ATRP Synthesis and Characterization of μ,αω-allyl-terminated Macromonomers as Precursors for End-linked Gels and Hydrogels

2003 ◽  
Vol 774 ◽  
Author(s):  
Lucy Vojtova ◽  
Nicholas J. Turro ◽  
Jeffrey T. Koberstein
Keyword(s):  
Molecular Weight ◽  
Monomer Concentration ◽  
Monomer Conversion ◽  
Catalyst System ◽  
Linear Increase ◽  
Butyl Methacrylate ◽  
First Order Kinetics ◽  
Significant Difference ◽  
Ft Ir

AbstractSynthesis of α,ω-allyl-terminated telechelic macromonomers based on poly(tert-butyl methacrylate) (poly(t-BMA)) and poly(methacrylic acid) (poly(MAA)) was studied with the aim of preparing end-linked gels and hydrogels. Low molecular weight α-allyl-terminated poly(t-BMA) macromonomers with narrow polydispersities (Mw/Mn = 1.16) were synthesized via controlled atom transfer radical polymerization (ATRP) using a Cu(I)Br/N,N,N',N',N',N'-hexamethyltriethylenetetraamine catalyst system in conjunction with an allyl-2-bromoisobutyrate as the functional initiator. The polymerizations exhibited a linear increase of molecular weight in direct proportion to the monomer conversion and first-order kinetics with respect to monomer concentration. No significant difference was found between using polar or non-polar solvents (tetrahydrofuran or benzene, respectively). Optimization of reaction conditions to obtain the highest degree of active terminal bromine is discussed. Quenching the ATRP reaction with allyltributyltin yielded α,ω-allyl-terminated poly(t-BMA) macromonomers by replacing the terminal bromine with ω-allyl functional group. Poly(MAA) macromonomers were prepared by deprotection of the tert-butyl group from α,ω-allyl-terminated poly(t-BMA) macromonomers using concentrated trifluoroacetic acid at room temperature. Successful synthetic steps were confirmed by 1H NMR, FT-IR and MALDI-TOF MS analyses. The α,ω-allyl-terminated macromonomers were proven to be candidates for further polymerization by forming end-linked, non-soluble gels.

Grafting of 2-Diethylaminoethyl Methacrylate onto Silk by ATRP

2011 ◽  
Vol 175-176 ◽  
pp. 614-618 ◽  
Author(s):  
Tie Ling Xing ◽  
Xia Xu ◽  
Guo Qiang Chen
Keyword(s):  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Monomer Concentration ◽  
Catalyst System ◽  
Hydroxyl Groups ◽  
Amino Groups ◽  
E Coli ◽  
Washing Durability ◽  
Ft Ir

In order to develop silk underwear fabric with good anti-bacterial property, silk was grafted using 2-diethylaminoethyl methacrylate (DEAEMA) by atom transfer radical polymerization (ATRP) method. The amino groups and hydroxyl groups on the side chains of the silk fibroin was reacted with 2-bromoisobutyryl bromide (BriB-Br) to obtain efficient macroinitiator for ATRP. And the macroinitiator was grafted with DEAEMA in water/ethanol media using CuBr/N,N,N',N",N" -pentamethyldiethylenetriamine (PMDETA) as catalyst system. The effects of monomer concentration, the proportion of CuBr and PMDETA, grafting temperature and time on the silk grafting were discussed, and the optimal grafting technology was obtained. FT-IR characterization of the grafted silk showed a peak corresponding to DEAEMA, which indicated that DEAEMA was grafted onto the surface of silk. The quaternized grafted silk had good anti-bacterial property to S. aureus and E. coli. . And the bacteria repellency of the grafted silk had good washing durability.

scholarly journals Optimal Control of Non-Isothermal, Batch Polymerization of Methacrylates with Specified Time, Monomer Conversion, and Average Molecular Weights

2021 ◽  
Author(s):  
Baranitharan Sanmuga Sundaram
Keyword(s):  
Molecular Weight ◽  
Optimal Control ◽  
Methyl Methacrylate ◽  
Process Model ◽  
Control Method ◽  
Operation Time ◽  
Monomer Conversion ◽  
Butyl Methacrylate ◽  
Solution Polymerization ◽  
Polymer Molecular Weight

Optimal control policies are determined for the free radical polymerization of three different polymerization processes, in a non-isothermal batch reactor as follows: (1) bulk polymerization of n-butyl methacrylate; (2) solution polymerization of methyl methacrylate with monofunctional initiator; (3) solution polymerization of methyl methacrylate with bifunctional initiator. Four different optimal control objectives are realized for the above three processes. The objectives are: (i) maximization of monomer conversion in a specified operation time, (ii) minimization of operation time for a specified, final monomer conversation, (iii) maximization of monomer conversion for a specified, final number average polymer molecular weight, and (iv) maximization of monomer conversion for a specified, final weight average polymer molecular weight. The realization of these objectives is expected to be very useful for the batch production of polymers. To realize the above four different optimal control objectives, a genetic algorithms-based optimal control method is applied, and the temperature of heat exchange fluid inside reactor jacket is used as a control function. Necessary equations are provided in the above three processes to suitably transform the process model in the range of a specified variable other than time, and to evaluate the elements of Jacobian to help in the accurate solution of the process model. The results of this optimal control application reveal considerable improvements in the performance of the batch polymerization processes.

scholarly journals Molecular Characterization of Arabinoxylan from Wheat Beer, Beer Foam and Defoamed Beer

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1230
Author(s):  
Jie Li ◽  
Jinhua Du
Keyword(s):  
Molecular Weight ◽  
Molecular Characterization ◽  
Average Molecular Weight ◽  
Monosaccharide Composition ◽  
Weight Average Molecular Weight ◽  
Substitution Degree ◽  
Significant Difference ◽  
Spherical Structures ◽  
Beer Foam

This research was to explore the distribution and some molecular characterization of arabinoxylan in wheat beer (B), beer foam (BF) and defoamed beer (DB) because of the crucial influences of arabinoxylan on wheat beer and its foam. The purified arabinoxylan from B, BF, and DB were fractionated by ethanol of 50%, 67%, 75%, and 80%. The monosaccharide composition, substitution degree (Ara/Xyl ratio, A/X), and average degrees of polymerization (avDP) of arabinoxylan were investigated. Molecular weight and microstructure were also involved in this study by GPC-LLS and SEM, respectively. Under the same ethanol concentration, the arabinoxylan content in the BF was higher than the other two, respectively, and it was precipitated in BF fraction with 50% ethanol which accounted for 80.84% of the total polysaccharides. Meanwhile, the greatest substitution degree (A/X) and highest value of avDP of the arabinoxylan was found in all beer foam fractions regardless of the concentration of ethanol used. The average degrees of polymerization (avDP) of arabinoxylan displayed a significant difference (p < 0.05) among B, BF, and DB. Furthermore, arabinoxylan presented varied microstructure with irregular lamellas and spherical structures and the weight-average molecular weight (Mw) of arabinoxylan showed the lowest values in BF, while the largest values were shown in DB. Therefore, arabinoxylan was more accumulated in beer foam, especially in 50% ethanol, characterised by greater value of A/X and avDP, as well as lower Mw. It was suggested that the arabinoxylan played important roles in maintaining wheat beer foam characteristics.

scholarly journals A Complexed Initiating System AlCl3·Phenetole/TiCl4·H2O with Dominant Synergistic Effect for Efficient Synthesis of High Molecular Weight Polyisobutylene

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2121
Author(s):  
Yulong Jin ◽  
Liang Chen ◽  
Xing Guo ◽  
Linfeng Xu ◽  
Zhihua Zhu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Synergistic Effect ◽  
High Molecular Weight ◽  
Monomer Concentration ◽  
Catalyst System ◽  
Polymerization Temperature ◽  
Simple Preparation ◽  
Order Of Magnitude ◽  
Unique Approach ◽  
High Molecular Weight Polyisobutylene

A complexed initiating system AlCl3·phenetole/TiCl4·H2O was prepared by simply compounding AlCl3/phenetole and TiCl4/H2O and used for cationic polymerization of isobutylene. It was found AlCl3·phenetole/TiCl4·H2O exhibited activities 1.2–3 times higher than those of AlCl3/phenetole, and more than an order of magnitude higher than those of TiCl4/H2O, which indicated a notable synergistic effect produced in the complexed system. In addition, due to the higher activity of AlCl3·phenetole/TiCl4·H2O, lower coinitiator concentration and polymerization temperature, as well as higher monomer concentration were more favored for this complexed initiating system to produce polyisobutylene (PIB) with reasonable molecular weight (Mw) and molecular weight distribution (MWD). Furthermore, high molecular weight polyisobutylene (HPIB) with Mw = 1–3 × 105 g·mol−1 could be successfully produced by the complexed catalyst system at Tp = −60 to −40 °C. As a whole, the high activity as well as the simple preparation procedures of the complexed initiating system offer us a unique approach for the production of HPIB with improved efficiency.

Surface Grafting Modification of Silk Fibroin by Atom Transfer Radical Polymerization

2008 ◽  
Vol 373-374 ◽  
pp. 629-632 ◽  
Author(s):  
Tie Ling Xing ◽  
Hai Jiang Wang ◽  
Zhan Xiong Li ◽  
Guo Qiang Chen
Keyword(s):  
Silk Fibroin ◽  
Gel Permeation Chromatography ◽  
Catalyst System ◽  
Hydroxyl Groups ◽  
Amino Groups ◽  
Grafting Modification ◽  
Antibacterial Surface ◽  
Ft Ir ◽  
Tertiary Amino

In this work, surface modification of silk fibroin was conducted by grafting dimethylaminoethyl methacrylate (DMAEMA) via ATRP to produce well controlled grafting silk. First, the amino groups and hydroxyl groups on the side chains of the silk fibroin reacted with 2-bromoisobutyryl bromide (BriB-Br) to obtain efficient initiator for ATRP. Subsequently, the functional silk fibroin was used as macroinitiator of DMAEMA in 1,2-dichlorobenzene in conjunction with CuBr/N,N,N',N",N" -pentamethyldiethylenetriamine (PMDETA) as a catalyst system. FT-IR characterization of the modified silk substrate showed a peak corresponding to DMAEMA indicating that the polymer had been formed on the silk surface. Following the polymerization, the tertiary amino groups on the grafted silk fibroin were quaternized to produce a large concentration of quaternary ammonium groups, which endowed the silk substrate with potential antibacterial surface. The graft chains were cleaved by acid hydrolysis and analyzed by gel permeation chromatography (GPC). The GPC results indicated that the graft layer were well-controlled.

scholarly journals Extraction and Characterization of Sugarcane Peel Wax

ISRN Agronomy ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Mangesh B. Inarkar ◽  
S. S. Lele
Keyword(s):  
Fatty Acids ◽  
Molecular Weight ◽  
Gas Chromatography ◽  
Fourier Transform ◽  
Dry Weight ◽  
Weight Basis ◽  
Ft Ir ◽  
Gas Chromatography Mass Spectroscopy ◽  
Layer Chromatography

Sugarcane peel is an agrowaste product and contains considerable amount of wax. This has a good technoeconomic potential. In view of this, the present study aims at extraction and characterization of wax from sugarcane peel. The yield of crude wax was 0.95% on dry weight basis. During Fourier transform-infrared spectroscopy (FT-IR) prominent peaks obtained at 2921.73 and 2851.64 (–CH), 1463.44 (–CH2), 1376.96 (–CH3), 1108.4 and 1170.16 (–C–O) 3395.60 (–OH), 1710.25 (–CHO), and 1736.63 (–COOH) indicate presence of alkanes, ketones, alcohols, aldehydes, and carboxylic acids, respectively. Alcohol and hydrocarbon fractions were also found by thin layer chromatography (TLC). Melting point of crude wax was observed to be 62.1°C. Molecular weight of wax was estimated to be 1706 Dalton. Composition of crude wax found using gas chromatography-mass spectroscopy (GC-MS) was alkanes (28.83%), ester (66.26%), fatty acids (4.58%), aldehyde (0.11%), and alcohol (0.22%).

Determination of Molecular Weight and Structure Characterization of Canna Amylose Purified Using the Method of n-Butanol Recrystallization

2012 ◽  
Vol 554-556 ◽  
pp. 1216-1222
Author(s):  
Hai Xin Shi ◽  
Yan Zhen Yin ◽  
Xiao Xi Hu ◽  
Shu Fei Jiao
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Structure Characterization ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Granule Surface ◽  
Chemical Groups ◽  
Ubbelohde Viscometer

The canna amylose (CAM) was separated from canna starch grown in China and purified both using the method of n-butanol recrystallization. The purity, morphology, spectral properties and molecular weight of CAM were characterized by ultraviolet and visible spectrophotometer (UV/Vis), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscope (FT-IR) and Ubbelohde viscometer. Maximum absorption wavelength of the purified CAM (635－638 nm) and it’s blue values (BV) (1.167 ± 0.209) prove that the purification of the CAM by n-butanol recrystallization was successfully carried out. The SEM results show that CAM granule surface become rougher and the CAM granule size become smaller than that of canna starch. The XRD results suggest that most of CAM granule is amorphous. And the FT-IR results show that the basic chemical groups of canna starch are also presented in CAM. However, the amorphous area of CAM is increased. The intrinsic viscosity and viscosity-average molecular weight of CAM is 78.5 mL/g and 1.65×105, respectively.

scholarly journals SYNTHESIS AND CHARACTERIZATION OF ACETYLATION OF SUPRA MOLECULAR DENDRIMERS

2021 ◽  
Vol 10 (4) ◽  
pp. 3430-3434
Author(s):  
Hemant Khambete
Keyword(s):  
Molecular Weight ◽  
Size Distribution ◽  
Blood Cells ◽  
Mass Spectra ◽  
Synthesis And Characterization ◽  
Time Duration ◽  
Standard Data ◽  
Ft Ir ◽  
Hemolytic Toxicity

Supra molecular dendrimers have emerged as one of the most interesting themes for researchers work as a result of unique functional architecture and macromolecular characteristics. The main drawback of Supra Molecular dendrimers is, due to presence of –NH2 group at the surface, it causes hemolytic toxicity and hence toxic for the blood cells. In this article, we have systematically modified the surface groups of amine-terminated Supra Molecular dendrimers with acetyl groups. The reported methods of Acetylation are very time consuming and multistep which require large amounts of chemicals. In present work we have synthesized Acetylation Supra Molecular dendrimers using 1-ethyl 3- [3-(dimethylamino) propyl] carbodiimide (EDC) as a cross linking agent. The Acetylated dendrimers were evaluated by color reaction, UV, FT-IR, DSC, Size distribution, NMR and ESI Mass Spectra studies and compared with standard data. The absolute molecular weight and molecular weight distribution of 4.0 G and Acetylated Supra Molecular dendrimers were determined respectively by Size distribution and ESI Mass Spectra respectivel. The results revealed that our approach for Acetylation gives considerable amount of Acetylation, cheap, elimination for ganic solvent, requires less time duration and hence gives a better option for Acetylation of dendrimers.

Synthesis of Liquid Polyisoprene with High cis-1,4 Unit Content and Narrow Molecular Weight Distribution Using Neodymium Phosphate Catalyst

2019 ◽  
Vol 72 (6) ◽  
pp. 467 ◽  
Author(s):  
Jie Liu ◽  
Xin Min ◽  
Xiuzhong Zhu ◽  
Zichao Wang ◽  
Tong Wang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Catalyst System ◽  
Size Exclusion ◽  
Narrow Molecular Weight Distribution ◽  
13C Nmr Analysis ◽  
Exclusion Chromatography ◽  
Ft Ir ◽  
Ternary Catalyst

The polymerization of isoprene (Ip) initiated by a ternary catalytic system consisting of liquid Nd(P204)3 (Nd), Al(i-Bu)2H (Al), and CHCl3 (Cl) in cyclohexane was examined. The effects of order of addition and amount of Ip, Al, and Cl in the catalyst on the polymerization were evaluated. The molecular weight (Mn), molecular weight distribution (Mw/Mn), and microstructure of the polymer were characterized using size exclusion chromatography and multiangle light scattering, FT-IR, 1H NMR and 13C NMR analysis. The results indicate that the order of addition, i.e. Nd+Ip+Al+Cl and ratios of [Ip]/[Nd]=30, [Al]/[Nd]=20, and [Cl]/[Nd]=3 were essential for the optimized ternary catalyst system Nd(P204)3/Al(i-Bu)2H/CHCl3. The resulting liquid polyisoprene (LIR) has a high cis-1,4 unit content (&gt;98%) and a narrow molecular weight distribution (Mw/Mn&lt;1.2). The molecular weight of the polymer was precisely controlled.

Living free radical polymerization of styrene with 2-cyanoprop-2-yl dithionaphthalate as RAFT agent

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Zhu Jian ◽  
Zhu Xiulin ◽  
Zhou Di ◽  
Chen Jianying
Keyword(s):  
Molecular Weight ◽  
Reaction Temperature ◽  
Raft Polymerization ◽  
Monomer Concentration ◽  
Gel Permeation Chromatography ◽  
Monomer Conversion ◽  
Bulk Polymerization ◽  
Polymerization Rate ◽  
Chain Extension ◽  
Raft Agent

Abstract The reversible addition-fragmentation chain transfer (RAFT) bulk polymerization of styrene was studied using 2-cyanoprop-2-yl dithionaphthalate (CPDN) as RAFT agent in the presence or absence of 2,2’-azoisobutyronitrile (AIBN). The results of both thermally and AIBN-initiated styrene (St) polymerizations show that St can be polymerized in a controlled way using CPDN as RAFT agent; i.e., the polymerization rate is first order with respect to monomer concentration, and molecular weight increases linearly with monomer conversion. The molecular weights obtained from gel permeation chromatography are close to the theoretical values and molecular weight distributions are relatively narrow (Mw/Mn < 1.2). It is confirmed by chain extension reaction that the polymer prepared via RAFT polymerization can be used as a macroRAFT agent. The effects of reaction temperature and mole ratios [St]0/[CPDN]0/[AIBN]0 on the polymerization were investigated. The results indicate that the reaction temperature has a positive effect on the polymerization rate, but little effect on molecular weight and molecular weight distribution, and the optimum mole ratios were found to be [CPDN]0/[AIBN]0 > 4/3 and [St]0/[CPDN]0 < 800.

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