Molecular Weight Poly Research Articles

Colorimetric detection of poly(methyl methacrylate) using polydiacetylene/zinc(II)/zinc oxide nanocomposites

This study introduces a facile approach for fabricating colorimetric sensors that differentiate concentration and molecular weight of poly(methyl methacrylate) (PMMA). A cationic surfactant, cetyltrimethylammonium bromide (CTAB), is incorporated into the structure of polydiacetylene(PDA)/Zn2+/ZnO nanocomposites via a simple mixing process. The interaction between PMMA carbonyl group and CTAB headgroup is the key mechanism inducing color transition of the nanocomposites. The sensitivity can be tuned by adjusting experimental parameters including CTAB concentration, photopolymerization time, and PDA alkyl chain length. Solid-state sensors are fabricated by embedding into filter papers. Our finding extends the utilization of PDA-based materials in polymer sensing applications.

One-Pot Preparation of Metal-Polymer Nanocomposites in Irradiated Aqueous Solutions of 1-Vinyl-1,2,4-triazole and Silver Ions.

Metal–polymer nanocomposite polyvinyltriazole–silver nanoparticles were obtained using one-pot synthesis in irradiated aqueous solutions of 1-vinyl-1,2,4-triazole (VT) and silver ions. Gel permeation chromatography data show that upon radiation initiation, the molecular weight of poly(1-vinyl-1,2,4-triazole) increases with increasing monomer concentration. To study the kinetics of polymerization and the features of the radiation–chemical formation of nanoparticles, UV-Vis spectroscopy was used. TEM images show a relatively small average size of the forming nanoparticles (2–3 nm) and a narrow size distribution, which shows the effective stabilization of nanoparticles by triazole substituents at a molar ratio of VT and silver ions of 25/1. The addition of ethyl alcohol was used to increase the efficiency of synthesis and suppress the crosslinking of macromolecules in solution. The results of the work show that aqueous–alcoholic solutions of 1 wt.% VT can be used to obtain soluble nanocomposite materials. 10 wt.% monomer solutions have prospects for use in the preparation of polymer gels filled with nanoparticles.

More Precise Control of the In Vitro Enzymatic Degradation via Ternary Self-Blending of High/Medium/Low Molecular Weight Poly(trimethylene carbonate)

To more precisely control the degradation rate of poly(trimethylene carbonate) (PTMC), self-blending films were prepared via the ternary self-blending of pure PTMC with a molecular weight of 334, 152, and 57 kg/mol. The in vitro enzymolysis degradation of the ternary self-blending films was performed in lipase solutions. The results showed that ternary self-blending could control the degradation of PTMC by adjusting the mass ratio of high/medium/low molecular weight PTMC in the composition, and the PTMC334/PTMC152/PTMC57 films with a mass ratio of 1/4/16 showed mass loss of 85.96% after seven weeks of degradation, while that of PTMC334/PTMC152/PTMC57 films with a mass ratio of 1/1/1 was 96.39%. The former and latter’s degradation rate constant was 13.263 and 23.981%/w, respectively, and the former presented better morphology stability than the latter. The strategy of ternary self-blending could simultaneously bestow PTMC with a lower degradation rate and good morphology stability, indicating that ternary self-blending is an efficient way to control the degradation performance of PTMC more precisely.

Effect of multi-functional epoxy chain extender on the weathering resistance performance of Poly(butylene adipate-co-terephthalate) (PBAT)

In this research work, both natural weathering and artificial weathering processes were carried out to investigate the effects of multi-functional epoxy chain extender (Joncryl ADR 4370) content on the degradation and the mechanical properties and molecular weight of poly(butylene adipate-co-terephthalate) (PBAT). The carboxyl end-groups of PBAT decreased significantly with an increase in ADR content from 0 to 1.5 wt%. Similarly, the molecular weight of PBAT initially increased and then decreased because of the formation of a crosslinked network structure under the influence of excessive chain extenders. The main degradation mechanism of PBAT during the natural and artificial weathering process is photo-degradation and hydrolyzation. The degradation rate of PBAT increased with increasing content of chain extender, as hydroxyl groups facilitate the water attack on the ester bonds of PBAT. In contrast, the higher content of chain extender presented the lower loss velocity of the tensile strength. This is mainly because the more ADR content, the more crosslinking network structures will be formed during the melting extrusion which can slow down the decrease of tensile strength. Hence, it is indicated that the crosslinking structure has more effect on tensile strength than that of hydrolysis effect during degradation. According to the analysis and study on the performance changes of PBAT/ADR materials under the conditions of long-term natural weathering (360d) and artificial weathering (600 h), this work provides theoretical guidance to produce PBAT mulching films with excellent performance.

Effect of glycolide dosage on molecular weight of poly (lactic-co-glycolic acid)

A series of biodegradable polymers, poly (lactic-co-glycolic acid) (PLGA) were prepared by ring-opening polymerization with racemic lactide and glycolide as main raw materials. Gel Permeation Chromatography (GPC), differential scanning calorimetry (DSC) and ubbelohde viscometer were uesd for the characterizations of the PLGA. And the effect of glycolide’s (GA) content on molecular weight (Mw), vitrification transition temperature (Tg), intrinsic viscosity [η] of PLGA was discussed. The results show that the GA’s content in PLGA molecular structure is higher than the actual feeding ratio. Meanwhile, with the increase of GA’s content, the Mw, [η] and Tg of PLGA decreased.

Kinetics of D,L-Lactide Polymerization Initiated with Zirconium Acetylacetonate.

The kinetic of D,L‐lactide polymerization in presence of biocompatible zirconium acetylacetonate initiator was studied by differential scanning calorimetry in isothermal mode at various temperatures and initiator concentrations. The enthalpy of D,L‐lactide polymerization measured directly in DSC cell was found to be ΔH=−17.8±1.4 kJ mol−1. Kinetic curves of D,L‐lactide polymerization and propagation rate constants were determined for polymerization with zirconium acetylacetonate at concentrations of 250–1000 ppm and temperature of 160–220 °C. Using model or reversible polymerization the following kinetic and thermodynamic parameters were calculated: activation energy Ea=44.51±5.35 kJ mol−1, preexponential constant lnA=15.47±1.38, entropy of polymerization ΔS=−25.14 J mol−1 K−1. The effect of reaction conditions on the molecular weight of poly(D,L‐lactide) was shown.

FTIR spectroscopic study of enthalpy differences of conformers of substituted ethanes in PVB plasticized by PEGs

In present investigation, the enthalpy differences of conformers for substituted ethanes in PVB/PEG 200, PVB/PEG 400 and PVB/PEG600 blended systems with the compositions of 80:20, 70:30, 60:40 and 50:50 have been determined by FTIR spectroscopy. The influence of the plasticizer content and molecular weight of poly(ethylene glycol) on the enthalpy difference of the conformers has been studied.

Effect of the Molecular Structure and Molecular Weight of Poly(Vinylidene Fluoride-Chlorotrifluoroethylene) Copolymers on the Characteristic Properties of TATB-based Composites

Effect of the Molecular Structure and Molecular Weight of Poly(Vinylidene Fluoride-Chlorotrifluoroethylene) Copolymers on the Characteristic Properties of TATB-based Composites

Effect of pgsE expression on the molecular weight of poly(γ-glutamic acid) in fermentative production

Poly(γ-glutamic acid) (PGA) is a biopolymer produced by Bacillus spp. via the γ-amide linkages of d- and/or l-glutamate. Although high-molecular-weight (HMW) PGA possesses many attractive properties, such as flocculating, wound healing, and immune-stimulating effects, no studies have reported factors useful for increasing the molecular weight of PGA during microbial production. PgsB, PgsC, and PgsA are the minimum protein sets required for PGA production in B. subtilis, and PgsE improves PGA productivity. Analysis by size-exclusion chromatography combined with multiangle laser light scattering revealed that the molecular weight of PGA was Mw = 2,900,000 g mol−1 and predominantly Mw = 47,000 g mol−1 in preparations derived from B. subtilis cells with and without pgsE, respectively. PgsE may be required to increase the molecular weight of PGA. Poly(γ-glutamic acid) (PGA) is a biopolymer produced by Bacillus spp. via the γ-amide linkages of d- and/or l-glutamate. PgsB, PgsC, and PgsA are the minimum protein set required for PGA production in B. subtilis, and PgsE improves PGA productivity. Analysis by size-exclusion chromatography combined with multiangle laser light scattering revealed that the molecular weight of PGA was Mw = 2,900,000 g mol−1 or predominantly Mw = 47,000 g mol−1 in preparations derived from B. subtilis cells with or without pgsE, respectively. PgsE may be required to increase the apparent molecular weight of PGA.

Investigation of molecular weight effect on lignin flocculation induced by poly(diallyldimethylammonium chloride) (PDADMAC) through population balance modeling

In this research, population balance model was employed to investigated the effect of different molecular weights of poly(diallyldimethylammonium chloride) (PDADMAC) on flocculation process for lignin recovery. Results shows high molecular weight PDADMAC (1,100,000 g/mol) resulted in higher collision efficiency, higher restructure rate and stronger flocs than the lower molecular weight PDADMAC (200,000 g/mol). High molecular weight PDADMAC (1,100,000 g/mol) facilitated bridging while low molecular weight PDADMAC (200,000 g/mol) induced electrostatic patch flocculation mechanism. Polymer dosage, shear rate, temperature and electrolyte concentration affected both flocculation systems to different extents. Shear rate had more significant effect on the high molecular weight PDADMAC (1,100,000 g/mol) flocculation system than on low molecular weight PDADMAC (200,000 g/mol) flocculation system. The addition of a electrolyte had positive effect on the collision efficiency but negative effect on floc strength. More significant restructure at higher ionic strength was also observed.

Polyethersulfone microfiltration membrane modified by an amphiphilic dithiolane‐containing copolymer for improving anti‐protein‐fouling performance and rejection of nanoparticles

To endow polyethersulfone (PES) membranes with enhanced hydrophilicity and anti‐protein adsorption performance, amphiphilic dithiolane‐containing copolymers poly[poly(ethyleneglycol)methylethermethacrylate‐co‐2‐(methacryloyloxy)ethyl 5‐(1,2‐dithiolan‐3‐yl)pentanoate‐co‐(4‐formylphenyl)‐2‐methylprop‐2‐enoate]{abbr. Poly(MAPEG‐co‐MALA‐co‐MAHA)} with different polymerization degree were successfully synthesized, and then blended with PES to prepare microfiltration membranes by immersion precipitation phase inversion process. The chemical structure and molecular weight of poly(MAPEG‐co‐MALA‐co‐MAHA) were characterized by NMR, FTIR and GPC. The morphology and surface property of the as‐prepared blending membranes were also characterized by SEM, AFM and contact angle testing etc. Compared with pure PES membrane, the contact angle of PES/poly(MAPEG‐co‐MALA‐co‐MAHA) membranes decreased from 74.2° to 53.7°, and the bovine serum albumin (BSA) adsorption declined from 121.4 to 58.8 μg cm−2. Meantime, the water flux of PES/poly(MAPEG‐co‐MALA‐co‐MAHA) membranes increased from 38.6 to 89.1 L m−2 h−1, the flux recovery ratio increased from 68.3% to 93.3% and the irreversible flux decline ratio decreased from 31.7% to 6.7%. Furthermore, the mechanical property of PES/poly(MAPEG‐co‐MALA‐co‐MAHA) membrane was better than that of pure PES membrane. In addition, the rejection of BSA and Au nanoparticle reached 77.3% and 66.2% respectively. The results showed that the addition of poly(MAPEG18‐co‐MALA18‐co‐MAHA18) with tiny amount could not only improve the hydrophilicity and antifouling of the membrane, but also endow the microfiltration membrane with the rejection of nanoparticles.

Synthesis of Soluble Novel Polyacetylenes Containing Carbamate and Eugenol Moieties

This study was aimed to synthesize a series of novel polyacetylenes containing carbamate and eugenol moieties. The polymerization of 1-(3,4-dimethoxyphenyl) propane-2-yl prop-2-ynylcarbamate (1), 1-(3,4-dimethoxyphenyl)propane-2-yl 3-ethynyl phenylcarbamate (2), 1-(3,4-dimethoxyphenyl)propane-2-yl 4-ethynylphenylcarbamate (3), (2S)-1-(3,4-dimethoxyphenyl)propane-2-yl 2-((prop-2ynyloxy)carbonylamino)propanoate (4) in the presence of (nbd)Rh+[ɳ6-C6H5B–(C6H5)3] as catalyst have successfully produced corresponding polyacetylenes [poly(1)–poly(4)] in high yield. The molecular weight of the synthesized polyacetylenes ranged between 13,900–18,400 g/mol. In particular, the molecular weight of poly(1) could be increased by the addition of menthol. Practically, these polymers were found to have a stable helical structure and soluble in common organic solvents.

Lipase-catalyzed synthesis and post-polymerization modification of new fully bio-based poly(hexamethylene γ-ketopimelate) and poly(hexamethylene γ-ketopimelate-co-hexamethylene adipate) copolyesters

Abstract A novel full bio-based ketone-containing aliphatic polyester was prepared by enzyme-catalyzed polycondensation of diethyl γ-ketopimelate (DEK) with 1,6-hexanediol (HDO) using immobilized lipase B from Candida antarctica (CALB). The influences of polymerization conditions such as temperature, time, enzyme amount, and solvent amount on the molecular weight of poly(hexamethylene γ-ketopimelate) (PHK) were investigated. New fully bio-based poly(hexamethylene γ-ketopimelate-co-hexamethylene adipate) (poly(HK-co-HA)) copolymers with narrow polydispersity and well-defined composition were synthesized by copolymerization of DEK, HDO, and diethyl adipate. The structures of PHK and poly(HK-co-HA) copolymers were characterized by nuclear magnetic resonance, and their thermal characterization was examined by thermogravimetric analysis and differential scanning calorimetry. The degradation of PHK and poly(HK-co-HA) copolymers was studied. The post-polymerization modification of these polyketoesters via oxime click chemistry was further demonstrated.

Mussel‐Inspired Surface Acrylation on Graphene Oxide Using Acrylic Surface Primers and Its Hydrogel‐Based Applications: Sustained Drug Release and Tissue Scaffolds

AbstractComposite hydrogels integrated with graphene oxide were prepared to enable the sustained release of loads for graphene‐based aromatic drug delivery and enhanced cell adhesion for tissue scaffolds. The surface of graphene oxide was readily transformed by the adsorption of acrylic surface primer (SP) without chemical reactions. The surface modification was verified by energy dispersive X‐ray spectroscopy and X‐ray diffraction spectra. The acrylated graphene oxide (SP‐GO) was photocrosslinked with acrylate groups of poly(ethylene glycol) to generate a composite hydrogel (SP‐GO hydrogel). Based on the molecular weight of poly(ethylene glycol), the hydrogels showed a swelling ratio range of ∼5–20, respectively. The SP‐GO did not change noticeably mechanical properties and inner structures of the hydrogels. Aromatic doxorubicin (DOX) was entrapped in the hydrogels with good yield and demonstrates the potential for a drug delivery carrier. The released DOX from the hydrogel containing SP‐GO (70.56% of entrapped DOX) exhibited a sustained release profile with reduced release after five days in a wet environment compared to the released DOX from a hydrogel without SP‐GO (92.29% of entrapped DOX). DOX is supposed to be attracted to graphene oxide and is physically entrapped inside the hydrogels. Moreover, bone MG‐63 cells entrapped in the SP‐GO hydrogel showed increased TGF‐β and fibronectin expression levels. This implies that SP‐GO contributes to enhancing cell growth and adhesion by providing cell‐laid structural support.

Synthesis of new imidazole-based monomer and copolymerization studies with methyl methacrylate

In this study, copolymers were synthesized using methyl methacrylate (MMA) and 2-allyloxymethyl-1-methylimidazole (AOMMI) monomers at various ratios. For this purpose, hydroxyl end-functionalized imidazole was initially prepared with 1-methylimidazole and then it was used to prepare allyl-derived imidazole monomers. Finally, the synthesis of copolymers (poly(MMA-co-AOMMI)) was carried out using different proportions of commercial MMA and AOMMI monomers. Photopolymerization method was preferred as polymerization technique. The polymerization was carried out in solvent-free medium and benzophenone was used as the initiator. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR) and elemental analysis were used for the structural characterization of the obtained copolymers. Molecular weights and the thermal behaviour of the synthesized copolymers were analysed with gel permeation chromatography (GPC) and thermogravimetry (TG) techniques, respectively. The surface of the products was tried to be illuminated using scanning electron microscopy (SEM). According to the obtained FTIR, NMR and elemental analysis results, the copolymers were successfully synthesized. A number average molecular weights of poly(MMA-co-AOMMI) samples were found 13,500 (MMA:2/AOMMI:1), 16,600 (MMA:1/AOMMI:2) and 17,300 (MMA:1/AOMMI:1) according to the mixing ratios. When the thermal stabilities of the synthesized copolymers were observed, it has been seen that those containing imidazole had higher stability than the neat PMMA.

Poly(ester imide)s Possessing Low Coefficients of Thermal Expansion and Low Water Absorption (V). Effects of Ester-linked Diamines with Different Lengths and Substituents.

A series of ester-linked diamines, with different lengths and substituents, was synthesized to obtain poly(ester imide)s (PEsIs) having improved properties. A substituent-free ester-linked diamine (AB-HQ) was poorly soluble in N-methyl-2-pyrrolidone at room temperature, which forced the need for polyaddition by adding tetracarboxylic dianhydride solid into a hot diamine solution. This procedure enabled the smooth progress of polymerization, however, accompanied by a significant decrease in the molecular weights of poly(amic acid)s (PAAs), particularly when using hydrolytically less stable pyromellitic dianhydride. On the other hand, the incorporation of various substituents (–CH3, –OCH3, and phenyl groups) to AB-HQ was highly effective in improving diamine solubility, which enabled the application of the simple polymerization process without the initial heating of the diamine solutions, and led to PAAs with sufficiently high molecular weights. The introduction of bulkier phenyl substituent tends to increase the coefficients of thermal expansion (CTE) of the PEsI films, in contrast to that of the small substituents (–CH3, –OCH3). The effects of ester-linked diamines, consisting of longitudinally further extended structures, were also investigated. However, this approach was unsuccessful due to the solubility problems of these diamines. Consequently, the CTE values of the PEsIs, obtained using longitudinally further extended diamines, were not as low as we had expected initially. The effects of substituent bulkiness on the target properties, and the dominant factors for water uptake (WA) and the coefficients of hygroscopic expansion (CHE), are also discussed in this study. The PEsI derived from methoxy-sustituted AB-HQ analog and 3,3′,4,4′-biphenyltetracarboxylic dianhydride achieved well-balanced properties, i.e., a very high Tg (424 °C), a very low CTE (5.6 ppm K−1), a low WA (0.41%), a very low CHE value (3.1 ppm/RH%), and sufficient ductility, although the 26 μm-thick film narrowly missed certification of the V-0 standard in the UL-94V test. This PEsI film also displayed a moderate εr (3.18) and a low tan δ (3.14 × 10−3) at 10 GHz under 50% RH and at 23 °C. Thus, this PEsI system is a promising candidate as a novel dielectric substrate material for use in the next generation of high-performance flexible printed circuit boards operating at higher frequencies (≥10 GHz).

Effect of molecular weight of poly(ethylene glycol) as humectant in interpenetrating polymer network hydrogels based on poly(sodium AMPS) and gelatin for wound dressing applications

Hydrogel composed of poly(sodium 2-acrylamido-2-methylpropane sulfonate) and gelatin containing different molecular weights of poly(ethylene glycol) (PEG) as a humectant were prepared via UV photopolymerization. The results indicated that the PEG slowed down evaporative water loss and water vapor transmission. Water transport, whether it was absorption, transmission or evaporation, and also tensile properties were found to be dependent to varying extents on the PEG molecular weight. These results could also be related to the amount of non-freezable water, as determined by differential scanning calorimetry. These properties and their relevance to the hydrogel’s potential use as a wound dressing are discussed.

Synthetic scheme to improve the solid content of biodegradable waterborne polyurethane by changing the association relationships of hydrophilic fragments.

A synthetic method was developed to prepare biodegradable waterborne polyurethanes (BHPUs) with a high solid content by introducing different molecular weights of poly(ethylene glycol) (PEG) into poly(ε-caprolactone) (PCL)-based polyurethanes. PCL is a semi-crystalline polymer that can be degraded in lipase to prepare biodegradable waterborne polyurethanes. The biodegradability of BHPUs was evaluated, and the results showed that BHPU samples could be degraded in a solution of phosphate-buffered saline (PBS)/lipase but not in PBS. Two different synthesis routes were used to prepare the BHPUs, which resulted in different association relationships between the ionic hydrophilic polymer dimethylol propionic acid (DMPA) and a nonionic hydrophilic polymer (PEG). The influence of the association relationship between DMPA and PEG on the solid content and other BHPU properties was investigated. The results showed that the method of associating all PEG molecules with DMPA increased the crystallization, tensile properties, and water and soil repellency of the BHPU samples. The solid content of the BHPU samples increased from 41% to 52.7%. In addition, PEG with molecular weights of 400 g mol−1 and 1000 g mol−1 had the best effect on the dispersibility and stability of BHPU samples when incorporated into a polyurethane backbone.

Non-Isothermal and Isothermal Crystallization Behavior of Polylactic/Poly(D-lactic) Blends with Various Molecular Weights of Poly(D-lactic) Acid

Non-isothermal and isothermal crystallization of polylactic acid/poly(D-lactic) acid blends with various molecular weights have been investigated. Formation of polylactic acid stereocomplex crystal between L-lactic acid segments and D-lactic acid segments in the blends was confirmed by the differential scanning calorimetry and X-ray diffraction. The non-isothermal crystallization kinetics of polylactic acid and the blends was studied and analyzed by Kissinger equation. The crystallization temperature was found to depend on the content and molecular weight of poly(D-lactic) acid. Higher content and lower molecular weight of poly(D-lactic) acid have a more pronounced effect on improving crystallization temperature of the blends and effectively reduce the crystallization activation energy of the blends. Isothermal crystallization kinetics of polylactic acid and the blends was also investigated at various temperatures and analyzed by Avrami equation.

Rheological Properties of Poly(acrylic acid) Complexes with Poly(sodium styrenesulfonate) in Semidilute Aqueous Solutions

Solutions of poly(acrylic acid) mixtures with poly(sodium styrenesulfonate) in water and in decimolar hydrochloric acid are studied by potentiometry, viscometry, and rotational rheometry. It is shown that, in a wide range of mixture compositions, thermosensitive polyelectrolyte complexes are formed via ion–dipole interactions of functional groups of polymers. The formation of complexes in the semidilute solution regime is accompanied by a significant increase in viscosity as compared with solutions of the initial polymers, which makes it possible to obtain systems with high viscosity without using large concentrations of polyelectrolytes. The dependence of viscosity on the composition of the mixture passes through a maximum corresponding to the most complete binding of the components of the complex, and the position of the maximum does not depend on the molecular weight of poly(sodium styrenesulfonate) and is determined by the ratio of the concentrations of the functional groups of the polymers. The frequency dependences of the storage modulus and the loss modulus demonstrate that the system experiences strong structuring in the process of complex formation.