymers were prepared and characterized by static and dynamic light scattering analysis (DLS and SLS). No critical micelle concentration could be detected. The micellization was thermodynamically favored, although kinetically slow, exhibiting a marked dependence on the preparation conditions. The polymers formed micelles with a hydrodynamic diameter from 20 to 100 nm, which were stable upon dilution. The micellar size was correlated with the composition of the block copolymers and their overall molar mass. The micelles formed with the two most hydrophilic blocks were particularly stable upon temperature cycles, whereas the thermally sensitive poly(N-acryloylpyrrolidine) block showed a temperature-induced precipitation. According to combined SLS and DLS analysis, the micelles exhibited an elongated shape such as rods or worms. It should be noted that the block copolymers with the most hydrophilic poly(sulfoxide) block formed inverse micelles in certain organic solvents.     

Synthesis of well‐defined macromonomers and comb copolymers from polymers made by atom transfer radical polymerization

Poly(n‐butyl acrylate) macromonomers with predetermined molecular weights (1300 < number‐average molecular weight < 23,000) and low polydispersity indices (<1.2) were synthesized from bromine‐terminated atom transfer radical polymerization polymers via end‐group substitution with acrylic acid and methacrylic acid. These macromonomers, having a high degree of end‐group functionalization (>90%), were radically homopolymerized to obtain comb polymers. A high macromonomer concentration, combined with a low radical flux, was needed to obtain a high conversion of the macromonomers and a reasonable degree of polymerization. By the traditional radical copolymerization of the hydrophobic macromonomers with the hydrophilic monomer N,N‐dimethylaminoethyl methacrylate (DMAEMA), amphiphilic comb copolymers were obtained. The conversions of the macromonomers and comonomer were almost quantitative under optimized reaction conditions. The molecular weights were high (number‐average molecular weight ≈70,000), and the molecular weight distribution was broad (polydispersity index ≈ 3.5). Kinetic measurements showed simultaneous decreases in the macromonomer and DMAEMA concentrations, indicating a relatively homogeneous composition of the comb copolymers over the whole molecular weight range. This was supported by preparative size exclusion chromatography. The copolymerization of poly(n‐butyl acrylate) macromonomers with other hydrophilic monomers such as acrylic acid or N,N‐dimethylacrylamide gave comb copolymers with multimodal molecular weight distributions in size exclusion chromatography and extremely high apparent molecular weights. Dynamic light scattering showed a heterogeneous composition consisting of small (6–9 nm) and large (23–143 nm) particles, probably micelles or other type of aggregates. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3425–3439, 2003     

Thermoresponsive amphiphilic symmetrical triblock copolymers with a hydrophilic middle block made of poly(N-isopropylacrylamide): synthesis, self-organization, and hydrogel formation

Several series of symmetrical triblock copolymers were synthesized by the reversible addition fragmentation chain transfer method. They consist of a long block of poly(N-isopropylacrylamide) as hydrophilic, thermoresponsive middle block, which is end-capped by two small strongly hydrophobic blocks made from five different vinyl polymers. The association of the amphiphilic polymers was studied in dilute and concentrated aqueous solution. The polymer micelles found at low concentrations form hydrogels at high concentrations, typically above 30–35 wt.%. Hydrogel formation and the thermosensitive rheological behavior were studied exemplarily for copolymers with hydrophobic blocks of polystyrene, poly(2-ethylhexyl acrylate), and poly(n-octadecyl acrylate). All systems exhibited a cloud point around 30 °C. Heating beyond the cloud point initially favors hydrogel formation but continued heating results in macroscopic phase separation. The rheological behavior suggests that the copolymers associate into flower-like micelles, with only a small share of polymers that bridge the micelles and act as physical cross-linkers, even at high concentrations.     

Sodium hydride-initiated polymerizations of vinyl monomers in aprotic solvents

Polymerizations of several vinyl monomers at 25°C in aprotic solvents (dimethyl sulfoxide, N,N-dimethylacetamide, and hexamethylphosphoric triamide) using sodium hydride dispersion as initiator yield low to intermediate molecular weight polymers. The molecular weight of the resulting polymer as well as the mode of initiation depends on the monomer and aprotic solvent used. Initiation of polymerization of monomers with available α hydrogens (methyl acrylate, acrylonitrile) involves monomer anion, while initiation of a monomer with no α hydrogen (methyl methacrylate) proceeds by a more complex mechanism. In contrast, initiation of styrene and α-methylstyrene proceeds by dimsyl anion addition to monomer in dimethylsulfoxide. Although the triad tacticities and number-average molecular weights of poly(methyl methacrylate) samples obtained from all three aprotic solvents are nearly the same, poly(methyl methacrylates) prepared in dimethyl sulfoxide and N,N-dimethylacetamide give polymers having polydispersities of ～3, while a very polydisperse polymer is obtained in hexamethylphosphoric triamide.     

Methionine sulfoxide and phosphonate containing double hydrophilic block copolypeptides and their mineralization of calcium carbonate

In effort to address challenges in the efficient synthesis of highly functional block copolypeptides, we report use of a combination of functional monomer polymerization and postpolymerization modification to obtain new double hydrophilic block copolypeptides with desirable properties. We prepared copolymers that contain discrete hydrophilic, nonionic poly(l‐ methionine sulfoxide) and Ca²⁺ ion binding poly(l ‐phosphonohomoalanine) segments. The facile and selective postpolymerization conversion of inexpensive, readily prepared poly(l ‐methionine) segments into nonionic, hydrophilic poly(l ‐methionine sulfoxide) segments reduces the need for use of combinations of protecting groups. The complex copolypeptides prepared using this strategy were able to promote formation of CaCO₃ microspheres with tunable polymorphism. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3707–3712     

Synthesis and radical polymerization of methacrylate endowed with bicyclobis(γ‐butyrolactone) moiety through methylene linker

A series of methacrylates bearing bicyclobis(γ‐butyrolactone) (BBL) moiety were synthesized and radically polymerized to afford the corresponding poly(methacrylate)s bearing BBL moiety in the side chain, with expecting that the high polarity and rigidity of BBL would be inherited by the polymers. The resulting polymers were soluble in polar aprotic solvents such as dimethyl sulfoxide and N,N‐dimethylformamide because of the high polarity of the BBL moiety. The glass transition temperatures (T_g) of the polymers depended on the length of methylene linker that tethered the methacrylate and BBL moieties, making the use of shorter linkers lead to higher T_gs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2462–2468     

Versatile cobalt(Salen-NEt2) for aqueous cobalt-mediated radical polymerization

Cobalt-mediated radical polymerization (CMRP) has enabled the polymerization of a wide range of monomers with predictable molecular parameters and well-defined compositions and architectures. However, the synthesis of hydrophilic polymers by CMRP directly in the aqueous phase is still challenging. Herein, a handy cobalt complex was developed to perform CMRP of N-vinylpyrrolidone (NVP), 2-hydroxyethyl acrylate (HEA), and N,N-dimethylacrylamide (DMA) with linearly increased molecular weight, low polydispersity values, and smoothly shifted gel permeation chromatography (GPC) traces. The chain extensions of NVP, HEA, and DMA revealed the well chain-end fidelity for the synthesis of block copolymers. Moreover, the poly(N-vinylpyrrolidone)-block-poly(vinyl acetate) (PVP-b-PVAc) amphiphilic block copolymer colloidal solution was achieved directly in aqueous phase by cobalt-mediated radical polymerization-induced self-assembly (CMR-PISA), forming the nanoparticles consisting of a hydrophilic PVP corona and a hydrophobic PVAc core. This new mediator opens the opportunity for the synthesis of various hydrophilic (co)polymers in an environmentally friendly manner.     

Amine‐Reactive Polymers Synthesized by RAFT Polymerization Using an Azlactone Functional Trithiocarbonate RAFT Agent

A new azlactone‐derived trithiocarbonate is prepared and used as a chain‐transfer agent to mediate the reversible addition‐fragmentation chain transfer (RAFT) polymerization of styrene, ethyl acrylate, and N‐isopropyl acrylamide. Well‐defined polymers with controlled molecular weights (M _n = 1000–7000 g mol⁻¹) and narrow molecular weight distributions (PDI = 1.05–1.10) are thus obtained that retain the azlactone functionality at the chain end. The ability of the resulting end‐functionalized polymers to react quantitatively at room temperature with a stoichiometric amount of amino groups with retention of the thiocarbonylthio moiety is ascertained by using 4‐fluorobenzylamine and allylamine.     

Functional monomers and polymers. CXXI. Methylation and interaction studies on adenine containing polymethacrylate derivatives

Studies of the methylation of polymethacrylate derivatives with adenine bases were made in comparison to those with uracil bases. The polymethacrylate derivatives with adenine bases were methylated by using methyl iodide in dimethyl sulfoxide solution to produce polymers that contained N¹-methyladenine and N¹, N⁶-dimethyladenine units. The products were identified by spectroscopic data and by preparing their model compounds. The methylated polymers obtained were further applied in a study of polymer complex formation with uracil-base polymers.     

Prodendronic polyamines from stable or labile methacrylates obtained by selective Michael addition onto asymmetric diacrylic compounds

A new synthetic strategy for the preparation of methacrylic monomers and polymers carrying acyl β‐amino groups is presented. The approach is based on the Michael addition of aliphatic amines onto asymmetric acrylic/methacrylic compounds, reacting the amine highly selectively with the acrylic unit while leaving the methacrylic moiety unreacted. The corresponding polymers are then obtained by conventional radical polymerization. The use of N,N,N′,N′‐tetraethyldiethylenetriamine (TEDETA) as the secondary amine leads to TEDETA moieties supported on polymeric chains. The new aminopolymers are sensitive to pH and to temperature exhibiting a lower critical solution temperature of between 50 and 90 °C. A further interesting feature of the new approach is that the stability toward hydrolysis of the side β‐amino acyl compounds was found to be dependent on whether an acrylamide or an acrylate is employed as the acrylic group of the asymmetric starting material. The esters exhibit an enhanced sensitivity to hydrolysis, compared to standard aliphatic esters, and decompose releasing a derivative of the amine precursor, within hours or weeks, depending on the pH and temperature conditions. The use of the amides leads to stable polymers when the same experimental conditions are applied. The novel dendronic polyamines have been proven to interact with DNA and to transfect cells with efficiency close to that obtained with polyethyleneimine vectors used as positive controls. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2297–2305     

Thermal degradation of vinylidene chloride/[4-(t-butoxycarbonyloxy)phenyl]methyl acrylate copolymers

Vinylidene chloride polymers containing comonomer units capable of consuming evolved hydrogen chloride to expose good radical-scavenging sites might be expected to display greater thermal stability than similar polymers containing simple alkyl acrylates as comonomer. Incorporation of a comonomer containing the phenyl t-butyl carbonate moiety into a vinylidene chloride polymer has the potential to afford a polymer with pendant groups which might interact with hydrogen chloride to expose phenolic groups. Copolymers of vinylidene chloride with [4-(t-butoxycarbonyloxy)phenyl]methyl acrylate have been prepared, characterized, and subjected to thermal degradation. The degradation has been characterized by thermal and spectroscopic techniques. The degradation of vinylidene chloride/[4-(t-butoxycarbonyloxy)phenyl]methyl acrylate copolymers is much more facile than the same process for similar copolymers containing either [4-(isobutoxycarbonyloxy)phenyl]methyl acrylate or methyl acrylate, a simple alkyl acrylate, as comonomer. During copolymer degradation, [4-(t-butoxycarbonyloxy) phenylmethyl acrylate units are apparently converted to acrylic acid units by extensive fragmentation of the sidechain. Thus, the phenyl t-butyl carbonate moiety does function as a labile acid-sensitive pendant group but its decomposition in this instance leads to the generation of a phenoxybenzyl carboxylate capable of further fragmentation.     

Photochemical grafting of polysulfobetaine onto polyethylene and polystyrene surfaces and investigation of long‐term stability of the polysulfobetaine layer in seawater

Low‐density polyethylene (LDPE) and polystyrene (PS) films with hydrophilic surface were prepared by photochemical grafting of sulfobetaine‐based copolymer containing photolabile moiety, and long‐term stability of the hydrophilic nature of the surfaces in seawater was proved. The sulfobetaine‐based copolymer was prepared by copolymerization of N,N‐dimethyl‐N‐(3‐(methacryloylamino)propyl)‐N‐(3‐sulfopropyl) ammonium betaine with 2 or 5 mol% of N‐methacryloyl‐4‐azidoaniline, and the resulted polymers were grafted onto the plasma pretreated LDPE and PS films. The contact angle measurements were used to prove the modification as well as to follow the changes in the hydrophilicity during storage at room temperature under air atmosphere as well as in seawater at 32°C. The stability of the polymer layer was confirmed also by FTIR and AFM. Polysulfobetaine‐modified LDPE and PS surfaces exhibited significantly higher long‐term hydrophilicity compared with only plasma treated LDPE and PS surfaces.     

Low-Fouling Fluoropolymers for Bioconjugation and In Vivo Tracking

The conjugation of hydrophilic low-fouling polymers to therapeutic molecules and particles is an effective approach to improving their aqueous stability, solubility, and pharmacokinetics. Recent concerns over the immunogenicity of poly(ethylene glycol) has highlighted the importance of identifying alternative low fouling polymers. Now, a new class of synthetic water-soluble homo-fluoropolymers are reported with a sulfoxide side-chain structure. The incorporation of fluorine enables direct imaging of the homopolymer by ¹⁹F MRI, negating the need for additional synthetic steps to attach an imaging moiety. These self-reporting fluoropolymers show outstanding imaging sensitivity and remarkable hydrophilicity, and as such are a new class of low-fouling polymer for bioconjugation and in vivo tracking.     

Synthesis and characterization of novel polybenzimidazoles containing 4-phenyl phthalazinone moiety

A novel series of homo- and copoly(phthalazinone benzimidazole)s were synthesized from various stoichiometric mixtures of 4-(4-(4-(4-carboxyphenoxy)phenyl)-1-oxophthalazin-2(1H)-yl)benzoic acid (CPPBC) and isophthalic acid (IPA) with 3,3′-diaminobenzidine (DAB) by solution polycondensation in polyphosphoric acid (PPA). The structures of the obtained polymers were characterized by FT-IR and ¹H NMR. The obtained polybenzimidazoles were found to be soluble in aprotic polar solvents such as N-methyl-2-pyrolidinone (NMP), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO) and m-cresol, without the addition of inorganic salts. The inherent viscosities of the polybenzimidazoles were in the range of 1.10–2.05 dL/g. All of the polymers show amorphous nature as evaluated by WAXD. These polymers have high glass transition temperatures (T_gs) in the range of 398–408 °C. Thermogravimetric analysis exhibit that these polybenzimidazoles containing 4-phenyl phthalazinone moiety have excellent thermal stability with the temperatures for 5% and 10% weight loss of the polymers ranging from 516 to 594 °C and 560 to 672 °C, respectively.     

Synthesis of starlike PtBA‐g‐PEO amphiphilic graft copolymer via highly efficient Cu‐catalyzed SET‐NRC reaction at ambient temperature

Two new amphiphilic star graft copolymers bearing hydrophobic poly(tert‐butyl acrylate) backbone and hydrophilic poly(ethylene oxide) (PEO) side chains with different molecular weights were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization and single electron transfer‐nitroxide radical coupling (SET‐NRC) reaction under mild conditions. RAFT homopolymerization of tert‐butyl 2‐((2‐bromopropanoyloxy)methyl)acrylate was mediated by a four‐armed chain transfer agent in a controlled way to afford a well‐defined starlike backbone with a narrow molecular weight distribution (M_w/M_n = 1.26). The target poly(tert‐butyl acrylate)‐g‐PEO (PtBA‐g‐PEO) star graft copolymers were synthesized by SET‐NRC reaction between Br‐containing PtBA‐based starlike backbone and PEO end functionalized with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) group using copper/N,N,N′,N′,N″‐pentamethyldiethylenetriamine as catalytic system at ambient temperature via grafting‐onto strategy. The critical micelle concentration values of the obtained amphiphilic star graft copolymers in aqueous media and brine were determined by fluorescence probe technique using pyrene as probe. Diverse micellar morphologies were formed by varying the content of hydrophilic PEO segment as well as the initial concentration of stock solution. In addition, poly(acrylic acid)‐g‐PEO double hydrophilic star graft copolymers were obtained by selective acidic hydrolysis of hydrophobic PtBA starlike backbone without affecting PEO side chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Thermosensitive and redox-active polymers: Preparation and properties of poly(N-ethylacrylamide-co-vinylferrocene) and poly(N,N-diethylacrylamide-co-vinylferrocene)

Thermosensitive and redox-active polymers were prepared by copolymerization of N-ethyl- or N,N-diethylacrylamides with vinylferrocene (VFc). LCST (lower critical solution temperature) of the aqueous copolymer solution was decreased by increasing the ferrocene content in the copolymer. The oxidation of ferrocene led to a significant increase in LCST due to the transition from hydrophobic to hydrophilic character of the ferrocene moiety in the copolymer. The ferrocene content in the copolymer increases with increasing differences between the LCST's of the oxidation and reduction states. The transition could be made reversible by redox reaction using L -ascorbic acid as an oxidant and cerium sulfate as a reductant. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1967–1972, 1997     

Water‐soluble acrylamide copolymers. IX. Preparation and characterization of the cationic derivatives of poly(acrylamide‐co‐n,n‐dimethylacrylamide), poly(acrylamide‐co‐methacrylamide), and poly(acrylamide‐co‐n‐t‐butylacrylamide)

This article extends the preparative details of a series of nonionic copolymers of acrylamide with N,N‐dimethylacrylamide, methacrylamide, and N‐t‐butylacrylamide to the synthesis of cationic derivatives of these new copolymers. The described procedures gave products with cationicities of 14–26 mol %. We measured the mean squared radii of gyration and intrinsic viscosities of aqueous solutions of these products at several different pHs and NaCl concentrations to compare these values with those determined for the nonionic precursors and related commercial cationic polymers. Because the molecular weights of the examples measured varied widely, it was difficult to establish definite trends. However, the large values obtained for the mean squared radii of gyration and intrinsic viscosities, relative to the nonionic precursors of these polymers, demonstrated that the charged groups had a qualitatively greater effect on polymer extension than the nonpolar bulky groups. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2525–2535, 2001     

Low‐Fouling Fluoropolymers for Bioconjugation and In Vivo Tracking

The conjugation of hydrophilic low‐fouling polymers to therapeutic molecules and particles is an effective approach to improving their aqueous stability, solubility, and pharmacokinetics. Recent concerns over the immunogenicity of poly(ethylene glycol) has highlighted the importance of identifying alternative low fouling polymers. Now, a new class of synthetic water‐soluble homo‐fluoropolymers are reported with a sulfoxide side‐chain structure. The incorporation of fluorine enables direct imaging of the homopolymer by ¹⁹F MRI, negating the need for additional synthetic steps to attach an imaging moiety. These self‐reporting fluoropolymers show outstanding imaging sensitivity and remarkable hydrophilicity, and as such are a new class of low‐fouling polymer for bioconjugation and in vivo tracking.     

Fast and effective copper(0)‐mediated simultaneous chain‐ and step‐growth radical polymerization at ambient temperature

Vinyl‐conjugated monomer (methyl acrylate, MA) and allyl 2‐bromopropanoate (ABP)‐possessing unconjugated C?C and active C? Br bonds were polymerized via the Cu(0)‐mediated simultaneous chain‐ and step‐growth radical polymerization at ambient temperature using Cu(0) as catalyst, N,N,N′,N″,N″‐pentamethyldiethylenetriamine as ligand and dimethyl sulfoxide as solvent. The conversion was reached higher than 98% within 20 h. The obtained polymers showed block structure consisting of polyester and vinyl polymer moieties. The Cu(0)‐catalyzed simultaneous chain‐ and step‐growth radical polymerization mechanism was demonstrated by NMR, matrix‐assisted laser desorption ionization time‐of‐flight, and GPC analyses. Furthermore, the obtained copolymers of MA and ABP were further modified with poly(N‐isopropylamide) through radical thiol‐ene “click” chemistry from the terminal double bond. The thermoresponsive behavior of this block copolymer was investigated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3907–3916