The conformation of poly(3-dodecyl thiophene) within methacrylic polymer matrix

Blends of poly(3-dodecyl thiophene) (PDDT) with poly(methyl methacrylate), poly(butyl methacrylate) (PBMA), and poly(methyl methacrylate-co-butyl methacrylate) (PMMA/PBMA) were studied by polarization optical microscopy, atomic-force microscopy, and absorption spectroscopy and were modeled using molecular dynamics (MD) simulations. The observed thermochromic transitions are shown to be host-matrix dependent, with PDDT/PBMA absorption spectra differing substantially from pristine PDDT. The dispersion of PDDT within PBMA matrix is observed to be greater than in the other host polymers. MD calculations of both individual PDDT molecules and molecular aggregates suggest that the distribution of dihedral angles present in the PDDT backbone is the narrowest for aggregates of PDDT embedded within a polymer matrix. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2909–2917, 1999     

Post-lactonization of vinyl polymers containing pendent ester and hydroxymethyl groups

Copolymers of methyl methacrylate with methyl and ethyl α-hydroxymethylacrylate and with α-hydroxymethylstyrene have been prepared with free-radical initiators at temperatures below 80°C. At higher reaction temperatures or under extrusion conditions, alcohol was eliminated and the free hydroxyl content was greatly decreased. All evidence indicates the formation of six-membered lactone groups in this post-polymerization reaction: direct evidence for their formation is lacking, however, since neither infrared nor nuclear magnetic resonance spectra could be used to detect lactonization in this system. The loss of activity from ¹⁴C ester-labeled methyl methacrylate copolymer on heating could be correlated with the extent of lactonization. The degree of lactonization is relatively less with copolymers containing higher amounts of hydroxymethyl groups. The resulting polymers exhibit higher heat distortion temperatures and decreased impact resistance when compared to poly(methyl methacrylate). Attempts were made to incorporate similar lactone structures by cyclocopolymerization with methyl methacrylate of α-methacryloxymethylstyrene or ethyl α-methacryloxymethylacrylate, but only crosslinked polymers or polymers with pendent unsaturation were found.     

Immiscibility,upper critical solution temperature,and miscibility in blends of poly(vinyl ether)s with polyacrylics: Effects of pendant groups

Various phase behavior of blends of poly(vinyl ether)s with homologous acrylic polymers (polymethacrylates or polyacrylates) were examined using differential scanning calorimetry, optical microscopy (OM), and Fourier‐transformed infrared spectroscopy. Effects of varying the pendant groups of either of constituent polymers on the phase behavior of the blends were analyzed. A series of interestingly different phase behavior in the blends has been revealed in that as the pendant group in the acrylic polymer series gets longer, polymethacrylate/poly(vinyl methyl ether) (PVME) blends exhibit immiscibility, upper critical solution temperature (UCST), and miscibility, respectively. This study found that the true phase behavior of poly(propyl methacrylate)/PVME [and poly(isopropyl methacrylate)/PVME)] blend systems, though immiscible at ambient, actually displayed a rare UCST upon heating to higher temperatures. Similarly, as the methyl pendant group in PVE is lengthened to ethyl (i.e., PVME replaced by PVEE), phase behavior of its blends with series of polymethacrylates or polyacrylates changes correspondingly. Analyses and quantitative comparisons on four series of blends of PVE/acrylic polymer were performed to thoroughly understand the effects of pendant groups in either polyethers (PVE's) or acrylic polymers on the phase behavior of the blends of these two constituents. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1521–1534, 2007     

Synthesis and propeller–propeller transition of optically active poly(diphenyl-o-tolylmethyl methacrylate)

Diphenyl-o-tolymethyl methacrylate (DPTMA) was synthesized and polymerized using initiators of organolithium complexes with (+)-(2S,3S)-dimethoxy-1,4-bis(dimethylamino) butane (DDB) and (?)-sparteine (Sp) as the chiral ligands. DDB was suitable for its complex effective to prepare optically active poly(diphenyl-o-tolylmethyl methacrylate) (PDPTMA) with one-handed helical conformation, whereas only low-molecular weight polymer was formed when Sp was used as ligand due to the repulsive hindrance between the triarylmethyl group and the ligand. A new mutarotation propeller–propeller transition, was observed for PDPTMA from the optical rotation curves and CD spectra in THF solution. The equivalent period of PDPTMA was estimated to be 14 Å based on the x-ray diffraction. © 1993 John Wiley & Sons, Inc.     

Poly(p‐benzamide) having isopropyl‐substituted chiral tri(ethylene glycol) side Chain: Synthesis and helical conformation

Isopropyl‐substituted tri(ethylene glycol) is used as a chiral side chain of N‐substituted poly(p‐benzamide) in order to increase the difference of stability between the right‐ and left‐handed helical structures of the polymer. The target polymer is synthesized by the chain‐growth condensation polymerization of the corresponding monomer with an initiator using lithium 1,1,1,3,3,3‐hexamethyldisilazide as a base. A circular dichroism (CD) study of the polymer reveals that the CD signal is due to an excess of a thermodynamically controlled right‐handed helical structure of the polymer, and that the replacement of the methyl group with a bulkier isopropyl group at the side chain of poly(p‐benzamide) increases the abundance of right‐handed helical structure in chloroform. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1623–1628     

Radical Polymerization and Copolymerization of Methyl α-(Fluoroalkoxymethyl)acrylates and Characterization of Their Polymers

Abstract

Representatives of a new type of fluorine-containing monomer, methyl α-(fluoroalkoxymethyl)acrylates (MCFMA's), were prepared. The fluoroalkoxy groups introduced were OCH₂CF₃, OCH₂CF₂CF₂H, and OCH(CF₃)₂. All the monomers synthesized readily polymerized to number-average molecular weights of 55,000 to 110,000 at a 2 mol/L monomer concentration in dioxane using 5 × 10^?3 mol/L of 2,2′-azobisisobutyronitrile at 60°C. The polymerization rate tended to decrease slightly with an increase in the size of the alkoxy group. Copoly-merization of MCFMA's with styrene revealed that the fluoroalkoxy-methyl group functions as an electron-attracting group depending on the number of fluorine atoms. According to thermogravimetric analysis, poly(MCFMA)'s were thermally less stable than poly(methyl methacrylate). Greater contact angles of the polymers from MCFMA's with water than poly(methyl methacrylate) were observed.     

Complex refractive indexes for polymers over the infrared spectral region: Specular reflection IR spectra of polymers

A dispersion analysis is used to determine the complex refractive indexes over the infrared for the following polymeric systems: isotactic poly(methyl methacrylate), syndiotactic poly(methyl methacrylate), poly(2-methyl-1-pentene)sulfone, poly(perfluoropropylene oxide), poly(pyromellitimide), poly(styrene), and poly(vinyl alcohol). These were combined with solutions of Maxwell's equations for electromagnetic radiation at interfaces in a FORTRAN computer code to model specular relection infrared spectra. Calculations and experimental data are compared to demonstrate the complicated nature of specular reflection and the ability of the modelling to simulate the observed spectra.     

Preparation and characterization of optically active polymers containing pendent and terminal chiral units via atom transfer radical polymerization

Optically active homopolymers and copolymers, bearing chiral units at the side chain and end chain, were prepared via atom transfer radical polymerization (ATRP) techniques. The well‐defined optically active polymers were obtained via the ATRP of pregnenolone methacrylate (PR‐MA), β‐cholestanol acrylate (CH‐A), and 20‐(hydroxymethyl)‐pregna‐1,4‐dien‐3‐one acrylate (HPD‐A) with ethyl 2‐bromopropionate as the initiator and CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalytic system. The experimental results showed that the polymerizations of PR‐MA, CH‐A, and HPD‐A proceeded in a living fashion, providing pendent chiral group polymers with low molecular weight distributions and predetermined molecular weights that increased linearly with the monomer conversion. Furthermore, the copolymers poly(pregnenolone methacrylate)‐b‐poly[(dimethylamino)ethyl methacrylate] and poly(pregnenolone methacrylate‐co‐methyl methacrylate) were synthesized and characterized with ¹H NMR, transmission electron microscopy, and polarimetric analysis. In addition, when optically active initiators estrone 2‐bromopropionate and 20‐(hydroxymethyl)‐pregna‐1,4‐dien‐3‐one 2‐bromopropionate were used for ATRPs of methyl methacrylate and styrene, terminal optically active poly(methyl methacrylate) and polystyrene were obtained. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1502–1513, 2006     

Slow ester side‐group flips in glassy poly(alkyl methacrylate)s characterized by centerband‐only detection of exchange nuclear magnetic resonance

Slow side‐group dynamics in a series of five poly(alkyl methacrylate)s with various side‐group sizes [poly(methacrylic acid) (PMAA), poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), poly(isobutyl methacrylate) (PiBMA), and poly(cyclohexyl methacrylate), with ? H, ? CH₃, ? CH₂CH₃, ? CH₂CH(CH₃)₂, and ? cyclohexyl alkyl substituents (CODEX), respectively] were studied quantitatively by centerband‐only detection of exchange nuclear magnetic resonance (NMR). Flips and small‐angle motions of the ester groups associated with the β relaxation were observed distinctly in the CODEX NMR data, and the fraction of slowly flipping groups was measured with a precision of 3%. In PMMA, 34% of the side groups flipped on a 1‐s timescale, whereas the fraction was 31% in PEMA at 25 °C. Even the large isobutylether and cyclohexylester side groups flipped in the glassy state, although the flipping fraction was reduced to 22 and about 10%, respectively. In PMAA, no slow side‐group flips were detected on the 1‐s timescale. A striking difference in the temperature dependence of the flipping fraction in PMMA versus PEMA and PiBMA was observed. In PMMA, the flipping fraction was temperature‐independent between 25 and 80 °C, whereas in PEMA, it increased continuously from 31 to 60% between 25 and 60 °C. A similar doubling was also observed in PiBMA. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2444–2453, 2001     

ESCA study of the surface photo-oxidation of some non-aromatic polymers

Changes in the surface composition and structure of a number of non-aromatic polymers subjected to ultraviolet irradiation in oxygen (～ 1 atm., 20°C) have been studied. No changes in surface composition were detected after photo-oxidation of poly(vinylidene fluoride) (12 h of irradiation), low density polyethylene (7·5 h) or high density polyethylene (22·3 h). This reflects the absence in these polymers of an efficient ultraviolet absorber to initiate the photo-oxidation. The surfaces of poly(methyl methacrylate) and nylon 66 show an increase in oxygen content following irradiation. In these polymers this added oxygen is present principally as carboxyl groups and, in the case of poly(methyl methacrylate), as carbonyl groups. In nylon, there is no evidence for changes in the amide group and no oxidation of the nitrogen is detected.     

Linear polymers of allyl acrylate and allyl methacrylate

Allyl acrylate and allyl methacrylate were polymerized by anionic initiators to soluble linear polymers containing allyl groups in the pendant side chains. The pendant unpolymerized allyl groups of the resulting linear poly(allyl acrylates) were shown to be present by: (1) the disappearance of the acrylyl and methacrylyl double bond absorptions in the infrared spectra in the conversions of monomers to polymers; (2) postbromination of the allyl bonds in the linear polymer; (3) the disappearance of the allyl groups absorptions in the infrared spectra of the brominated linear polymers; and (4) the thermal- and radical-initiated crosslinking of the linear polymers through the allyl groups. Allyl acrylate and allyl methacrylate show great reluctance to copolymerize with styrene under anionic initiation, but copolymerize readily with methyl methacrylate and acrylonitrile. Block copolymers were prepared by reacting allyl methacrylate with preformed polystyrene and poly(methyl methacrylate) anions. The linear polymers and copolymers of allyl acrylate may be classified as “self-reactive” polymers which yield thermosetting polymers. Bromination of the linear polymers offers a convenient method of producing self-extinguishing polymers.     

Hot embossing and thermal bonding of poly(methyl methacrylate) microfluidic chips using positive temperature coefficient ceramic heater

As a self-regulating heating device, positive temperature coefficient ceramic heater was employed for hot embossing and thermal bonding of poly(methyl methacrylate) microfluidic chip because it supplied constant-temperature heating without electrical control circuits. To emboss a channel plate, a piece of poly(methyl methacrylate) plate was sandwiched between a template and a microscopic glass slide on a positive temperature coefficient ceramic heater. All the assembled components were pressed between two elastic press heads of a spring-driven press while a voltage was applied to the heater for 10 min. Subsequently, the embossed poly(methyl methacrylate) plate bearing negative relief of channel networks was bonded with a piece of poly(methyl methacrylate) cover sheet to obtain a complete microchip using a positive temperature coefficient ceramic heater and a spring-driven press. High quality microfluidic chips fabricated by using the novel embossing/bonding device were successfully applied in the electrophoretic separation of three cations. Positive temperature coefficient ceramic heater indicates great promise for the low-cost production of poly(methyl methacrylate) microchips and should find wide applications in the fabrication of other thermoplastic polymer microfluidic devices.     

Synthesis of New Graft Copolymers by Combining the DPE Technique and Cationic Polymerization

The synthesis of a new macroinitiator for cationic polymerization via radical polymerization is presented. The macroinitiator, consisting of poly(methyl methacrylate)‐block‐poly[styrene‐co‐(4‐chloromethylstyrene)], was synthesized by heating poly(methyl methacrylate), prepared in the presence of 1,1‐diphenylethylene, in a mixture of styrene and 4‐chloromethylstyrene to 85°C without any additional initiator. The resulting macroinitiator could be used for the cationic polymerization of isobutylene yielding graft copolymers.     

Block copolymers of thiophene-capped poly(methyl methacrylate) with pyrrole

Poly(methyl methacrylate) with a thiophene end group having narrow polydispersity was prepared by the Atom Transfer Radical Polymerization (ATRP) technique. Subsequently, electrically conducting block copolymers of thiophene-capped poly(methyl methacrylate) with pyrrole were synthesized by using p-toluene sulfonic acid and sodium dodecyl sulfate as the supporting electrolytes via constant potential electrolysis. Characterization of the block copolymers were performed by CV, FTIR, SEM, TGA, and DSC analyses. Electrical conductivities were evaluated by the four-probe technique. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4218–4225, 1999     

Preparation of polymer optical fibers doped with nonlinear optical active organic chromophores

We synthesized two novel organic nonlinear optical chromophores—chiral S(+)‐N‐[p‐(4‐nitrostyryl) phenyl] prolinol and non‐chiral [p‐(4‐nitrostyryl) phenyl] piperdine—as potential laser‐active dyes for photonic applications. Both materials show good optical transmittance in the telecommunication frequency region, desirable solubility in acrylic polymer optical fiber matrices, and attractive fluorescence properties that are advantageous for laser‐gain materials and devices. Subsequently, these two chromophores were incorporated into poly(methyl methacrylate) and poly(ethyl methacrylate) and drawn into polymer optical fibers. The relevant properties of these organic dye‐doped fibers have been studied, revealing essential attributes of laser‐active characteristics. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1794–1801, 2001     

Thermal degradation of phenyl methacrylate-methyl methacrylate copolymers

The degradation behaviours of poly(phenyl methacrylate), four phenyl methacrylate-methyl methacrylate copolymers which span the composition range, and poly(methyl methacrylate) have been compared by using thermogravimetry in dynamic nitrogen and thermal volatilisation analysis (TVA) under vacuum, with programmed heating at 10°C/min. Volatile products have been separated by subambient TVA and identified and the cold ring fraction and partially degraded polymer have been examined by ir spectroscopy. Poly(phenyl methacrylate) resembles poly(methyl methacrylate) in degrading completely to monomer. Copolymers of phenyl methacrylate and methyl methacrylate are more stable than the homopolymers. On degradation, the major products are the two monomers. Minor products from all the copolymers include carbon dioxide, dimethylketene, isobutene and formaldehyde. Copolymers with low and moderate phenyl methacrylate contents show the formation of anhydride ring structures in the cold ring fraction and partially degraded copolymer, together with small amounts of methanol in the volatile products. Carbon dioxide is a more significant product at lower phenyl methacrylate contents.The mechanism of degradation is discussed.     

Polymerization of adsorbed monolayers. III. Preliminary structure studies in dilute solution of the insertion polymers

Insertion poly(methyl acrylate) and poly(methyl methacrylate) were prepared from monomers adsorbed in monolayers on the surface of montmorillonite clay, both in the presence and in the absence of bifunctional crosslinkers (ethylene glycol dimethacrylate and tetramethylene glycol dimethacrylate). The insertion poly(methyl acrylate) and the crosslinked insertion poly(methyl methacrylate) and dilute-solution properties quite different from conventional polymers of these monomers, the differences including high light-scattering molecular weights combined with low viscosities, low values of the second virial coefficient, unusually large variations of the Huggins' constant k′ with the time-temperature history of the solutions, and low sedimentation velocities. These properties suggest that the insertion polymers have compact structures and are consistent with the postulate of sheetlike macromolecules. The dilute-solution properties of insertion poly(methyl methacrylate) made without crosslinker, unlike those of similarly prepared poly(methyl acrylate), were similar to those of conventional poly(methyl methacrylate). This difference in behavior is attributed to the different tendencies of the two monomers to undergo branching or crosslinking during radical polymerization.     

Synthesis,characterization and release profiles of nanoparticles self‐assembled from poly (PEGMA‐co‐MMA‐co‐acryloyl‐β‐CD) copolymers

A novel amphiphilic copolymer was synthesized from poly (ethylene glycol) methyl ether methacrylate (PEGMA950), methyl methacrylate (MMA) and acryloyl‐β‐cyclodextrin (acryloyl‐β‐CD) using the composites of (NH₄)₂S₂O₈/NaHSO₃ as the oxidation–reduction initiators. The successful fabrication of poly(PEGMA‐co‐MMA‐co‐acryloyl‐β‐CD) copolymers was confirmed by Fourier transform infrared spectrometer (FTIR), ¹H‐nuclear magnetic resonance (¹H NMR) spectra. The amphiphilic copolymer could self‐assemble into nanoparticles (NPs), and their morphology and particle size distribution were characterized with transmission electron microscopy (TEM), atomic force microscope (AFM) and dynamic light scattering (DLS) methods. Ibuprofen (IBU) was encapsulated in the novel NPs, and the release profiles of IBU were investigated. FTIR and ¹H NMR spectra illustrated that the poly(PEGMA‐co‐MMA‐co‐acryloyl‐β‐CD) copolymers were synthesized without any residual monomers and initiators. TEM and AFM photographs suggested that the obtained NPs were spherical, and the DLS results indicated that the diameter of blank NPs was 157.3 ± 32.7 nm. The IBU release profile showed that the IBU‐loaded NPs had certain pH responsibility. Copyright © 2014 John Wiley & Sons, Ltd.     

Syntheses and polymerizations of novel chiral poly(acrylamide) macromonomers and their chiral recognition abilities

Chiral poly(acrylamide) macromonomers (PMB‐1, PMB‐2, PPAE‐1, and PPAE‐2) were synthesized from 2‐methacryloyloxyethyl isocyanate and prepolymers, that is, poly[(S)‐methylbenzyl acrylamide] or poly(L ‐phenylalanine ethylester acrylamide with a terminal carboxylic acid or hydroxy group. Radical homopolymerizations of poly(acrylamide) macromonomers were carried out under several conditions to obtain the corresponding optically active polymers. A strong temperature dependence on the specific optical rotation was observed for poly(PPAE‐2) in comparison with that for the corresponding prepolymer. This might have resulted from a change in the conformation caused by hydrogen bonds between polymer‐graft branches in the polymacromonomer. Radical copolymerizations of poly(acrylamide) macromonomers with styrene and methyl methacrylate were performed with azobisisobutyronitrile in tetrahydrofuran at 60 °C. Chiroptical properties of the copolymers were slightly influenced by comonomer units. Chiral stationary phases were prepared by the radical polymerization of poly(acrylamide) macromonomers in the presence of silica gel containing vinyl groups on the surface. Some racemic compounds such as menthol and mandelic acid were resolved on the chiral stationary phases for high‐performance liquid chromatography. The conformation based on hydrogen bonds between polymer‐graft branches in the polymacromonomers may play an important role in chiral discrimination. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1726–1741, 2002     

A biocompatible block glycopolymeric dispersant: synthesis,characterization, and dispersing properties for nano-TiO2

A biocompatible block glycopolymer poly(methyl methacrylate)-b-poly(3-O-allyl-α-D-glucose) (PMAG) was employed as a polymeric dispersant for the dispersion of nano-TiO₂. PMAG was prepared from methyl methacrylate (MMA) and 3-O-allyl-1,2:5,6-di-O-isopropynylene-α-D-glucose (ADG) via reversible addition-fragmentation chain transfer (RAFT) polymerization. The obtained product was characterized by Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (¹H NMR) spectroscopy, and gel permeation chromatography (GPC). The copolymer showed good biocompatiblity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The maximum adsorption capacity for PMAG on nano-TiO₂ is 4.11 mg/g, which is in good agreement with Langmuir isotherm. Transmission electron microscopy (TEM) image indicated that nano-TiO₂ is well dispersed by PMAG. Raman and FT-IR spectra demonstrated that PMAG is absorbed onto the surface of nano-TiO₂.