Synthesis of new polyfunctional 2-pyrrolidinones from methyl 2-(carboethoxyhydroxymethyl)acrylate

The synthesis of new polyfunctional 2-pyrrolidinone derivatives from methyl 2-(carboethoxyhydroxymethyl)acrylate is described. These alkenes present an extremely high reactivity upon Michael addition with primary amines leading to a simple, mild, and efficient route to the preparation of new polyfunctional pyrrolidinones.     

End group transformations of RAFT‐generated polymers with bismaleimides: Functional telechelics and modular block copolymers

End group activation of polymers prepared by reversible addition‐fragmentation chain transfer (RAFT) polymerization was accomplished by conversion of thiocarbonylthio end groups to thiols and subsequent reaction with excess of a bismaleimide. Poly(N‐isopropylacrylamide) (PNIPAM) was prepared by RAFT, and subsequent aminolysis led to sulfhydryl‐terminated polymers that reacted with an excess of 1,8‐bismaleimidodiethyleneglycol to yield maleimido‐terminated macromolecules. The maleimido end groups allowed near‐quantitative coupling with model low molecular weight thiols or dienes by Michael addition or Diels‐Alder reactions, respectively. Reaction of maleimide‐activated PNIPAM with another thiol‐terminated polymer proved an efficient means of preparing block copolymers by a modular coupling approach. Successful end group functionalization of the well‐defined polymers was confirmed by combination of UV–vis, FTIR, and NMR spectroscopy and gel permeation chromatography. The general strategy proved to be versatile for the preparation of functional telechelics and modular block copolymers from RAFT‐generated (co)polymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5093–5100, 2008     

Synthesis and micellization of star‐like hyperbranched polymer with poly(ethylene oxide) and poly(ε‐caprolactone) arms

Novel star‐like hyperbranched polymers with amphiphilic arms were synthesized via three steps. Hyperbranched poly(amido amine)s containing secondary amine and hydroxyl groups were successfully synthesized via Michael addition polymerization of triacrylamide (TT) and 3‐amino‐1,2‐propanediol (APD) with feed molar ratio of 1:2. ¹H, ¹³C, and HSQC NMR techniques were used to clarify polymerization mechanism and the structures of the resultant hyperbranched polymers. Methoxyl poly(ethylene oxide) acrylate (A‐MPEO) and carboxylic acid‐terminated poly(ε‐caprolactone) (PCL) were sequentially reacted with secondary amine and hydroxyl group, and the core–shell structures with poly(1TT‐2APD) as core and two distinguishing polymer chains, PEO and PCL, as shell were constructed. The star‐like hyperbranched polymers have different sizes in dimethyl sulfonate, chloroform, and deionized water, which were characterized by DLS and ¹H NMR. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1388–1401, 2008     

One‐pot synthesis of linear and branched poly(amide aspartimide)s with good solubility in organic solvents

Linear and branched poly(amide aspartimide)s were prepared through the reaction of 4,4′‐diaminodiphenylmethane with 4‐maleimidobenzoic acid and 5‐maleimidoisophthalic acid, respectively. The synthesis was performed through a one‐pot operation by means of the Michael addition reaction between amine and maleimide groups and the dehydration condensation reaction between amine and carboxylic acid groups. The obtained polymers exhibited fairly good solubility in aprotic polar solvents at room temperature and in pyridine, tetrahydrofuran, acetone, and chloroform upon heating. High glass‐transition temperatures (≥225 °C) and thermal stability above 360 °C were found for the polymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1923–1929, 2005     

Polymer functionalization by free radical addition to alkynes

A new chemical modification of saturated polymers involving free radical addition to mono‐substituted alkynes is presented and examined in terms of reaction yield, graft structure, and changes to molecular weight. Solvent‐free, peroxide‐initiated reactions of ethyl propiolate and poly(ethylene oxide) provide good yields of ethyl (2‐E,Z)‐3‐alkylacrylates, whereas less efficient hydrogen atom donation by polyethylene impacts negatively on reaction yields and encourages alkyne oligomerization. Model compounds are used to characterize alkyne grafting products, and to probe the relationship between reagent properties, reaction yields, and product structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7386–7394, 2008     

One‐pot synthesis of soluble and fluorescent aliphatic hyperbranched poly(amide‐imide) with solvent‐dependent emission

Aliphatic hyperbranched poly(amide‐imide) was facilely prepared by employing a functional thiolactone‐maleimide monomer. Highly efficient, selective and quantitative properties of amine‐maleimide Michael addition and aminolysis of a thiolactone guaranteed the generation of an ABB' thiol‐yne intermediate without side products, followed by consecutive thiol‐yne click reaction in one‐pot. The hyperbranched structure of the poly(amide‐imide) was confirmed by NMR spectroscopy and triple‐detector GPC/SEC analysis. Additionally, due to the presence of aminosuccinimide fluorophores and intrinsic physical property of hyperbranched polymers, this aliphatic hyperbranched poly(amide‐imide) possessed solvent‐dependent emission and presented good solubility in various organic solvents. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2053–2060     

Michael addition polymerizations of difunctional amines (AA′) and triacrylamides (B3)

Novel hyperbranched poly(amido amine)s containing tertiary amines on the backbones and acryl or secondary amines as the surface groups were successfully synthesized via the Michael addition polymerizations of a triacrylamide [1,3,5‐triacryloylhexahydro‐1,3,5‐triazine (TT)] and a difunctional amine [n‐butylamine (BA)] NMR techniques were used to clarify the structures of hyperbranched polymers and polymerization mechanism. The reactivity of the secondary amine formed in situ was much lower than that of the primary amines in BA. When the feed molar ratio was 1:1 TT/BA, the secondary amine formed in situ was almost kept out of the reaction before the BA (AA′) and TT (B₃) monomers were consumed, and this led to the formation of A′B₂ intermediates containing one secondary amine group and two acryl groups. The self‐polymerization of the A′B₂ intermediates produced hyperbranched polymers bearing acryl as surface groups. For the polymerization with the feed molar ratio of 1:2 TT/BA, A′₂B intermediates containing one acryl group and two secondary amine groups were accumulated until self‐polymerization started; the self‐polymerization of the intermediates formed hyperbranched polymers with secondary amines as their surface groups. Modifications of surface functional groups were studied to form new hyperbranched polymers. The hyperbranched poly(amido amine)s were amorphous. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6226–6242, 2006     

Preparation and characterization of novel hyperbranched poly(amido amine)s from Michael addition polymerizations of trifunctional amines with diacrylamides

Novel hyperbranched poly(amido amine)s containing tertiary amines in the backbones and acryl as terminal groups were synthesized via the Michael addition polymerizations of trifunctional amines with twofold molar diacrylamide. The hyperbranched structures of these poly(amido amine)s were verified by ¹³C NMR (INVGATE). The polymerization mechanisms were clarified by following the polymerization process with NMR method, and the results show that the reactivity of secondary amine formed in situ is much lower than that of the secondary amine in 1‐(2‐aminoethyl) piperazine (AEPZ) ring and the primary amine. The secondary amine formed in situ was almost kept out of the reaction before the primary and secondary amines in AEPZ were consumed, leading to the formation of the AB2 intermediate, and the further reaction of the AB2 yielded the hyperbranched polymers. The molecular weights and properties of poly(amindo amine)s obtained were characterized by GPC, DSC, and TGA, respectively. Based on the reaction of active acryl groups in the polymers obtained with glucosamine, hyperbranched polymers containing sugar were formed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5127–5137, 2005     

Functionalized poly(phenylene‐alt‐bithiophenes): Synthesis,chiroptical properties,and interaction with chiral amines

New functionalized, (a)chiral poly(phenylene‐alt‐bithiophene)s were prepared and their chiroptical properties were studied. The polymers were prepared by a Stille coupling reaction and were functionalized with protected carboxylic acid and amino functions (tert‐butyl ester and BOC respectively). The polymers are present as well conjugated rigid rods in solution, which (chirally) aggregate in nonsolvents and film. In a next step, the protecting group (tert‐butyl ester in case of the carboxylic acid) was removed. Aggregation of this polymer can be induced by addition of amines; if chiral amines are used, the polymer chains chirally stack. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4817–4829, 2008     

Water soluble poly(ethylene oxide) functionalized norbornene polymers

The synthesis of three different poly(ethylene oxide) macromonomers with a norbornene and oxanorbornene end group is presented. The macromonomers were polymerized to comb‐polymers by ring‐opening metathesis polymerization (ROMP) using Grubbs' Catalyst G3 to produce water soluble polymers with polydispersities between 1.04 and 1.30 and molecular weights between 14,000 and 50,000 g/mol. Characterization by static and dynamic light scattering reveals that the comb‐polymers with norbornene backbone are molecularly disperse in aqueous solution, while the oxanorbornene‐backbone polymers form small water‐soluble aggregates. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2640–2648, 2008     

Tunable poly(hydroxyl urethane) from CO2‐Based intermediates using thiol‐ene chemistry

CO₂‐based, crosslinked poly(hydroxyl urethane)s (PHUs) are accessed via a set of efficient reactions based on the addition chemistry of thiol‐ene and amines‐cyclic carbonates. This strategy to utilize 5‐membered cyclic carbonates produced from CO₂ is robust, facile, modular, and atomically efficient in nature. The thiol‐ene reaction was utilized to access bis(cyclic carbonate), tris(cyclic carbonate), and tetrakis(cyclic carbonate) in quantitative yield from 4‐vinyl‐1,3‐dioxolan‐2‐one and thiols. Multi‐functional cyclic carbonates were simply mixed with diethylenetriamine and/or 1,6‐diaminohexane to generate crosslinked PHUs from 25 to 80 °C. These materials are easy to scale‐up and are potential candidates in many applications such as coatings, binders, and resins. The resulting polymers have glass transition temperatures between ?1 and 16 °C and thermal decomposition temperatures from 190 to 230 °C. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Preparation of 3‐arm star polymers (A3) via Diels–Alder click reaction

Diels–Alder click reaction was successfully applied for the preparation of 3‐arm star polymers (A₃) using furan protected maleimide end‐functionalized polymers and trianthracene functional linking agent (2) at reflux temperature of toluene for 48 h. Well‐defined furan protected maleimide end‐functionalized polymers, poly (ethylene glycol), poly(methyl methacrylate), and poly(tert‐butyl acrylate) were obtained by esterification or atom transfer radical polymerization. Obtained star polymers were characterized via NMR and GPC (refractive index and triple detector detection). Splitting of GPC traces of the resulting polymer mixture notably displayed that Diels–Alder click reaction was a versatile and a reliable route for the preparation of A₃ star polymer. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 302–313, 2008     

Living star polymer formation (RAFT) studied via electrospray ionization mass spectrometry

A mass spectrometry analysis has been performed on complex architecture polymeric material produced during reversible addition fragmentation chain transfer (RAFT) polymerizations yielding star polymers. Para‐acetoxystyrene (AcOSty) has been polymerized at 60 °C, using azobisisobutyronitrile (AIBN) as the thermally decomposing initiator, in the presence of the R‐group approach tetrafunctional RAFT agent (1,2,4,5‐tetrakis‐(2‐phenyl‐thioacetyl‐sulfanylmethyl)‐benzene). In addition to ideal star material, a variety of products unique to this mode of polymerization have been identified. These include star–star couples, stars terminated with initiator fragments, star–star couples terminated with initiator fragments and linear polymers, supporting the notion that these species are responsible for the structured molecular‐weight distributions measured for these systems when analyzed via gel permeation chromatography. The analysis begins with a study of AcOSty polymerizing (i) in the absence of any mediating agent and (ii) in the presence of a monofunctional RAFT agent, revealing the mode of termination of propagating poly(AcOSty) radicals as combination and that some ionization biases exist among variants of poly (AcOSty). The interpretation of the mass spectrometry data has been aided by a novel kinetic model of star polymerizations, allowing the rationalization of experimental observations with theoretical expectations. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1873–1892, 2008     

Influence of alkyl chains of amphiphilic hyperbranched poly(ester amine)s on the phase‐transfer performances for acid dye and the aggregation behaviors at the interface

Hyperbranched poly(ester amine) (HPEA) with terminal secondary amine groups was synthesized by the Michael addition reaction between piperazine and trimethylolpropanetriacrylate with a molar ratio of 13:6. It was further reacted with a series of aliphatic acid chlorides, including stearoyl chloride, dodecanoyl chloride, and octanoyl chloride, to yield three modified amphiphilic hyperbranched polymers, which were termed HPEA‐C18, HPEA‐C12, and HPEA‐C8, respectively. These polymers were characterized with Fourier transform infrared, ¹H NMR, gel permeation chromatography, and differential scanning calorimetry measurements. Because of the existence of interior tertiary amine groups, the modified amphiphilic polymers were used as host molecules to extract the guest acid dye, methyl orange (MO), from the aqueous layer to the organic layer on the basis of the acid–base interaction. The influences of the pH of the aqueous layer and the length of the alkyl chains in the modified polymers on the phase‐transfer performances were investigated. The results indicated that more MO molecules could be extracted at a lower pH because of the formation of more quaternary ammonium ions within the host molecules. As the length of the alkyl chains in the modified polymers increased, both the transfer capability and the intermolecular aggregation at the interface were enhanced. The extracted MO could be reversibly released from the organic layer to the aqueous layer under basic conditions. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2921–2930, 2005     

Poly(4‐acryloylmorpholine) oligomers carrying a β‐cyclodextrin residue at one terminus

A straightforward synthesis of amphiphilic β‐cyclodextrin‐poly(4‐acryloylmorpholine) (β‐CD‐PACM) polymers of controlled molecular weight, consisting of the radical polymerization of 4‐acryloylmorpholine in the presence of 6‐deoxy‐6‐mercapto‐β‐cyclodextrin (β‐CD‐SH) as chain‐transfer agent, has been established. These derivatives carry a single β‐cyclodextrin (β‐CD) moiety at one terminus and their average molecular weight is in the order of 10⁴. Thus, their β‐CD content is ～ 10% by weight. No evidence of un‐functionalized PACM was found in the final products. The chain‐transfer constant (C_T) of β‐CD‐SH was found to be 1.30 by independently determining the reaction constants of both chain‐transfer and propagation reactions. This ensures that the molecular weight, hence the β‐CD content of the polymers, does not significantly vary with conversion. These β‐CD‐PACM polymers are highly soluble in water as well as in several organic solvents such as chloroform and lower alcohols. They proved capable of solubilizing in water poorly soluble drugs such as 9‐[(2‐hydroxyethoxy)methyl]guanine (Acyclovir) and of gradually releasing them in aqueous systems. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1607–1617, 2008     

Poly(caprolactone) containing highly branched segmented poly(ester urethane)s via A2 with oligomeric B3 polymerization

Highly branched, poly(caprolactone) (PCL) containing segmented poly(ester urethane)s were synthesized via polymerization of A₂ and oligomeric B₃ type monomers. An isocyanate functional butanediol‐based A₂ hard segment was synthesized and immediately reacted with a poly(caprolactone)‐based trifunctional (B₃) soft segment. Characterization of thermal properties using DMA and DSC analysis demonstrated that the PCL segment remained amorphous in branched poly(ester urethane)s. Conversely, the crystallinity of PCL segment was retained to some extent in a linear analogue with equivalent soft segment molecular weight. Tensile testing revealed a slight decrease in Young's modulus and tensile strength for the highly branched polymers compared with a linear analogue. However, highly branched poly(ester urethane)s demonstrated lower hysteresis. In addition to synthesis of highly branched polymers, poly(ester urethane) networks were synthesized from a highly branched hydroxyl‐terminated precursor and a low molar mass diisocyanate as the crosslinking agent. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6285–6295, 2008     

Study on the preparation and the self‐assembly of poly(propyleneimine)–poly(styrene) nanoparticles

Using 2‐chloropropionamide derivative of poly(propyleneimine) dendrimer DAB‐dendr‐(NH₂)₃₂ (DAB‐32‐Cl) as the macroinitiator, atom transfer radical polymerization of styrene was successfully carried out in DMF medium. The monodisperse poly(propyleneimine)–polystyrene (dendrimer–PSt) particles with diameters smaller than 100 nm could be prepared. The morphology, size, and size distribution of the dendrimer–PSt particles were characterized by transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS). The effects of reaction temperature, the ratio of St/macroinitiator, and reaction time on the size, and size distribution of the dendrimer–PSt nanoparticles were investigated. In a selective solvent (DMF/H₂O), polymers can self‐assemble into different aggregate configurations such as regular microsphere and wire‐like thread. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2658–2666, 2008     

Persistent and emission color tunable poly(phenylene‐ethynylene)s covered with polyhedral oligomeric silsesquioxanes

The development of chemically and thermally persistent blue‐, and green‐luminescent hybrid π‐conjugated polymers consisting of poly(phenylene‐ethynylene) conjugated backbone wrapped with the rigid three‐dimensional polyhedral oligomeric silsesquioxane (POSS) units was successfully achieved by means of the Sonogashira‐Hagihara coupling reaction. Because of the steric effect of POSS units, the luminescence stability of the conjugated backbone was significantly enhanced. Moreover, emission color was also easily tunable only by changing the ratio of POSS moieties incorporated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8112–8116, 2008     

Synthesis of multiblock hyperbranched‐linear poly(ether sulfone) copolymers

Hyperbranched poly(ether sulfone) was prepared in the presence of an oligomeric linear poly(ether sulfone) to generate multiblock hyperbranched‐linear (LxHB) copolymers. The LxHB copolymers were prepared in a two‐step, one‐pot synthesis by first polymerizing AB monomer to generate a linear block of a desired molecular weight followed by addition of the AB₂ monomer in a large excess (19:1, AB₂:AB) to generate the hyperbranched block. NMR integration analysis indicates that AB₂:AB ratio is independent of the reaction time. Because the molecular weight still increases with reaction time, these results suggest that polymer growth continues after consumption of monomer by condensation into a multiblock architecture. The LxHB poly(ether sulfone)s have better thermal stability (10% mass loss > 343 vs. 317 °C) and lower T_g (200 vs. > 250 °C) than the hyperbranched homopolymer, higher T_g than the linear homopolymer (<154 °C), while little difference in the solubility character was observed between the two polymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4785–4793, 2008     

Aza‐Michael addition reaction: Post‐polymerization modification and preparation of PEI/PEG‐based polyester hydrogels from enzymatically synthesized reactive polymers

The utility of aza‐Michael addition chemistry for post‐polymerization functionalization of enzymatically prepared polyesters is established. For this, itaconate ester and oligoethylene glycol are selected as monomers. A Candida Antarctica lipase B catalyzed polycondensation reaction between the two monomers provides the polyesters, which carry an activated carbon‐carbon double bond in the polymer backbone. These electron deficient alkenes represent suitable aza‐Michael acceptors and can be engaged in a nucleophilic addition reaction with small molecular mono‐amines (aza‐Michael donors) to yield functionalized linear polyesters. Employing a poly‐amine as the aza‐Michael donor, on the other hand, results in the formation of hydrophilic polymer networks. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 745–749