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     

Metal‐free synthesis of novel biobased dihydroxyl‐terminated aliphatic polyesters as building blocks for thermoplastic polyurethanes

Using the organic compound 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) as a catalyst for step‐growth polymerization, a series of well‐defined hydroxyl‐telechelic renewable aliphatic polyesters (including poly(1,3‐propylene adipate); poly(1,4‐butylene adipate); poly(1,12‐dodecylene sebacate); and poly(1,2‐dimethylethylene adipate), PDMEA) were synthesized and studied. PDMEA is a novel polyester, which has not been reported before. The results of ¹H NMR and Matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry indicate that the polymers are fully hydroxyl terminated. From differential scanning calorimetry (DSC) thermograms, we found that the glass transition temperatures (T_g) of these polyesters are below ?20 °C. Only a T_g but no melting peak is observed in the DSC curve of the novel PDMEA. This indicates that PDMEA, contrary to the other renewable polyesters, is totally amorphous. Furthermore, using hexamethylene diisocyanate and hexamethylene diamine, poly(ester urethane urea)s (PEUUs) based on PDMEA were successfully synthesized. The T_g of the prepared PEUUs is below 0 °C, and no melting behavior of the soft‐segment is observed. The PEUU, with a flow temperature of over 200 °C, thus behaves as an elastomer at room temperature. Its mechanical properties, such as a relatively low tensile E‐modulus (≈20 MPa) at room temperature and a sufficiently high strain at break (≈560%), make it suitable for use in, for example, biomedical applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Micromechanical fast quasi‐static detection of α and β relaxations with nanograms of polymer

Micromechanical string resonators are used as a highly sensitive tool for the detection of glass transition (T_g or α relaxation) and sub‐T_g (β relaxation) temperatures of polystyrene (PS) and poly (methyl methacrylate) (PMMA). The characterization technique allows for a fast detection of mechanical relaxations of polymers with only few nanograms of sample in a quasi‐static condition. The polymers are spray coated on one side of silicon nitride (SiN) microstrings. These are pre‐stressed suspended structures clamped on both ends to a silicon frame. The resonance frequency of the microstrings is then monitored as a function of increasing temperature. α and β relaxations in the polymer affect the net static tensile stress of the microstring and result in measureable local frequency slope maxima. T_g of PS and PMMA is detected at 91 ±2°C and 114 ±2°C, respectively. The results match well with the glass transition values of 93.6°C and 114.5°C obtained from differential scanning calorimetry of PS and PMMA, respectively. The β relaxation temperatures are detected at 30 ± 2°C and 33 ± 2°C for PS and PMMA which is in accordance with values reported in literature. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1035–1039     

Effect of supercritical CO2 on the copolymerization behavior of cyclohexene oxide/CO2 and copolymer properties with DMC/Salen‐Co(III) catalyst system

The copolymerization of cyclohexene oxide (CHO) and carbon dioxide (CO₂) was carried out under supercritical CO₂ (scCO₂) conditions to afford poly (cyclohexene carbonate) (PCHC) in high yield. The scCO₂ provided not only the C1 feedstock but also proved to be a very efficient solvent and processing aid for this copolymerization system. Double metal cyanide (DMC) and salen‐Co(III) catalysts were employed, demonstrating excellent CO₂/CHO copolymerization with high yield and high selectivity. Surprisingly, our use of scCO₂ was found to significantly enhance the copolymerization efficiency and the quality of the final polymer product. Thermally stable and high molecular weight (MW) copolymers were successfully obtained. Optimization led to excellent catalyst yield (656 wt/wt, polymer/catalyst) and selectivity (over 96% toward polycarbonate) that were significantly beyond what could be achieved in conventional solvents. Moreover, detailed thermal analyses demonstrated that the PCHC copolymer produced in scCO₂ exhibited higher glass transition temperatures (T_g ～ 114 °C) compared to polymer formed in dense phase CO₂ (T_g ～ 77 °C), and hence good thermal stability. Additionally, residual catalyst could be removed from the final polymer using scCO₂, pointing toward a green method that avoids the use of conventional volatile organic‐based solvents for both synthesis and work‐up. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2785–2793     

One‐shot synthesis of high molar mass polyurethane in supercritical carbon dioxide

Well‐defined polyurethane–polydimethylsiloxane particles of tunable diameter in the range of 0.5–20 μm were synthesized in “one‐shot” by step‐growth polymerization using supercritical carbon dioxide (scCO₂) as a dispersant medium. Polymerizations were carried out at 60 °C and above 25 MPa, after the solubility of each reactant in scCO₂ has been determined in its typical reaction concentration. The synthesis of such copolymers was achieved by polyaddition between short aliphatic diols, that is, ethylene glycol, 1,4‐butanediol (BD) or polyethylene oxide (M_n = 200 g mol^?1), and tolylene‐1,4‐di‐isocyanate (TDI) in the presence of mono or di‐isocyanate‐terminated polydimethylsiloxane (PDMS) as reactive stabilizers and dibutyltin dilaurate as a catalyst. The nature of the diol used as well as the functionality of the reactive stabilizer incorporated was found to have a dramatic effect on the molar mass and the morphology of the resulting product. Thus, copolymers obtained from the polyaddition of BD and TDI in the presence of di‐isocyanate‐terminated PDMS exhibit molar mass up to 90,000 g mol^?1. Thermal behaviors of copolymers were also examined by differential scanning calorimetry. All samples exhibited only one glass transition temperature (T_g) and were found to be totally amorphous. A logical decrease of the T_g was observed as the length of the diol incorporated increased, that is, as the density of urethane linkages within the polymer decreased. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5649–5661, 2007     

Experimental and computational studies of ring‐opening polymerization of ethylene brassylate macrolactone and copolymerization with ε‐caprolactone and TBD‐guanidine organic catalyst

The ring‐opening polymerization (ROP) of ethylene brassylate, catalyzed by the cyclic guanidine 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) is reported. Several experimental parameters were evaluated for bulk ROP process and polyesters, resulting in molecular weights between 3 and 15 kg mol^?1. End‐group analysis by ¹H nuclear magnetic resonnance (NMR) and matrix assisted laser desorption ionization time of flight computational studies supports the dual behavior of TBD, which can act as both a catalyst and initiator of the polymerization process. Under optimum conditions, semicrystalline poly(ethylene brassylate‐co‐ε‐caprolactone) random copolymers were synthesized. Depending on the comonomer content, our results showed a range of melting temperatures between 39 and 69 °C. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 552–561     

Acceleration effects of 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene with 2‐methylimidazole‐intercalated α‐zirconium phosphate as a latent thermal initiator in the reaction of glycidyl phenyl ether and hexahydro‐4‐methylphthalic anhydride

The catalytic effects of 1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene (TBD) with 2‐methylimidazole‐intercalated α‐zirconium phosphate (α‐ZrP?2MIm) in the reaction of glycidyl phenyl ether (GPE) and hexahydro‐4‐methylphthalic anhydride (MHHPA) were investigated. The reaction did not proceed within 1 h at 60 °C. On increasing the temperature to 100 °C, the conversion reached 93% for 1 h. Without the addition of TBD, the conversion was 67% at 100 °C for 1 h. Under storage conditions at 25 °C for 7 days, the conversion of GPE was only 18%. The curing behavior of 2,2‐bis(4‐glycidyloxyphenyl)propane (DGEBA) and MHHPA in the presence of TBD with α‐ZrP?2MIm was evaluated by differential scanning calorimetry. The addition of TBD with α‐ZrP?2MIm as a latent thermal initiator, the storage stability was maintained and the reaction proceeded rapidly under heating conditions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2557–2561     

Ring-opening polymerization of 1,4-oxathian-2-one and its copolymerization with δ-valerolactone

Monomer 1,4-oxathian-2-one ( OX ) was synthesized by a one pot two-step method, and it was oxidized to the sulfone ester monomer, 1,4-oxathian-2-one-4,4-dioxide ( OX-SO ₂ ). Three organic catalysts, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and diphenyl phosphate (DPP) were screened for the ring-opening polymerization (ROP) of OX in dichloromethane at 30°C. It was found that OX has a high polymerizability, the TBD-catalyzed ROP is very fast but with serious side reactions, the DBU-catalyzed ROP is moderately controlled, and the DPP-catalyzed ROP is well controlled until the polymerization reach equilibrium. Bulk ROP of OX-SO ₂ was achieved with stannous octoate ((Sn[Oct]₂) at 130°C. Poly(OX) is a semicrystalline polyester (T_m = 40-60°C, T_g = −39.6°C), while Poly(OX-SO ₂ ) is a highly crystalline polyester(T_g = 55°C, T_m = 211°C with decomposition). Kinetics experiments of OX and δ-valerolactone (VL) revealed that VL polymerized faster than OX with DPP as the catalyst. Thermodynamic parameters of the ROP of OX and VL under identical conditions were measured; the ROP of OX is thermodynamically more favorable than that of VL. A series of random copolymers of OX and VL was prepared using TBD as the catalyst and confirmed that the in-chain heteroatom greatly affected the crystallization of the copolymers.     

Synthesis of trans‐4‐hydroxy‐L‐proline‐based telechelic prepolymers and poly(ester‐urethane)

The synthesis of hydroxyproline‐based telechelic prepolymers by the condensation polymerization of trans‐4‐hydroxy‐N‐benzyloxycarbonyl‐L ‐proline methyl ester was investigated. All the polymerizations were carried out in the melt with stannous octoate as the catalyst and with different diols. The products were characterized by differential scanning calorimetry, proton nuclear magnetic resonance, infrared spectrophotometry, and inherent viscosity (η_inh). According to the analytic results, the η_inh value of the prepolymers depended on the kind and amount of diols that were added. With an increase in the 1,6‐hexanediol feed from 2 to 10 mol %, there was a decrease in η_inh from 0.78 to 0.41 along with a decrease in the glass‐transition temperature (T_g ) from 63 to 42 °C. When 2 mol % of different kinds of diols were used, η_inh ranged from 0.78 to 0.21, and T_g varied from 70 to 43 °C. These new prepolymers could be linked to poly(ester‐urethane) by the chain extender 1,6‐hexamethylene diisocyanate. The poly(ester‐urethane) was amorphous, and the T_g was 76 °C. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2449–2455, 2000     

Dispersion of silica nanoparticles bearing perfluorohexyl units into fluorinated copolymers

This study aims at determining the compatibility behavior of nanoparticles surface with fluorinated matrices to obtain a homogenous dispersion and better composites properties. First, modified silica nanoparticles by C₆F₁₃I and C₆F₁₃‐C₂H₄‐SH led to various fluorinated silica of different massic concentrations and grafting rates. The dispersion of these nanoparticles (in 5 wt %) into molten poly(VDF‐co‐HFP) and poly(TFE‐co‐HFP) matrices were studied as well as the hydrophobic, mechanical, and thermal properties of both fluorinated copolymers and resulting composites. In both series, the storage modulus of nanocomposites increased while the melting (T_m) and decomposition (T_10%) temperatures varied with the polymer matrix. They increased for poly(VDF‐co‐HFP) composites (T_m= 134 to 144 °C and T_10%= 441 to 464 °C) but decreased for poly(TFE‐co‐HFP) nanocomposites (T_m= 276 to 268 °C and T_10%= 488 to 477 °C). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1512–1522     

Tailor‐made and chemically designed synthesis of coumarin‐containing benzoxazines and their reactivity study toward their thermosets

Coumarins are used as a natural renewable resource to synthesize coumarin‐containing benzoxazine resins. The coumarin‐containing benzoxazines are fully characterized in terms of their chemical structure by Fourier‐transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The influence of electronic effects caused by the substituents on the polymerization temperature is also evaluated. Thermal properties of the resulting thermosets are characterized by differential scanning calorimetry and thermogravimetric analysis, showing good stability and char yields higher than 50%. The coumarin‐containing polybenzoxazine thermosets show T_g values in the range between 160 and 190 °C. Thus, the herein presented coumarin‐containing benzoxazine resins are proven to be competitive monomers when compared with other petroleum‐based benzoxazine resins toward the generation of high‐performance thermoset. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1428‐1435     

Internal plasticization of poly(vinyl) chloride using glutamic acid as a branched linker to incorporate four plasticizers per anchor point

Internal plasticization of polyvinyl chloride (PVC) using thermal azide‐alkyne Huisgen dipolar cycloaddition between azidized PVC and electron‐poor acetylenediamides incorporating a branched glutamic acid linker resulted in incorporation of four plasticizing moieties per attachment point on the polymer chain. A systematic study incorporating either alkyl or polyethylene glycol esters provided materials with varying degrees of plasticization, with depressed T_g values ranging from ?1 °C to 62 °C. Three interesting trends were observed. First, T_g values of PVC bearing various internal plasticizers were shown to decrease with increasing chain length of the plasticizing ester. Second, branched internal plasticizers bearing triethylene glycol chains had lower T_g values compared to those with similar length long‐chain alkyl groups. Finally, thermogravimetric analysis of these internally plasticized PVC samples revealed that these branched internal plasticizers bearing alkyl chains are more thermally stable than similarity branched plasticizers bearing triethylene glycol units. These internal tetra‐plasticizers were synthesized and attached to PVC‐azide in three simple synthetic steps. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1821–1835     

Synthesis and properties of poly(sulfone‐arylate) copolymers

Poly(sulfone‐arylate) was synthesized in a reaction between dihydroxy polysulfone prepolymers and either diphenyl terephthalate or terephthaloyl chloride. The dihydroxy polysulfone prepolymers had molecular weights of 2000 and 4000 g/mol. The polymerization with diphenyl terephthalate was carried out at high temperature (280 °C) in the presence of a catalyst, whereas the polymerization with terephthalic chloride was conducted in solution at low temperature in the presence of an acid acceptor. High‐molecular weight copolymers (η_inh ～ 0.60 dL/g) could be obtained through both methods. The copolymers were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, DMA, and differential scanning calorimetry measurements and were found to exhibit high T_g values. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3904–3913, 2009     

Synthesis and properties of poly(thiourethane)s having soft oligoether segments

Polyaddition of bis(five‐membered cyclic dithiocarbonate), 2,2‐bis[4‐(1,3‐thioxolane‐2‐one‐4‐yl‐methoxy)phenyl]propane ( 1 ), with diamines having soft oligoether segments and property of the obtained poly(thiourethane)s were examined. Treatment of 1 with equivalent diamines in tetrahydrofuran at room temperature gave poly(thiourethane)s having a mercapto group in each unit, which were further treated with acetic anhydride and triethylamine to give the corresponding S‐acetylated poly(thiourethane)s in high yield. Exposing the mercapto group containing poly(thiourethane)s to benzoyl chloride and triethylamine provided the corresponding S‐benzoylated poly(thiourethane)s effectively. Thermal properties of the obtained polymers were evaluated by thermogravimetric analysis and differential scanning calorimetry. The obtained polymers showed 10 wt % loss temperature (T_d10) in the range from 230 to 274 °C, which was relatively high when compared with the T_d10 of an analogous polymer prepared from 1 and 1,6‐hexamethylenediamine. The polymers obtained here exhibited glass transition temperature (T_g) in the range from ?16 °C to 40 °C, which was much lower than the analogous polymer described above, probably due to the soft oligoether segments. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1076–1081     

A non‐phosgene process to homopolycarbonate and copolycarbonates of isosorbide using dimethyl carbonate: Synthesis,characterization, and properties

Poly(isosorbide carbonate) (PIC) was synthesized by melt polycondensation of dimethyl carbonate (DMC) and isosorbide using lithium acetylacetonate (LiAcac) as the catalyst. The reaction conditions were optimized to achieve PIC with relatively high number‐average molecular weight (M_n) of 28,800 g/mol and isosorbide conversion of 95.2%. A series of poly(aliphatic diol‐co‐isosorbide carbonate)s (PAICs) were also synthesized by melt polycondensation of DMC with isosorbide and equimolar amounts of aliphatic diols (1,4‐butanediol, 1,5‐pentanediol, 1,6‐hexanediol, and 1,4‐cyclohexane dimethanol) in the presence of LiAcac and the TiO₂/SiO₂‐based catalyst (TSP‐44). PAICs with M_n values ranging from 18,700 to 34,400 g/mol and polydispersities between 1.64 and 1.69 were obtained. The ¹³C NMR analysis revealed the random microstructure of PAICs. The differential scanning calorimetry results demonstrated that all the PAICs were amorphous with a unique T_g ranging from 46 to 88 °C. The dynamic analysis results showed that the incorporation of linear or cyclohexane structure changed the dynamic mechanical properties of PIC drastically. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

PNVCL‐PEGMA nanohydrogels with tailored transition temperature for controlled delivery of 5‐fluorouracil

Sensitive nanohydrogels were prepared via surfactant free emulsion copolymerization of N‐vinylcaprolactam and poly(ethylene glycol) methyl ether methacrylate, and either N‐vinylpyrrolidone (VP) or 2‐methacryloyloxybenzoic acid (2MBA) to adjust the transition temperature (T_tr). The crosslinker ethylene glycol dimethacrylate was used for the polymer network construction. The resulting nanohydrogel sizes are between 120 and 300 nm. ρ‐Parameter, obtained from light scattering studies, suggests that core‐sell nanogels of flexible chains were obtained. T_tr increases with increasing comonomer content (VP or 2MBA) and decreases with decreasing pH for 2MBA containing nanohydrogels. Nanohydrogels containing 15.5% of 2MBA exhibit T_tr close to 38 °C. Nanogels are able to control the release of the loaded antineoplastic drug 5‐fluorouracil. For the prepared T/pH‐sensitive nanogels, the release is slower at pH 7.4 and 37 °C than at tumor conditions: pH 6 and 40 °C. Mathematical models were applied to evaluate the kinetics of drug release; Peppas model fitted best indicating a Fickian diffusion trough a sphere. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2662–2672     

Kinetics of hexene‐1 polymerization using [(N,N′‐diisopropylbenzene)‐2,3‐(1,8‐napthyl)‐1,4‐diazabutadiene] dibromonickel/methylaluminoxane catalyst system

Kinetics of hexene‐1 polymerization was investigated using [(N,N′‐diisopropylbenzene)2,3‐(1,8‐napthly)‐1,4‐diazabutadiene]dibromonickel/methylaluminoxane catalyst. Experiments were performed at varying catalyst and monomer concentrations in the temperature range of ?10 to 35 °C. First order time‐conversion plot shows a downward curvature at temperatures of 20 °C and 35 °C indicating the presence of finite termination reactions. A nonlinear plot of degree of polymerization (P_n) with respect to conversion indicates occurrence of transfer reactions and slow initiation. The experimental molar masses are higher than predicted, which implies that a fraction of catalyst species could not be activated or is deactivated at the early stages of the reactions. The efficiency of the catalyst (Cat_eff) varies from 0.77 to 0.89. The observed polydispersity of the poly(hexene‐1) s is in the range of 1.18–1.48. The reaction order was found to be 1.11 with respect to catalyst. The Arrhenius plot obtained using the overall propagation rate constant, k_p, at five different temperatures (?10, 0, 10, 20, and 35 °C) was found to be linear with an activation energy, E_a = 4.3 kcal/mol. Based on the results presented it is concluded that the polymerization of hexene‐1 under the above‐mentioned conditions shows significant deviation from ideal “living” behavior. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1093–1100, 2007     

Aqueous solution behavior of comb‐shaped poly(2‐ethyl‐2‐oxazoline)

A series of comb polymers consisting of a methacrylate backbone and poly(2‐ethyl‐2‐oxazoline) (PEtOx) side chains was synthesized by a combination of cationic ring‐opening polymerization and reversible addition–fragmentation chain transfer polymerization. Small‐angle neutron scattering (SANS) studies revealed a transition from an ellipsoidal to a cylindrical conformation in D₂O around a backbone degree of polymerization of 30. Comb‐shaped PEtOx has lowered T_g values but a similar elution behavior in liquid chromatography under critical conditions in comparison to its linear analog was observed. The lower critical solution temperature behavior of the polymers was investigated by turbidimetry, dynamic light scattering, transmission electron microscopy, and SANS revealing decreasing T_cp in aqueous solution with increasing molar mass, the presence of very few aggregated structures below T_cp, a contraction of the macromolecules at temperatures 5 °C above T_cp but no severe conformational change of the cylindrical structure. In addition, the phase diagram including cloud point and coexistence curve was developed showing an LCST of 75 °C of the binary mixture poly[oligo(2‐ethyl‐2‐oxazoline)methacrylate]/water. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis of poly(2‐ethylhexyl acrylate)/clay nanocomposite by in situ living radical polymerization

This investigation reports the preparation of tailor‐made poly(2‐ethylhexyl acrylate) (PEHA) prepared via in situ living radical polymerization in the presence of layered silicates and characterization of this polymer/clay nanocomposite. Being a low T_g (?65 °C) material, PEHA has very good film formation property for which it is used in paints, adhesives, and coating applications. 2‐Ethylhexyl acrylate was polymerized at 90 °C using CuBr and Cu(0) as catalyst in combination with N,N,N′,N″,N″‐pentamethyl diethylenetriamine (PMDETA) as ligand. A tremendous enhancement in reaction rate and polymerization data was achieved when acetone was added as additive to increase the efficiency of the catalyst system. PEHA/clay nanocomposite was prepared at 90 °C using CuBr as catalyst in combination with PMDETA as ligand. Different types of clay with same loading were also used to study the effect on reaction rate. The molecular weight (M_n) and polydispersity index of the prepared nanocomposites were characterized by size exclusion chromatography. The active end group of the polymer chain was analyzed by ¹H NMR analysis and by chain extension experiment. Polymer/clay interaction was studied by Fourier Transform Infrared spectrometry and wide‐angle X‐ray diffraction analyses. Distribution of clay in the polymer matrix was studied by the transmission electron microscopy. Thermogravimetric analysis showed that thermal stability of PEHA/clay nanocomposite increases on addition of nanoclay. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Effects of POSS nanoparticles on glass transition temperatures of ultrathin poly(t‐butyl acrylate) films and bulk blends

As a model system, thin films of trisilanolphenyl‐POSS (TPP) and two different number average molar mass (5 and 23 kg mol^?1) poly(t‐butyl acrylate) (PtBA) were prepared as blends by Langmuir–Blodgett film deposition. Films were characterized by ellipsometry. For comparison, bulk blends are prepared by solution casting and the samples are characterized via differential scanning calorimetry. The increase in T_g as a function of TPP content for bulk high and low molar mass samples are in the order of ～10 °C. Whereas bulk T_g shows comparable increases for both molar masses (～10 °C), the increase in surface T_g for higher molar mass PtBA is greater than for low molar mass (～22 °C vs. ～10 °C). Nonetheless, the total enhancement of T_g is complete by the time 20 wt % TPP is added without further benefit at higher nanofiller loads. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 175–182