Compatibilizing effect of a graft copolymer on bacterial poly(3‐hydroxybutyrate)/poly(methyl methacrylate) blends

Blends of isotactic (natural) poly(3‐hydroxybutyrate) (PHB) and poly(methyl methacrylate) (PMMA) are partially miscible, and PHB in excess of 20 wt % segregates as a partially crystalline pure phase. Copolymers containing atactic PHB chains grafted onto a PMMA backbone are used to compatibilize phase‐separated PHB/PMMA blends. Two poly(methyl methacrylate‐g‐hydroxybutyrate) [P(MMA‐g‐HB)] copolymers with different grafting densities and the same length of the grafted chain have been investigated. The copolymer with higher grafting density, containing 67 mol % hydroxybutyrate units, has a beneficial effect on the mechanical properties of PHB/PMMA blends with 30–50% PHB content, which show a remarkable increase in ductility. The main effect of copolymer addition is the inhibition of PHB crystallization. No compatibilizing effect on PHB/PMMA blends with PHB contents higher than 50% is observed with various amounts of P(MMA‐g‐HB) copolymer. In these blends, the graft copolymer is not able to prevent PHB crystallization, and the ternary PHB/PMMA/P(MMA‐g‐HB) blends remain crystalline and brittle. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1390–1399, 2002     

Fluorine‐containing linear block terpolymers: Synthesis and self‐assembly in solution

Linear triblock terpolymers of poly(n‐butyl methacrylate)‐b‐poly(methyl methacrylate)‐b‐poly(2‐fluoroethyl methacrylate) (PnBMA‐PMMA‐P2FEMA) were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization. Kinetic studies of the homopolymerization of 2FEMA by RAFT polymerization demonstrated controllable characteristics with fairly narrow polydispersities (～1.30). The resultant PnBMA‐PMMA‐P2FEMA triblock terpolymers were characterized via ¹H NMR, ¹⁹F NMR, and gel permeation chromatography. These polymers formed micellar aggregates in a selective solvent mixture. The as‐formed micelles were analyzed using scanning electron microscopy and dynamic light scattering. It was found that these terpolymers could directly self‐organize into complex micelles in a tetrahydrofuran/methanol mixture with diameters that depended on polymer composition. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Structure and Surface Properties of High-density Polyelectrolyte Brushes at the Interface of Aqueous Solution

Zwitterionic and cationic polyelectrolyte brushes were prepared by surface-initiated atom transfer radical polymerization of 2-methacryloyloxy- ethyl phosphorylcholine (MPC) and 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), respectively. The poly(DMAEMA) brush was treated with methyl iodide to form poly[2-(methacryloyloxy) ethyltrimethylammonium iodide] [poly(METAI)]. The effects of ionic strength on brush structure and surface properties of densely grafted polyelectrolyte brushes were analyzed by contact angle measurements, neutron reflectivity (NR) and macroscopic friction tests. Both polyelectrolyte brushes exhibited hydrophilic properties. The contact angle of the poly(MPC) brush surface against water was ca. 0° in air and the contact angle of the air bubble in water was ca. 170°. The air bubble in water hardly attached to the poly(MPC) brush surface, indicating super hydrophilic characteristics. NR measurements of poly(MPC) and poly(METAI) brushes showed that the grafted polymer chains were extended from the substrate surface in a good solvent such as water. Interestingly, NR study did not reveal the shrinkage of the brush chain in salt solution. The polyelectrolyte brushes immersed in both water and NaCl solution at various concentrations showed a low friction coefficient and low adhesion force.     

Interpenetrating polymer networks of poly(dimethyl siloxane–urethane) and poly(methyl methacrylate)

Simultaneous IPNs of poly(dimethyl siloxane-urethane) (PDMSU)/poly(methyl methacrylate) (PMMA) and related isomers have been prepared by using new oligomers of bis(β-hydroxyethoxymethyl)poly(dimethyl siloxane)s (PDMS diols) and new crosslinkers biuret triisocyanate (BTI) and tris(β-hydroxylethoxymethyl dimethylsiloxy) phenylsilane (Si-triol). Their phase morphology have been characterized by DSC and SEM. The SEM phase domain size is decreased by increasing crosslink density of the PDMSU network. A single phase IPN of PDMSU/PMMA can be made at an M_c = 1000 and 80 wt % of PDMSU. All of the pseudo- or semi-IPNs and blends of PDMSU and PMMA were phase separated with phase domain sizes ranging from 0.2 to several micrometers. The full IPNs of PDMSU/PMMA have better thermal resistance compared to the blends of linear PDMSU and linear PMMA. © 1993 John Wiley & Sons, Inc.     

Autonomous Volume Transitions of a Polybase Triblock Copolymer Gel in a Chemically Driven pH-Oscillator

Summary: A pH-responsive ABA triblock copolymer, comprising poly(methyl methacrylate)-block-poly(2-(diethylamino)ethyl methacrylate)-block-poly(methyl methacrylate) [PMMA-b-PDEA-b-PMMA], has been cast into thin films with a well-defined microstructure. Small Angle X-ray Scattering (SAXS) and Atomic Force Microscopy (AFM) studies confirm that this copolymer forms a hydrogel consisting of PMMA spheres embedded within a polybase PDEA matrix, with the PMMA domains acting as physical cross-links. The hydrogel has a pH-reversible coil-globule transition at around pH 4.5. This responsive physical property was exploited by immersing a sample of copolymer hydrogel in an aqueous solution containing a cyclic pH-oscillating reaction, whereby the pH was continuously oscillated above and below the transition pH so as to induce autonomous volume transitions. The changes in microscopic and macroscopic length scales correlate closely during (de)swelling cycles, with affine behaviour occurring over five orders of magnitude.     

Characterization and degradation of the poly(methylphenylsiloxane)–poly(methyl methacrylate) graft copolymer

Poly(methylphenylsiloxane)–poly(methyl methacrylate) graft copolymers (PSXE-g-PMMA) were prepared by condensation reaction of poly(methylphenylsiloxane)-containing epoxy resin (PSXE) with carboxyl-terminated poly(methyl methacrylate) (PMMA), and they were characterized by gel permeation chromatography (GPC), infrared (IR), and ²⁹Si and ¹³C nuclear magnetic resonance (NMR). The microstructure of the PSXE-g-PMMA graft copolymer was investigated by proton spin–spin relaxation T₂ measurements. The thermal stability and apparent activation energy for thermal degradation of these copolymers were studied by thermogravimetry and compared with unmodified PMMA. The incorporation of poly(methylphenylsiloxane) segments in graft copolymers improved thermal stability of PMMA and enhanced the activation energy for thermal degradation of PMMA. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2521–2530, 1998     

A Simple Way for Synthesis of Alkyne-Telechelic Poly(methyl methacrylate) via Single Electron Transfer Radical Coupling Reaction

The telechelic α,ω‐alkyne‐poly(methyl methacrylate) (alkyne‐PMMA‐alkyne) was synthesized by single electron transfer radical coupling (SETRC) reaction of α‐alkyne, ω‐bromine‐poly(methyl methacrylate) (alkyne‐ PMMA‐Br). The propargyl 2‐bomoisobutyrate (PgBiB) was first prepared to initiate atom transfer radical polymerization (ATRP) of methyl methacrylate at 45°C using CuCl/1,1,4,7,10,10‐hexamethyl triethylenetetramine (HMTETA) as homogeneous catalytic system. Then the SETRC reaction was conducted at room temperature in the presence of nascent Cu(0) and N,N,N′,N′ ′,N′ ′‐pentamethyldiethyllenetriamine (PMDETA). The precursor alkyne‐PMMA‐Br and coupled product alkyne‐PMMA‐alkyne were characterized by GPC and ¹H NMR in detail.     

Ionic conductivity and compatibility studies of blends of poly(methyl methacrylate) and poly(propylene glycol) complexed with LICF3SO3

Stable to atmospheric moisture, adhesive and transparent polymer electrolytes have been prepared by blending poly(methyl methacrylate) (PMMA) with poly(propylene glycol)-425/LiCF₃SO₃ complexes. The blending of the polymers has been achieved by a method developed in our laboratory: free radical polymerization of methylmethacrylate in the polyether/salt matrix. A series of polymer blend complexes varying in PMMA content (up to 20% by weight) and oxygen/metal ratios (25, 16, and 8) have been synthesized and their properties studied. All the samples prepared in this study were found to be optically clear unlike the higher molecular weight poly(propylene glycol)-2000 (PPG-2000) system which required a minimum salt concentration to compatibilize a specific amount of PMMA with PPG. The mechanisms by which the salt holds the otherwise incompatible polymers together in a single phase have been investigated by FT-IR. Our studies show a weak coupling of the ether oxygens in the PPG with the ester groups of the PMMA through the lithium cations. Discrete changes has been observed in the FT-IR spectrum of PMMA when doped with the lithium salt hitherto unnoticed with other dopants. Gel permeation chromatography results of the PMMA samples isolated from the solid electrolytes indicate the molecular weight to vary between 43000 and 121000 with relatively narrow distributions, 1.6?2.0. The ionic conductivities of the polymer blend electrolytes were fairly high (10^?5 S/cm) at room temperature. The PMMA neither significantly influenced the T_g of the blend complexes nor effected the ionic conductivities drastically. The ionic conductivity as a function of temperature followed the empirical Vogel-Tammann-Fulcher equation. The blending of PMMA with PPG/LiCF₃SO₃ complexes was found to impart good adhesiveness to the solid electrolytes while making them stable to atmospheric moisture. © 1992 John Wiley & Sons, Inc.     

Synthesis of core/shell structure of glycidyl–functionalized poly(methyl methacrylate) latex nanoparticles via differential microemulsion polymerization

The differential microemulsion polymerization technique was used to synthesize the nanoparticles of glycidyl-functionalized poly(methyl methacrylate) or PMMA via a two-step process, by which the amount of sodium dodecyl sulfate (SDS) surfactant required was 1/217 of the monomer amount by weight and the surfactant/water ratio could be as low as 1/600. These surfactant levels are extremely low in comparison with those used in a conventional microemulsion polymerization system. The glycidyl-functionalized PMMA nanoparticles are composed of nanosized cores of high molecular weight PMMA and nano-thin shells of the random copolymer poly[(methyl methacrylate)-ran-(glycidyl methacrylate)]. The particle sizes were about 50 nm. The ratios of the glycidyl methacrylate in the glycidyl-functionalized PMMA were achieved at about 5–26 wt.%, depending on the reaction conditions. The molecular weight of glycidyl-functionalized PMMA was in the range of about 1 × 10⁶ to 3 × 10⁶ g mol⁻¹. The solid content of glycidyl-functionalized PMMA increased when the amount of added glycidyl methacrylate was increased. The glycidyl-functionalized polymer on the surface of nano-seed PMMA nanoparticles was a random copolymer which was confirmed by ¹H-NMR spectroscopy. The amounts of functionalization were investigated by the titration of the glycidyl functional group. The structure of the glycidyl-functionalized PMMA nanoparticles was investigated by means of TEM. The glycidyl-functionalized PMMA has two regions of T_g which are at around 90 °C and 125 °C, respectively, of which the first one was attributed to the poly[(methyl methacrylate)-ran-(glycidyl methacrylate)] and the second one was due to the PMMA. A core/shell structure of the glycidyl-functionalized PMMA latex nanoparticles was observed.     

Microstructural study of poly(methyl methacrylate-co-n-propyl acrylate) by 13C NMR

Analysis of carbonyl and β-CH₂ signals in the 100?MHz ¹³C NMR spectra of poly(methyl methacrylate-co-n-propyl acrylate) (PMMA/nPrA), provided distribution of configurational-compositional sequences for a series of the copolymer samples of different composition at pentad level for carbonyl signal and hexad level for the backbone methylene carbons. Computer simulation of the spectra based on incremental calculation of the chemical shifts for individual sequences provided very good agreement with the experimental spectra.     

Rare‐earth‐metal‐initiated polymerizations of (meth)acrylates and block copolymerizations of olefins with polar monomers

The organo‐rare‐earth‐metal‐initiated living polymerization of methyl methacrylate (MMA) was first discovered in 1992 with (C₅Me₅)₂LnR (where R is H or Me and Ln is Sm, Yb, Y, or La) as an initiator. These polymerizations provided highly syndiotactic (>96%) poly(methyl methacrylate) (PMMA) with a high number‐average molecular weight (M_n > 1000 × 10³) and a very narrow molecular weight distribution [weight‐average molecular weight/number‐average molecular weight (M_w/M_n) < 1.04] quantitatively in a short period. Bridged rare‐earth‐metallocene derivatives were used to perform the block copolymerization of ethylene or 1‐hexene with MMA, methyl acrylate, cyclic carbonate, or ?‐caprolactone in a voluntary ratio. Highly isotactic (97%), monodisperse, high molecular weight (M_n > 500 × 10³, M_w/M_n < 1.1) PMMA was first obtained in 1998 with [(Me₃Si)₃C]₂Yb. Stereocomplexes prepared by the mixing of the resulting syndiotactic and isotactic PMMA revealed improved physical properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 1955–1959, 2001     

Adsorption of protein on the surface of thermosensitive poly(methyl methacrylate) microspheres modified with the N-(2-hydroxypropyl)methacrylamide and 2-(methacryloyloxy)ethyl phosphorylcholine moieties

A series of microspheres composed of methyl methacrylate (MMA) and N-(2-hydroxypropyl)methacrylamide (HPMA), and/or 2-(methacryloyloxy)ethyl phosphorylcholine (MPC), i.e., binary copolymer microspheres [poly(HPMA-co-MMA)_KPS and poly(HPMA-co-MMA)_ABIP] and ternary ones [poly(HPMA/MPC-co-MMA)_KPS and poly(HPMA/MPC-co-MMA)_ABIP], were prepared by emulsifier-free emulsion copolymerization using potassium peroxodisulfate (KPS) or 2,2′-azobis[2-(imidazolin-2-yl)propane] dihydrochloride (ABIP) as initiators. The decrease in ζ-potential of the polymer microspheres is caused by the addition of the HPMA and/or MPC moieties. Equilibrium water content of poly(HPMA-co-MMA)_ABIP showed a remarkable swelling change with a change in response to temperature: the hydrated conformation at 28°C and the dehydrated one at above 40°C. The adsorption of protein on the polymer microspheres also changed in response to change in temperature. The ternary polymer microspheres effectively suppressed the adsorption both of Alb and Glo, less than binary ones. A series of polymer microspheres are expected to apply as a novel drug carrier with both thermosensitive and nonthrombogenic functions. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3349–3357, 1997     

Synthesis and characterization of near‐monodisperse electron acceptor homopolymers of 2‐[(3,5‐dinitrobenzoyl)oxy]ethyl methacrylate

Homopolymers of 2‐(trimethylsiloxy)ethyl methacrylate of degrees of polymerization from 5 to 50 were synthesized by group transfer polymerization in tetrahydrofuran (THF) using 1‐methoxy‐1‐(trimethylsiloxy)‐2‐methyl propene as the initiator and tetrabutylammonium bibenzoate as the catalyst. These polymers were first converted to poly[2‐(hydroxy)ethyl methacrylate]s by removal of the trimethylsilyl‐protecting groups by acidic hydrolysis, and subsequently transformed to poly{2‐[(3,5‐dinitrobenzoyl)oxy]ethyl methacrylate}s by reaction with 3,5‐dinitrobenzoyl chloride in the presence of triethylamine. Gel permeation chromatography in THF and proton nuclear magnetic resonance (¹H NMR) spectroscopy in CDCl₃ and d₆ dimethyl sulfoxide were used to characterize the polymers in terms of their molecular weight and composition. The molecular weights were found to be close to the values expected from the polymerization stoichiometry and the molecular weight distributions were narrow, with polydispersity indices around 1.1. The hydrolysis and reesterification steps were found to be almost quantitative for all polymers. Differential scanning calorimetry and thermal gravimetric analysis were also employed to measure the glass transition temperatures (T_g 's) and decomposition temperatures, which were determined to be approximately 80 and 320 °C, respectively. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1457–1465, 2000     

Investigation at the chain segmental level of the miscibility of poly(vinyl chloride)/atactic poly(methyl methacrylate) blends

We employed high‐resolution ¹³C cross‐polarization/magic‐angle‐spinning/dipolar‐decoupling NMR spectroscopy to investigate the miscibility and phase behavior of poly(vinyl chloride) (PVC)/poly(methyl methacrylate) (PMMA) blends. The spin–lattice relaxation times of protons in both the laboratory and rotating frames [T₁(H) and T_1ρ(H), respectively] were indirectly measured through ¹³C resonances. The T₁(H) results indicate that the blends are homogeneous, at least on a scale of 200–300 Å, confirming the miscibility of the system from a differential scanning calorimetry study in terms of the replacement of the glass‐transition‐temperature feature. The single decay and composition‐dependent T_1ρ(H) values for each blend further demonstrate that the spin diffusion among all protons in the blends averages out the whole relaxation process; therefore, the blends are homogeneous on a scale of 18–20 Å. The microcrystallinity of PVC disappears upon blending with PMMA, indicating intimate mixing of the two polymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2390–2396, 2001     

Microstructure of poly(methyl methacrylate-co-isopropyl acrylate) studied by 13C NMR

The distribution of configurational–compositional sequences of poly(methyl methacrylate-co-isopropyl acrylate) (PMMA/iPrA) has been determined from the carbonyl and β-CH₂ signals in the 100?MHz ¹³C NMR spectra of the copolymer. The carbonyl signal provided information on configurational–compositional sequences up to heptads, whereas β-CH₂ signals offered complementary information on even sequences up to hexads. The assignment of the sequences to the respective signals was based on a comparison with the spectra of respective homopolymers, that is, PMMA and PiPrA followed by a computer simulation applying an incremental calculation of chemical shifts of the individual sequences.     

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry investigations of polystyrene and poly(methyl methacrylate) produced by monoacylphosphine oxide photoinitiation

The chain-end-group composition was determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses of low-molecular-weight polystyrene (PS) and poly(methyl methacrylate) (PMMA) produced by free-radical polymerization with a monoacylphosphine oxide, (2,4,6-trimethylbenzoyl) diphenylphosphine oxide (TPO), as a photoinitiator. Gel permeation chromatography (GPC) fractionation of the PS and PMMA samples with initial polydispersities of 1.81 and 2.81, respectively, yielded improved MALDI-TOF MS spectra. Spectral analyses of the PS fractions showed distributions attributable to PS having two diphenylphosphinyl ends and PS having one diphenylphosphinyl end and/or one 2,4,6-trimethylbenzoyl end, indicating that a combination of PS radicals with the highly reactive diphenylphosphine oxide group at one end of the chains was the predominant mode of termination. MALDI-TOF MS results for PMMA fractions provided evidence for termination primarily by disproportionation, but structure determination was confounded by the presence of isobaric peaks. Discernible peaks were obtained by MALDI-TOF MS analyses of GPC fractions of TPO-initiated poly(methyl-d₃ methacrylate-d₅), in which the major product was PMMA with a diphenylphosphinyl end group and an abstracted deuterium end group, whereas the minor combination product had two diphenylphosphinyl chain ends. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2161–2171, 2007     

Miscibility and phase structure of binary blends of polylactide and poly(methyl methacrylate)

Blends of amorphous poly(DL‐lactide) (DL‐PLA) and crystalline poly(L‐lactide) (PLLA) with poly(methyl methacrylate) (PMMA) were prepared by both solution/precipitation and solution‐casting film methods. The miscibility, crystallization behavior, and component interaction of these blends were examined by differential scanning calorimetry. Only one glass‐transition temperature (T_g) was found in the DL‐PLA/PMMA solution/precipitation blends, indicating miscibility in this system. Two isolated T_g's appeared in the DL‐PLA/PMMA solution‐casting film blends, suggesting two segregated phases in the blend system, but evidence showed that two components were partially miscible. In the PLLA/PMMA blend, the crystallization of PLLA was greatly restricted by amorphous PMMA. Once the thermal history of the blend was destroyed, PLLA and PMMA were miscible. The T_g composition relationship for both DL‐PLA/PMMA and PLLA/PMMA miscible systems obeyed the Gordon–Taylor equation. Experiment results indicated that there is no more favorable trend of DL‐PLA to form miscible blends with PMMA than PLLA when PLLA is in the amorphous state. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 23–30, 2003     

Synthesis of carbosilane block copolymers by means of a living anionic polymerization of 1,1-diethylsilacyclobutane

Block polymerization of 1,1-diethylsilacyclobutane with styrene derivatives and methacrylate derivatives was investigated. Sequential addition of styrene to a living poly(1,1-diethylsilabutane), which was prepared from phenyllithium and 1,1-diethylsilacyclobutane in THF–hexane at −48°C, gave poly(1,1-diethylsilabutane)-b-polystyrene. Similarly, addition of 4-(tert-butyldimethylsiloxy)styrene to the living poly(1,1-diethylsilabutane) provided poly(1,1-diethylsilabutane)-b-poly(4-(tert-butyldimethylsiloxy)styrene). Poly(1,1-diethylsilabutane)-b-poly(methyl methacrylate) was obtained by treatment of living poly(1,1-diethylsilabutane) with 1,1-diphenylethylene followed by an addition of methyl methacrylate. Poly(1,1-diethylsilabutane)-b-poly(2-(tert-butyldimethylsiloxy)ethyl methacrylate) was also synthesized by adding 2-(tert-butyldimethylsiloxy)ethyl methacrylate to the living poly(1,1-diethylsilabutane) which was end-capped with 1,1-diphenylethylene in the presence of lithium chloride. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2699–2706, 1998     

Novel core-shell nanoparticles and their application in high-capacity immobilization of enzymes

Novel core-shell nanoparticles consisting of poly(methyl methacrylate) (PMMA) cores coated with synthetic polymer and biopolymer (polyethyleneimine, chitosan, and casein) shells were synthesized via direct graft copolymerization of methyl methacry late from hydrophilic polymers in the absence of surfactant. Average hydrodynamic diameters of the nanoparticles ranged from 163 to 263 nm. High-capacity (up to 530 mg/g) immobilizations of enzymes and high-activity retained percentage (E _spe) (up to 90%) were achieved.     

Thermal stability of porous it‐PMMA thin film obtained by the extraction of st‐PMAA from it‐PMMA/st‐PMAA stereocomplex with layer‐by‐layer assembly on a substrate

The functionality of porous isotactic (it) poly(methyl methacrylate) (PMMA) thin films, which were previously developed by the selective extraction of syndiotactic (st) poly(methacrylic acid) (PMAA) from the it‐PMMA/st‐PMAA stereocomplex thin film on a substrate using the layer‐by‐layer assembly method was investigated after thermal treatment (70, 80, and 90 °C) in water for 4 h. Quartz crystal microbalance analysis and infrared spectra measurements revealed that the st‐PMAA incorporation ability of the porous it‐PMMA thin film decreased in order at 80 and 90 °C, while there was no decrease observed at 70 °C. X‐ray diffraction analysis also supported the thermal stability of the porosity at 70 °C, whereas two it‐PMMA crystalline peaks (2θ = 9° and 14°) were generated during heating at 90 °C. The loss of the functionality of the it‐PMMA thin film was thus shown to be due to crystallization, which was caused by the increase in polymer‐chain mobility during the heating process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3265–3270, 2010