Article
Crystallography
Xingyuan Diao, Xiaonan Chen, Shihao Deng, Hongwei Bai
Summary: In this study, trace amounts of epoxy-functionalized small-molecule modifiers were introduced into enantiomeric blends during reactive melt-blending to enhance the formation of stereocomplex-type polylactide (SC-PLA). The results showed that the in situ generation of multi-arm stereo-block PLA copolymers significantly improved SC formation, even with only 0.5 wt% modifiers. The unique copolymers acted as compatibilizers, suppressing the separation of the alternately arranged PLLA/PDLA chain segments in the molten state. Furthermore, the generation of these copolymers did not significantly increase the melt viscosity of the blends, suggesting new opportunities for high-throughput processing of SC-PLA materials.
Article
Chemistry, Applied
Yaowalak Srisuwan, Yodthong Baimark
Summary: This paper reports a study on flexible polymer blends made from PLLA-PEG-PLLA and TPS. The addition of TPS suppressed crystallizability of PLLA and PLLA-PEG-PLLA matrices, while greatly increasing the thermal stability of PLLA-PEG-PLLA. The PEG middle-blocks enhanced phase compatibility between PLLA-PEG-PLLA and TPS, resulting in ductile and flexible blend films.
CARBOHYDRATE POLYMERS
(2022)
Article
Polymer Science
Jeremy L. Swartz, Benjamin R. Elling, Ioannina Castano, Matthew P. Thompson, Daylan T. Sheppard, Nathan C. Gianneschi, William R. Dichtel
Summary: This study introduces a method to enhance the mechanical properties of a miscible blend of thermoplastic polyurethane and polycaprolactone by introducing a copolymer of the two corresponding monomers. The copolymers were generated through a solvent-free, ester/urethane bond-exchange process conducted during the coextrusion of the two polymers. The extrusion conditions affected the extent of bond exchange and the resulting properties of the blend.
Article
Polymer Science
Suyang Dai, Ni Jiang, Zhenbo Ning, Zhihua Gan
Summary: The length of the PDLA block was found to have a significant impact on the degradation behavior of PLLA/4-DL-D blend films.
POLYMER INTERNATIONAL
(2021)
Article
Polymer Science
Prasong Srihanam, Yaowalak Srisuwan, Theeraphol Phromsopha, Apirada Manphae, Yodthong Baimark
Summary: In this study, the phase compatibility and mechanical properties of flexible poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA)/thermoplastic starch (TPS) blends were improved by adding citric acid (CA) as a compatibilizer. The crystallinity of PLLA-PEG-PLLA matrix was suppressed and the thermal stability was enhanced by CA modification of TPS. The compatibility between TPS and PLLA-PEG-PLLA phases was improved, and the blends exhibited increased tensile strength, elongation at break, and Young's modulus with higher CA content.
Article
Chemistry, Multidisciplinary
Rami Hador, Michael Shuster, Vincenzo Venditto, Moshe Kol
Summary: This study proposes a new approach to tolerate stereoerrors in the polymer by crowding them in a stereogradient copolymer. A zirconium complex of an amine tris(phenolate) ligand is used as a catalyst for the ring opening polymerization of meso-lactide at room temperature, and stereogradient copolymers are formed in the polymerization of mixtures of meso-lactide/L-lactide at 180 degrees C. These stereogradient copolymers exhibit enhanced crystallinities compared to stereorandom copolymers obtained with tin octanoate.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Polymer Science
Lidong Feng, Xinchao Bian, Gao Li, Xuesi Chen
Summary: By investigating the thermal properties, morphology, and thermal stability of PLLA/PDLA blends, a new stereoamorphous mesophase (sam-PLA) structure was discovered, and the relationship between different phases in the PLLA/PDLA blends was explored.
Article
Polymer Science
Lidong Feng, Xinchao Bian, Gao Li, Xuesi Chen
Summary: The study shows that the compatibility between PLLA and PLDLA-m decreases as the L-lactate unit content in PLDLA-m decreases, impacting the crystallization and compatibility of the blends.
Article
Biochemistry & Molecular Biology
Fen Ma, Chenguang Jiang, Wenyuan Xie, Defeng Wu
Summary: Using polysaccharide nanocrystals, such as chitin nanocrystals, as nanofillers for biodegradable aliphatic polymers is an attractive method for developing fully degradable nanocomposites. The incorporation of chitin nanocrystals in poly(L-lactide)/poly(D-lactide) blends promotes the formation of stereocomplex crystallites and accelerates overall crystallization kinetics. The nanocomposites exhibit higher stereocomplex crystallization temperatures and lower activation energy compared to the blend. However, the presence of chitin nanocrystals reduces the fraction of stereocomplex crystallites due to the nucleation effect, despite an increased rate of homocrystallization. This study provides valuable information for the use of chitin nanocrystals as nucleators for polylactide stereocomplexes.
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
(2023)
Article
Polymer Science
Lei Hua, Xiaodong Wang
Summary: New biodegradable aliphatic PLLA-PBA-PLLA copolymers with different PLLA block lengths showed different structures and crystallization behaviors of PBA-mid, which were studied using various analytical techniques.
Article
Polymer Science
Moritz Meier-Merziger, Marcel Fickenscher, Frank Hartmann, Bjoern Kuttich, Tobias Kraus, Markus Gallei, Holger Frey
Summary: Bifunctional initiators were used to synthesize complex triblock copolymer structures in carbanionic polymerization. Isoprene was polymerized using 1,3-bis(1-phenylethenyl)benzene (PEB), resulting in a high content of 93% 1,4-PI units. Hydroxyl groups were then introduced simultaneously in the alpha- and omega-position using end-functionalization of the living anionic di-lithiated polyisoprene (PI) chains with 1,2-isopropylidene glyceryl glycidyl ether (IGG) and subsequent acidic deprotection. The resulting hexa-hydroxy functional PI-macroinitiators were used to initiate l-lactide (LLA) polymerization, leading to the formation of super-H-shaped (PLLA)(3)-b-PI-b-(PLLA)(3) triblock structures with narrow molecular weight distributions.
Article
Polymer Science
Zhuoxin Zhuang, Tiantian Li, Zhenbo Ning, Ni Jiang, Zhihua Gan
Summary: The synthesis of lignin-grafted-poly (o-lactide) (LGPD) with different poly(o-lactide) (PDLA) block lengths improved the crystallization, mechanical properties, and UV-absorbance properties of poly(L-lactide) (PLLA). The longer PDLA block length in LGPD led to faster crystallization rates and broader melting ranges of stereocomplex (SC) crystallites. Moreover, the LGPD blends showed improved tensile strength and UV-absorbance properties compared to neat PLLA.
EUROPEAN POLYMER JOURNAL
(2022)
Article
Chemistry, Physical
Joshua Moncada, Mark D. D. Dadmun
Summary: Polymeric materials, such as PET, are widely used but generate a large quantity of waste. Chemical recycling of PET is of interest, but methods for complete depolymerization are time- and energy-intensive. This study investigates the depolymerization of PET and proposes a method to capture telechelic oligomers as reactants, which can be used to produce value-added goods. The reaction conditions, such as temperature and catalyst loading, affect the product chain structure and yield. The results provide crucial insight into producing target telechelic oligomers of PET.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Polymer Science
Mingmei Mi, Jing Yu, Xiangyang Li, Min Zhou, Hao Xiu, Hongwei Bai
Summary: Stereocomplex-type polylactide (SC-PLA) is a promising engineering bio-plastic that enhances heat resistance and hydrolytic stability through the crystallization between poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA). By using dibenzoylhydrazide compound as a nucleating agent, the SC crystallization of PLLA/PDLA blends is promoted, leading to smaller crystal size.
Article
Polymer Science
Prasong Srihanam, Wiriya Thongsomboon, Yodthong Baimark
Summary: The aim of this study was to modify PLLA-b-PEG-b-PLLA copolymer using low-cost CaCO3 filler to improve its material properties. The addition of CaCO3 enhanced the crystallinity and thermal stability of PLLA-b-PEG-b-PLLA matrix. SEM analysis showed stronger interfacial adhesion between PLLA-b-PEG-b-PLLA and CaCO3 compared to PLLA and CaCO3. Tensile testing revealed increased stress and modulus for PLLA-b-PEG-b-PLLA matrix with CaCO3, while these properties significantly decreased for PLLA matrix. Therefore, CaCO3 shows promise as an inexpensive filler for improving PLLA-b-PEG-b-PLLA bioplastics.
Article
Polymer Science
Mark P. F. Pepels, Rob G. Kleijnen, Johannes G. P. Goossens, Anne B. Spoelstra, Renate Tandler, Hans Martens, Maria Soliman, Rob Duchateau
Article
Chemistry, Multidisciplinary
Manfred Schmid, Rob Kleijnen, Marc Vetterli, Konrad Wegener
APPLIED SCIENCES-BASEL
(2017)
Article
Chemistry, Multidisciplinary
Rob G. Kleijnen, Manfred Schmid, Konrad Wegener
APPLIED SCIENCES-BASEL
(2019)
Article
Engineering, Manufacturing
Francesco Sillani, Rob G. Kleijnen, Marc Vetterli, Manfred Schmid, Konrad Wegener
ADDITIVE MANUFACTURING
(2019)
Proceedings Paper
Physics, Applied
R. G. Kleijnen, J. P. W. Sesseg, M. Schmid, K. Wegener
PROCEEDINGS OF PPS-32: THE 32ND INTERNATIONAL CONFERENCE OF THE POLYMER PROCESSING SOCIETY
(2017)
Proceedings Paper
Physics, Applied
R. G. Kleijnen, M. Schmid, K. Wegener
PROCEEDINGS OF THE REGIONAL CONFERENCE GRAZ 2015 - POLYMER PROCESSING SOCIETY PPS: CONFERENCE PAPERS
(2016)