Polysilylether: A Degradable Polymer from Biorenewable Feedstocks

The synthesis of polysilylethers (PSEs) using a monomer derived from a biorenewable feedstock is reported. The AB‐type monomer was synthesized from undecenoic acid through hydrosilylation and reduction, and the polymerization was catalyzed by earth‐abundant metal salts. High‐molar‐mass products were achieved, and the degree of polymerization was controlled by varying the amount of an AA‐type monomer in the reaction. The PSEs possess good thermal stability and a low glass‐transition temperature (T_g≈?67 °C). To demonstrate the utility of the PSEs, polyurethanes were synthesized from low‐molar‐mass hydroxy‐telechelic PSEs.     

Synthesis and properties of polymeric analogs of ionic liquids

A number of methacrylate ionic monomers with different structures and mobilities of ionic centers were synthesized. The free-radical polymerization of these monomers in solution affords high-molecular-mass (M _sD = 0.5 to 2.5 × 10⁶) thermally stable (T _dec > 170°C) polyelectrolytes or cationic or anionic “polymeric ionic liquids.” The conductivities of polycation- and polyanion-derived coatings are (7.4 × 10^?10)?(7.6 × 10^?7) and (4.9 × 10^?10)-(1.6 × 10^?7) S/cm (25°C), respectively. As exemplified by poly(1-[3-(methacryloyloxy)propyl]-3-methylimidazolium bis[(trifluoromethanesulfonyl)imide]), the molecular mass and glasstransition temperature of the polymer affect the ionic conductivity of the film coating. The transition from linear polyelectrolytes to crosslinked systems based on ionic monomers and poly(ethylene glycol dimethacrylate) 750 leads to the formation of elastic films featuring satisfactory strength, reduced glass-transition temperatures (?8 to +15°C), and increased ionic conductivity (up to 3.2 × 10^?6 S/cm (25°C)).     

Synthesis and properties of renewable nonisocyanate polyurethanes (NIPUs) from dimethylcarbonate

Novel fully renewable AA‐BB type nonisocyanate polyurethanes (NIPUs) were synthesized using the transurethanization approach. Dicarbamate monomers were prepared by the reaction of a diamine with an excess of dimethylcarbonate (DMC), in presence of 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) as catalyst. Then, the dicarbamate was reacted with a diol to afford the polymer, in presence of TBD or K₂CO₃ as catalyst. Several renewable diamines and diols were tested. The two steps were conducted under neat conditions. The obtained materials exhibited T_g values varying from ?38 to 42 ° C, T_m values varying from 42 to 204 °C , and thermal stabilities above 200 ° C. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1351–1359     

Synthesis and polymerization reactions of cyclic imino ethers. 5: naphthalene unit‐containing poly(ether amide)s

Poly(ether amide)s containing naphthalene unit were prepared either by the polyaddition reaction of aromatic bis(2‐oxazoline)s with the different dihydroxynaphthalenes or by the homopolyaddition of a monomer containing an oxazoline, a hydroxy, and naphthalene moieties. First, polymerization method represents AA + BB mode where 1,4‐phenylene‐2,2′‐bis(2‐oxazoline) (A) and 1,3‐phenylene‐2,2′‐bis(2‐oxazoline) (B) were used as AA monomers and four different dihydroxynaphthalenes 1–4 were used as BB monomers. In the second case, 2‐(6‐hydroxynaphthalene‐2‐yl)‐2‐oxazoline (5) was used as AB‐type monomer in thermally induced polymerizations. The time dependences of polyadditions in bulk as well as in the solution were examined. The reduction of molar mass was observed after the initial fast increase of molar mass. This can be explained by the presence of side and degradation reactions. In both cases, polyadditions resulted in the linear poly(ether amide)s, which were characterized by ¹H and ¹³C NMR spectroscopy. Thermal properties of the prepared polymers were studied by differential scanning calorimetry (DSC) measurements. Comparison of the temperatures of glass transition for polymers prepared in AA + BB mode shows the strong dependence of thermal properties on the structure of the polymers. The values were in the range of 136–171°C. The glass‐transition temperature (T_g) of poly[2‐(6‐hydroxynaphthalene‐2‐yl)‐2‐oxazoline] prepared by AB‐type polyaddition is 183°C, which corresponds to the higher contents of hard aromatic segments in the latter type of polymers compared to the polymers prepared in the AA + BB‐type polyadditions. The described polymers represent novel naphthalene unit‐containing poly(ether amide)s for different applications in material science. Copyright © 2011 John Wiley & Sons, Ltd.     

Water uptake and dye sorption studies of chemically crosslinked highly swollen novel ternary acrylamide‐based hydrogels including citraconic acid and sodium acrylate

Highly swollen hydrogels made by the polymerization of acrylamide (AAm) with some anionic monomers such as citraconic acid (CITA) and sodium acrylate (SA) were investigated as a function of composition to find materials with swelling and dye sorption properties. Highly swollen AAm/CITA/SA or AAm/SA/CITA hydrogels were prepared by free radical solution polymerization in aqueous solutions of AAm with CITA and SA as co‐monomers and two multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4‐butanediol dimethacrylate (BDMA). Swelling experiments were performed in water at 25°C, gravimetrically. Chemically crosslinked AAm/CITA/SA or AAm/SA/CITA hydrogels were used in experiments on sorption of water‐soluble monovalent cationic dye such as “Nil blue” (Basic Blue 12; BB 12). Equilibrium percentage swelling values of AAm/CITA/SA or AAm/SA/CITA hydrogels were calculated in the range of 1797–22,098%. Some swelling kinetic parameters were found. Diffusion behavior of water was investigated. Water diffusion into the hydrogels was found to be non‐Fickian in character. For sorption of cationic dye, BB 12 into the hydrogels was studied by batch sorption technique at 25°C. AAm/CITA/SA or AAm/SA/CITA hydrogels in the dye solutions showed coloration, whereas AAm hydrogel did not show sorption of any dye from the solution. The sorption capacity of AAm/CITA/SA or AAm/SA/CITA hydrogels was investigated. At the end of the experiments, 21.70–78.91% BB 12 adsorptions were determined. Copyright © 2007 John Wiley & Sons, Ltd.     

Hydrophobically modified polyelectrolytes III. Reactivity ratio determination of FX14/AA,LA/AA and SA/AA

The reactivity ratios of three hydrophobic monomers, FX14, LA and SA, to hydrophilic monomer, acrylic acid (AA), were determined. For the fluorocarbon containing hydrophobic monomer FX14, elemental analysis was adopted to obtain the relative content of FX14 to AA. For two hydrocarbon monomers, ¹³C NMR was used. FR, KT linear method and EVM nonlinear method were applied in calculating reactivity ratios. It is found that the reactivity of LA and SA is lower than that of AA, for solution polymerization in cyclohexane. Whereas FX14 is more reactive than AA in benzene. Finally, the distribution of small amounts of these hydrophobic monomers along the polymeric chain is discussed and a random sequence is confirmed     

Synthesis of bio-based poly(methacrylates) using SG1-containing amphiphilic macroinitiators by nitroxide mediated miniemulsion polymerization

SG1-based amphiphilic macroinitiators were synthesized from oligoethylene glycol methyl ether methacrylate and 10 mol% acrylonitrile or styrene (as the controlling comonomer) to conduct the nitroxide mediated polymerization of bio-based methacrylic monomers (isobornyl methacrylate (IBOMA) and C13 alkyl methacrylate (C13MA)) in miniemulsion. The effect of the addition of surfactant (DOWFAX 8390), co-stabilizer (n-hexadecane) and different reaction temperatures (80, 90 and 100°C) on polymerization kinetics was studied. We found that the NMP of IBOMA/C13MA using amphiphilic macroalkoxyamines were most effective during miniemulsion polymerization (linear trend of M_n versus conversion and high latex stability) in presence of 2 wt% surfactant and 0.8 wt% co-stabilizer (relative to monomer) at 90°C. The effect of surfactant, co-stabilizer and temperature on particle size during the polymerization was studied and suggested a decrease in initial particle size with the addition of surfactant and co-stabilizer. Finally, the thermal properties of IBOMA/C13MA polymers, prepared by amphiphilic macroinitiators, were examined thoroughly, indicating a T_g in the range of −44°C < T_g < 109°C.     

Organocatalytic synthesis of novel renewable non‐isocyanate polyhydroxyurethanes

Novel fully renewable AA‐BB type non‐isocyanate polyhydroxyurethanes were synthesized by the classical reaction between a diamine and a dicyclocarbonate. Sebacic acid was first reacted with an excess of glycerol carbonate, in presence of DCC and DMPA, leading to a renewable dicyclocarbonate monomer. Then, this monomer was reacted with several renewable diamines, in presence of 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD), as organocatalyst, to afford linear and branched polymers. The obtained materials exhibited T_g values varied from ?27 to ?8 °C, T_m values varying from 100 to 165 °C, and thermal stabilities above 200 °C. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 758–764     

Acyclic diene metathesis polymerization of tailor-made monomers towards sequence-regulated vinyl copolymers

 Acyclic diene metathesis polymerization (ADMET) enables convenient transfer of sequential information of the designed monomers to the corresponding sequence-regulated copolymers. In this study, two structurally symmetric monomers, M1 and M2, were synthesized via atom transfer radical addition (ATRA) of diethyl meso-2,5-dibromohexanedioate with 1,5-hexadiene and 1,7-octadiene, respectively. Thus, sequenced segment of VB-EA-EA-VB (VB and EA represent vinyl bromide and ethyl acrylate, respectively) was incorporated into the ADMET diene monomers. ADMET polymerization of these two monomers with Grubbs first generation catalyst (Grubbs-I) was performed in CH₂Cl₂ at 40℃ for 5 days under nitrogen purge. Effects of catalyst amount, monomer concentration and methanol precipitation on the M_p and PDI of polymers were investigated by GPC, and the structures of the formed polymers were characterized by NMR. Our results indicate that using 3.0 mol% of Grubbs-I to monomer can afford polymers with high M_p. Moreover, selective precipitation in methanol enables complete removal of low molecular weight components from the crude products. Meanwhile, M2 exhibits higher ADMET polymerization reactivity than M1 due to its capability of suppressing negative neighboring group effect.     

Synthesis and Characterization of Organosoluble Polyimides Containing Pyridyl Moiety with Ether Linkages

Two novel diamine monomers, bis(4‐amino‐3,5‐dimethylphenyl)‐3‐pyridyl methane and bis(4‐aminophenoxy‐3,5‐dimethylphenyl)‐3‐pyridyl methane were synthesized. A series of pyridine containing aromatic polyimides derived from the diamines were synthesized through a typical two‐step polymerization method. Most of the polymers show good solubility in NMP, DMAc, DMF, DMSO and CHCl₃ at room temperature. These polyimides exhibit T_g in the range of 249–317°C and 10% wt loss (T₁₀) takes place in the range of 474–564°C in N₂ and 469–558°C in air. The polymers have tensile strength in the range of 88–96 MPa, elongation at break in the range of 8.5–12.5% and tensile modulus in the range of 1.5–2.1 GPa. These polyimides also have low dielectric constant (3.26–3.64 at 1 KHz and 3.24–3.61 at 10 KHz) and low moisture absorption (0.42–0.89%).     

Synthesis and properties of hyperbranched polyurethanes,hyperbranched polyurethane copolymers with and without ether and ester groups using blocked isocyanate monomers

Starting from 3,5‐diamino benzoic acid, 2‐hydroxy propyl[3,5‐bis{(benzoxycarbonyl)imino}]benzyl ether, an AB₂‐type blocked isocyanate monomer with flexible ether group, and 2‐hydroxy propyl[3,5‐bis{(benzoxycarbonyl)imino}]benzoate, an AB₂‐type blocked isocyanate monomer with ester group, were synthesized for the first time. Using the same starting compound, 3,5‐bis{(benzoxycarbonyl)imino}benzylalcohol, an AB₂‐type blocked isocyanate monomer, was synthesized through a highly efficient short‐cut route. Step‐growth polymerization of these monomers at individually optimized experimental conditions results in the formation of hyperbranched polyurethanes with and without ether and ester groups. Copolymerizations of these monomers with functionally similar AB monomers were also carried out. The molecular weights of the polymers were determined using GPC and the values (M_w) were found to vary from 1.5 × 10⁴ to 1.2 × 10⁶. While hyperbranched polyurethanes having no ether or ester group were found to be thermally stable up to 217 °C, hyperbranched poly(ether–urethane)s and poly(ester–urethane)s were found to be thermally stable up to 245 and 300 °C, respectively. Glass transition temperature (T_g) of polyurethane was reduced significantly when introducing ether groups into the polymer chain, whereas T_g was not observed even up to 250 °C in the case of poly(ester–urethane). Hyperbranched polyurethanes derived from all the three different AB₂ monomers were soluble in highly polar solvents and the copolymers showed improved solubility. Polyethylene glycol monomethyl ether of molecular weight 550 and decanol were used as end‐capping groups, which were seen to affect the thermal, solution, and solubility properties of polymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3877–3893, 2007     

Monitoring the formation of polystyrene/silica nanocomposites from vinyl triethoxysilane containing copolymers

Random copolymers of polystyrene-co-polyvinyl triethoxysilane (PS-co-PVTES) were prepared via semi-batch emulsion polymerization with different feed monomer compositions and evaluated as precursors of polystyrene (PS)/silica nanocomposites. Small-angle X-ray scattering (SAXS) profiles acquired from 20 °C to 180 °C showed that, at temperatures higher than glass transition temperature (T _g) of PS, the latex particles aggregate. On thermal annealing at 180 °C, silica-rich domains are formed, as corroborated by scanning electron microscopy. Infrared spectroscopy and differential scanning calorimetry analyses showed a reduction of the silanol concentration and an increase in the T _g value, respectively. The silica long domain spacing, measured by SAXS, depends on the concentration of vinyl triethoxysilane (VTES) in the feed; this value varied from 35 to 57 nm when the weight ratio of the monomers (styrene/VTES) was 50:50 and 90:10, respectively.     

Preparation of new poly(ester triazole) and poly(amide triazole) by “click chemistry”

New dialkynyl monomers containing furan and ester or amide units were prepared via three step reactions from ethyl furan-2-carboxylate. Their click polymerization with either poly(ethylene glycol) diazide or poly(tetrahydrofuran) diazide catalyzed by Cu(I) led to corresponding amorphous poly(ester triazole) and poly(amide triazole) with molecular weights in the range of (7–11) × 10³ and with glass transition temperatures in the range of ?35 and ?19°C. The temperature at 5% wt loss (T ₁₀), determined from TGA of polyazomethines were in the range 345–365°C indicating their good thermal stability.     

A quick and green ionic liquid-mediated approach for the synthesis of high-performance, organosoluble and thermally stable polyimides

Three diamine monomers with different derivatives of imidazole heterocyclic ring and meta-linked aryl ethers were synthesized and used in polycodensation reaction with various commercial dianhydrides for preparation of a series of novel poly(ether-imide) (PEI)s. The polycodensation reactions were carried out by using conventional method and in a green medium of ionic liquid (IL) without using NMP-pyridine-acetic anhydride. The PEIs were obtained in good yields (80% 96%) with moderate viscosity (0.48 0.66 dL/g) in a shorter reaction time (10 h) in IL as compared with the conventional method (36 h). All of the polymers were amorphous in nature, showed excellent solubility in amide-type polar aprotic solvents with ability to form tough and flexible films, and excellent thermal stability with Tgs in the range of 212 340 ℃ and 10% weight loss temperature (T10) up to 570℃ in N 2 and 528 ℃ in air.     

Benzocyclobutene in polymer synthesis. I. Homopolymerization of bisbenzocyclobutene aromatic imides to form high-temperature resistant thermosetting resins

A series of new bisbenzocyclobutene-terminated aromatic imide monomers has been synthesized from the condensation reaction of 4-aminobenzocyclobutene and the perspective dianhydride in refluxing acetic acid/toluene. The differential scanning calorimetric studies of the foregoing monomers indicated that polymerization exotherms began at 229–250°C and reached their maxima at 258–263°C. The cured samples (250–254°C; N₂; 8 h) were surprisingly stable toward thermo-oxidative degradation; only 7–10% weight loss was observed after 200 h (in air) at 314°C (600°F). At higher temperatures (650 and 700°F), the most rigid structure was the most thermo-oxidatively stable. An approach to enhance both the final glass-transition temperature (T_g cure) and the thermo-oxidative stability of the bisbenzocyclobutene system was to dilute the cure-site density since the cure-site structure is the weakest part of the polymeric structure. Therefore, a series of bisbenzocyclobutene-terminated aromatic imide oligomers were prepared, using various aromatic amines as the chain-extending agents. Meta-phenylenediamine was apparently the most effective in the advancement of both the T_g (cure) and thermo-oxidative stability.     

Synthesis of Block Copolymers of 2‐Ethylhexyl Methacrylate,n‐Hexyl Methacrylate and Methyl Methacrylate via Anionic Polymerization at Ambient Temperature

It still remains a concern to break through the bottlenecks of anionic polymerization of polar monomers, such as side reactions, low conversion and low temperature (–78°C). In this work, potassium tert‐butoxide (t‐BuOK) was chosen to initiate the anionic polymerization of 2‐ethylhexyl methacrylate (EHMA) in tetrahydrofuran. The conversions were above 99% at 0 or 30°C, and above 95% at 60°C without side reaction inhibitors. The high conversions implied t‐BuOK could suppress the side reactions. A series of block copolymers of EHMA, n‐hexyl methacrylate (HMA) and methyl methacrylate (MMA) were further synthesized at 0°C, and the conversions were all above 99%. The GPC and ¹H NMR results confirmed the successful synthesis of the block copolymers. The molecular size of monomer and the state of t‐BuOK (free ion pairs or aggregates) remarkably affected the polymerization rates and the molecular structures of the products. The DMA results indicated that the glass transition temperatures of PEHMA or PHMA block and PMMA block were 20°C and 60°C, respectively, which deviated from –2°C and 105°C of homopolymer, respectively, due to the partial compatibility of the blocks. This work explored a route of the anionic polymerization of polar monomers at room temperature.     

Novel cyano-containing copolymers of vinyl esters for piezoelectric materials

The synthesis of a series of novel cyano-containing copolymers is described. Alternating copolymers of acrylonitrile with vinyl esters are obtained by increasing the electrophilic character of the nitrile monomers by complexation with zinc chloride. Copolymers of methyl and ethyl α-cyanoacrylates with vinyl esters are prepared using radical initiators in the presence of 7% acetic acid as inhibitor for anionic polymerization. The copolymers of methyl α-cyanoacrylate with the vinyl esters have T_g's above 140°C. Methyl vinylidene cyanide (MVCN) copolymerizes spontaneously with para-substituted styrenes to yield copolymers with high inherent viscosities and high T_g (160°C) and the copolymer of MVCN with vinyl acetate is also synthesized. The pyroelectric constants p for these polymers were measured and the values of p for the copolymers of vinyl acetate with methyl β,β-dicyanoacrylate, methyl α-cyanoacrylate, or MVCN were in the same range as the well-studied vinylidene cyanide/vinyl acetate copolymer. A higher concentration of dipoles generally results in higher T_g's and higher pyroelectric coefficients. © 1992 John Wiley & Sons, Inc.     

Living anionic polymerization of lauryl methacrylate and synthesis of block copolymers with methyl methacrylate

Anionic polymerization of lauryl methacrylate (LMA) with 1,1‐diphenylhexyl lithium in tetrahydrofuran (THF) at ?40 °C resulted in a multimodal and broad molecular weight distribution (MWD) with poor initiator efficiency. In the presence of additives such as dilithium salt of triethylene glycol (G₃Li₂), LiCl, and LiClO₄, the polymerization resulted in polymers with a narrow MWD (≤ 1.10). Diblock copolymers of methyl methacrylate (MMA) and LMA were synthesized by anionic polymerization using DPHLi as initiator in THF at ?40 °C with the sequential addition of monomers. The molecular weight distribution of the polymers was narrow and without homopolymer contamination when LMA was added to living PMMA chain ends. Diblock copolymers with broad/bimodal MWD were obtained with a reverse‐sequence monomer addition. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 875–882, 2004     

Polyimides derived from diels-alder polymerization of furfuryl-substituted maleamic acids or from the reaction of bismaleamic with bisfurfurylpyromellitamic acids

Certain AB or AA and BB Diels-Alder polymer precursors bearing maleimide and furan segments were synthesized, characterized, and polymerized. Particularly, the monomaleamic acid derived from 4,4'-diaminodiphenylmethane, reacted with the monofurfurylpyromellitamic acid to yield a triamic acid which was cyclodehydrated to the corresponding triimide. A polyimide was obtained upon heat-curing of triimide or the intermediate triamic acid. In addition, equimolar amounts of N,N'-bismaleimido-4,4'-diphenylmethane (BMDM) and bisfurfurylpyromellitimide or their intermediate diamic acids were cured to afford a polyimide. The polymer precursors were characterized by IR and ¹H-NMR spectroscopy and their curing behavior was investigated by DTA. It was shown that the Diels-Alder polymerization of monomers took place at lower temperature than that required for crosslinking of BMDM. The thermal stabilities of polymers were ascertained by TGA and isothermal gravimetric analysis (IGA). The synthesized Diels-Alder polymers were remarkably more heat-resistant than the crosslinked polymer obtained from BMDM or its intermediate bismaleamic acid. They were stable up to about 360°C in N₂ or air and afforded anaerobic char yield of 58% at 800°C. © 1992 John Wiley & Sons, Inc.     

Sulfonated liquid crystalline polyesters as resin matrix for single wall carbon nanotube and nanodiamond composites

The focus of this study is on incorporating pendant sulfonate groups along the backbone of a liquid crystalline polyester (LCPE) with the aim to improve the dispersion of single wall carbon nanotubes (SWNTs) and nanodiamonds (NDs). Two LCPE matrices, one sulfonated (LCPE‐S) and one nonsulfonated reference polymer (LCPE‐R), were successfully synthesized via a melt condensation method using aromatic and aliphatic AB, AA, and BB‐type monomers. Upon the introduction of SWNT and ND particles, the glass transition temperature (T_g) of the sulfonated LCPE increased from 21.5 °C to 41.0 °C and 41.9 °C, for SWNTs and NDs, respectively. When sulfonate groups were absent, a decrease in T_g was observed. The storage modulus (E′) followed a similar trend, i.e., E′ increased from 1.3 GPa to 5.2 GPa and 3.4 GPa, upon the addition of NDs and SWNTs. The LCPE‐S showed a lower thermal stability due to the loss of sulfonate groups, i.e. the 5% weight loss temperature (T) is ～280 °C for LCPE‐S vs. 333 °C for LCPE‐R. The decomposition temperature increased somewhat upon addition of the nanoparticles. The ability of dispersing carbon‐based nanostructures combined with an accessible melt processing window makes sulfonated LCPs attractive matrices towards preparing nanocomposites with improved thermal and mechanical properties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.