Day 1 :
Keynote Forum
Dusan Berek
Polymer Institute of the Slovak Academy of Science, Slovakia
Keynote: Separation of parent homopolymers from diblock copolymers by liquid chromatography under limiting conditions of desorption. Block copolymers with highly adsorptive blocks
Time : 09:30-10:05
Biography:
Abstract:
Synthetic block copolymers represent an important group of advanced materials with numerous specific applications. Polymer chains with different chemical or physical characteristics are bonded together in the block copolymers to obtain required properties. Most block copolymers however, contain free, non-attached chains, their parent homopolymers, which form expensive ballast. The separation and molecular characterization of parent homopolymers from the block copolymers is an analytical challenge. The selectivity of exclusion based gel permeation chromatography, which is commonly applied for separation of macromolecules according to their size, usually does not enable separation of parent homopolymers from the block copolymers. Coupled liquid chromatography methods, CLC that combine exclusion with interaction separation mechanisms may solve the problem. A novel, high selectivity CLC approach is liquid chromatography under limiting conditions of desorption, LC LCD. LC LCD column is packed with polar, porous, adsorptive material. Eluent suppresses sample adsorption. The multicomponent polymers are separated due to the action of a zone of appropriate liquid barrier injected into a column before sample solution. The molecules of the barrier permeate the packing pores and elute slowly, while the pore-excluded macromolecules tend to proceed fast. The barrier promotes adsorption of interactive polymer chains within the column and decelerates their elution. Then non-interactive chains elute freely. As result, macromolecules with distinct polarities are efficiently separated based on the difference in their adsorptivity. Numerous parent homopolymers were separated from their block copolymers with help of LC LCD. However, high polarity polymer chains such as poly(4-vinyl pyridine) and poly(N-vinyl pyrrolidone) are fully retained within common bare silica gel column packing’s even using the strongest desorbing eluents available. To solve the problem, various less polar adsorptive column packing’s were tested. We will show that silica gel with bonded poly(ethylene oxide) chains enables to efficiently separate above parent homopolymers from their block copolymers.
Recent Publications
- Berek D (2017) Separation of parent homopolymers from nonpolar block copolymers by means of liquid chromatography under limiting conditions of enthalpic interactions. Macromolecular Chemistry Physics 218:137-142.
- Berek D (2016) Critical assessment of “critical” liquid chromatography of block copolymers (2016) Journal of Separation Science 39(1):93–101.
- Berek Dand Macova E (2015) Liquid chromatography under limiting conditions of desorption 6: Separation of a four-component polymer blend. Journal of Separation Science 38(4):543-549.
- Rollet M, Pelletier B, Altounian A, Berek D and Maria S (2014) Separation of Parent Homopolymers from Polystyrene-b-poly(ethylene oxide)-b-polystyrene Triblock Copolymers by Means of Liquid Chromatography: 1. Comparison of Different Methods, Analytical Chemistry 86:2694−2702.
- Šiskova A, Macova E and Berek D (2012) Liquid chromatography under limiting conditions of desorption 4: Separation of blends containing low-solubility polymers. European Polymer Journal 48(1):155-168.
- Major Chromatographic Techniques
Location: Dublin, Ireland
Chair
Dusan Berek
Polymer Institute of the Slovak Academy of Science, Slovakia
Session Introduction
Yingqin Wu
Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, China
Title: Separation the diastereomers of acyclic isoprenoid alkanes by gas chromatography and its geochemical significance
Biography:
Abstract:
The abundant acyclic isoprene alkanes, including norpristane (iC18, 2, 6, 10- tetramethyl tetradecane), pristane (Pr, 2, 6, 10, 14- tetramethylpentadecane), phytane (Ph, 2, 6, 10, 14- tetramethylhexadecane) and their diastereomers were detected and separated by GC-MS/MS in the coal sample of the Junggar Basin. Furthermore, the optimized condition for separation was discussed in terms of column type, length, and column temperature program. The results showed that the separation degree (R) of their diastereomers (e.g. 6(R)10(S)), 6(S)10(S)+6(R)10(R)) of iC18, Pr and Ph reached 0.6, 0.8 and 0.9 respectively. It indicated that the method was versatile, simple, rapid and efficient to separate the diastereomers of acyclic isoprene alkanes. The optimum condition for separation are as follows: GC was fitted with a HP-5 capillary column of 100 m × 0.32 mm × 0.25 μm, Agilent, USA with a He as carrier gas set in a split (10:1) injection mode with an injector temperature of 280°C. The GC oven was held isothermal at 80°C (1 min), programmed to 100°C (1 min) at 5°C min-1, from 100°C to 130°C (5 min) at 0.3°C min-1, from 130°C to 280°C at 5°C min-1, and held for 30 min at 280°C.
Recent Publications
- Evenick J (2016) Evaluating source rock organofacies and paleodepositional environments using bulk rock compositional data and pristane/ phytane ratios. Marine and Petroleum Geology 78:507-515.
- Wu Y, Xia Y, Wang Y and Lei T (2016) The Geochemical characteristics of coals from the junggar basin in Northwest China and the relation of the configuration of pristane with maturity in highly mature and over-mature samples. Oil Gas Sci. Technol. 71(3):35.
- Dawson K, Schaperdoth I, Freeman K and Macalady J (2013) Anaerobic biodegradation of the isoprenoid biomarkers pristane and phytane. Organic Geochemistry 65:118-126.
- Xu G, Shuai Y, Wang P, Zhang D, (2010) Chromatographic separation of pristane and phytane stereoisomers and geochemical significance. Geochemistry 39(5):491-496.
- Peters K, Walters C and Moldowan J (2005) The biomarker guide: biomarkers and isotopes in petroleum system sand earth history. Cambridge: Cambridge University Press, 475-477.
Dusan Berek
Polymer Institute of the Slovak Academy of Science, Slovakia
Title: Retention mechanisms in liquid chromatography of non-charged synthetic macromolecues
Biography:
Dusan Berek, employed at Polymer Institute, Slovak Academy of Sciences in Bratislava. He served as elected member of the Presidium of the Slovak Academy of Sciences, President of the Slovak Chemical Society, Chairman of the Czecho-Slovak and Slovak National Committees of Chemistry for IUPAC. Corresponding member of the Central European Academy of Sciences and Academician of the Learned Society of the Slovakia. Author or co-author of two monographs and 300+ scientific papers in extenso published in refereed periodicals, proceedings and chapters of books, as well as 60+ patents (five of them were licensed) - cited more than 3,000x. Presented over 140 invited plenary, key and main lectures, as well as over 900 regular lectures and poster contributions on symposia and conferences, as well as during lecturing tours to over fourty countries. Elected Slovak scientist of the year 1999“, and Slovak innovator of the year 2002
Abstract:
Liquid chromatography (LC) provides information on both average values and distributions of molecular characteristics of synthetic polymers, their molar mass, chemical structure and physical architecture. Gel permeation (size exclusion) chromatography, GPC/SEC, is commonly employed for determination of polymer molar mass. Its basic retention mechanism is steric exclusion controlled by the changes of conformational entropy of coiled macromolecules entering the pores of the column packing. However, GPC/SEC cannot give quantitative information about polymer when two molecular characteristics mutually depend as in copolymers or in polymer blends. In this case, the entropic retention mechanism is to be coupled with the enthalpic retention mechanisms. The ambition is to suppress molar mass effects so that separation depends only on other molecular characteristic. Yet, one should keep in mind that all enthalpy based processes in a LC column are accompanied with large changes of conformational entropy of macromolecules. The most common enthalpic retention mechanism employed in coupled LC methods is adsorption, the distribution of macromolecules between a volume of its solution and a surface of column packing. It is as a rule controlled by eluent polarity. The appropriate stationary phase is bare silica gel. Another LC retention mechanism is absorption (enthapic partition), the distribution of macromolecules between the volumes of mobile and stationary phase. The practically applicable volume of LC stationary phase is formed by the chemically attached appropriate groups, usually C18 alkyls on a carrier, mainly silica gel. Both adsorption and enthalpic partition retention mechanisms are exploited either isocratically or with a mobile phase gradient. Direct practical application of the third enthalpic retention mechanism, polymer phase separation is rather difficult. Sample is precipitated on the column inlet and then gradually dissolved and eluted. However, solubility of polymers strongly depends on their molar mass so that the molar mass effect is difficult to suppress.
Recent Publications
1.Berek D (2017) Separation of parent homopolymers from nonpolar block copolymers by means of liquid chromatography under limiting conditions of enthalpic interactions. Macromolecular Chemistry Physics 218:137-142.
2.Rollet M, Pelletier B, Berek D, Maria S, Phan T N T and Gigmes D (2016) Separation of parent homopolymers from polystyrene and poly(ethylene oxide) based block copolymers by liquid chromatography under limiting conditions. 3. Study of barrier efficiency according to block copolymer chemical composition. Journal of Chromatography A 1462:63-72.
3. Berek D (2016) Critical assessment of “critical” liquid chromatography of block copolymers. Journal of Separation Science 39(1):93–101.
4. Clementi L A, Meira G R, Berek D, Ronco L I and Vega J R (2015) Molar mass distributions in homopolymer blends from multimodal chromatograms obtained by SEC/GPC with a concentration detector. Polymer Testing 43:58-67.
5. Berek D and Macova E (2015) Liquid chromatography under limiting conditions of desorption 6: Separation of a four-component polymer blend. Journal of Separation Science 38(4):543-549.