Kazuki Fukushima

Abstract Polymeric materials prepared from renewable natural resources are now being accepted as “bio‐based polymers”, because they are superior to the conventional petroleum‐based polymers in reducing the emission of carbon dioxide. Among them, poly( L ‐lactide) (PLLA) prepared by fermentation and polymerization is paid an immediate attention. Although PLLA exhibits a broad range of physico‐chemical properties, its thermal and mechanical properties are somewhat poorer for use as ordinary struct

Aliphatic polycarbonates have drawn attention as biodegradable polymers that can be applied to a broad range of resorbable medical devices. In particular, poly(trimethylene carbonate) (PTMC), its copolymers, and its derivatives are currently studied due to their unique degradation characteristics that are different from those of aliphatic polyesters. Furthermore, their flexible and hydrophobic nature has driven the application of PTMC-based polymers to soft tissue regeneration and drug delivery.

Abstract We describe the organocatalytic depolymerization of poly(ethylene terephthalate) (PET), using a commercially available guanidine catalyst, 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD). Postconsumer PET beverage bottles were used and processed with 1.0 mol % (0.7 wt %) of TBD and excess amount of ethylene glycol (EG) at 190 °C for 3.5 hours under atmospheric pressure to give bis(2‐hydroxyethyl) terephthalate (BHET) in 78% isolated yield. The catalyst efficiency was comparable to other metal

We report the effective organocatalysis of the aminolytic depolymerization of waste poly(ethylene terephthalate) (PET) using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) producing a broad range of crystalline terephthalamides. This diverse set of monomers possesses great potential as building blocks for high performance materials with desirable thermal and mechanical properties deriving from the terephthalic moiety and amide hydrogen bonding. Further, a computational study established mechanistic i

Abstract Simultaneous solid‐state polycondensation (SSP) of the powdery prepolymers of poly( L ‐lactic acid) (PLLA) and poly( D ‐lactic acid) (PDLA) can produce entire stereocomplexed poly(lactic acid)s (sc‐PLA) with high molecular weight and can be an alternative synthetic route to sc‐PLA. Ordinary melt polycondensations of L ‐ and D ‐lactic acids gave the PLLA and PDLA prepolymers having medium molecular weight which were pulverized for blending in 1:1 ratio. The resultant powder blends were t

Stereoblock poly(lactic acid) (sb-PLA) is incorporated into a 1:1 polymer blend system of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) that has a high molecular weight to study its addition effect on the stereocomplex (sc) formation of PLLA and PDLA. The ternary polymer blend films are first prepared by casting polymer solutions of sb-PLA, PLLA, and PDLA with different compositions. Upon increasing the content of sb-PLA in the blend films the sc crystallization is driven to a higher

Stereoblock poly(lactic acid) consisting of D- and L-lactate stereosequences can be successfully synthesized by solid-state polycondensation of a 1:1 mixture of poly(L-lactic acid) and poly(D-lactic acid). In the first step, melt-polycondensation of L- and D-lactic acids is conducted to synthesize poly(L-lactic acid) and poly(D-lactic acid) with a medium-molecular-weight, respectively. In the next step, these poly(L-lactic acid) and poly(D-lactic acid) are melt-blended in 1:1 ratio to allow form

D-Lactic acid was synthesized by the fermentation of rice starch using microorganisms. Two species: Lactobacillus delbrueckii and Sporolactobacillus inulinus were found to be active in producing D-lactic acid of high optical purity after an intensive screening test for D-lactic acid bacteria using glucose as substrate. Rice powder used as the starch source was hydrolyzed with a combination of enzymes: alpha-amylase, beta-amylase, and pullulanase to obtain rice saccharificate consisting of maltos

Abstract This article describes studies on the catalytic activity of several nitrogen‐based organic catalysts for the depolymerization of poly(ethylene terephthalate) (PET), in which a few cyclic amidines work more effectively than a potent, bifunctional guanidine‐based catalyst 1,5,7‐triazabicyclo‐[4,4,0]‐dec‐5‐ene (TBD) in the presence of short chain diols that play a role in activation of carbonyl groups through hydrogen bonding. Further studies prove that the catalytic efficiency at the abov

Biocompatible amphiphilic block copolymers comprised of poly(ethylene glycol) (PEG) as the hydrophilic component and a poly(methylcarboxytrimethylene carbonate) (PMTC) as a hydrophobic backbone having either poly(L-lactide) (L-PLA) or poly(D-lactide) (D-PLA) branches were prepared by organocatalytic ring-opening polymerization (ROP). The polycarbonate backbone was prepared by copolymerization of two different MTC-type monomers (MTCs) including a tetrahydropyranyloxy protected hydroxyl group, a m

With the increased prevalence of antibiotic-resistant infections, there is an urgent need for innovative antimicrobial treatments. One such area being actively explored is the use of self-assembling cationic polymers. This relatively new class of materials was inspired by biologically pervasive cationic host defense peptides. The antimicrobial action of both the synthetic polymers and naturally occurring peptides is believed to be complemented by their three-dimensional structure. In an effort t

Stereoblock poly(lactic acid)s (sb-PLA) consisting of different ratios of d- and l-sequences were synthesized by a process involving solid-state polycondensation (SSP) of polymer blends of poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) of medium molecular weight. Both PLLA and PDLA prepolymers were first prepared by direct melt-polycondensation of l- and d-lactic acids, respectively. These prepolymers were melt-blended in different ratios where their respective partial stereocomplexat

ADVERTISEMENT RETURN TO ISSUEPREVEditorialNEXTADDITION / CORRECTIONThis article has been corrected. View the notice.Organocatalysis: A Paradigm Shift in the Synthesis of Aliphatic Polyesters and PolycarbonatesKazuki Fukushima*Kazuki Fukushima*Email: [email protected]More by Kazuki Fukushimahttp://orcid.org/0000-0002-6980-9663 and Kyoko Nozaki*Kyoko Nozaki*Email: [email protected]More by Kyoko Nozakihttp://orcid.org/0000-0002-0321-5299Cite this: Macromolecules 2020, 53, 13, 5018–5022Publication D

Abstract Stereoblock poly(lactic acid) (sb‐PLA), consisting of poly(L‐lactic acid) (PLLA) and poly(D‐lactic acid) (PDLA) in a blocky sequence, can successfully be synthesized by solid‐state polycondensation of a stereocomplexed mixture of PLLA and PDLA. First, the melt polyconden‐sation of L‐ and D‐lactic acids is conducted to obtain PLLA and PDLA with medium molecular weights. Then, both polymers are melt‐blended to easily form the stereocomplex. The resulting stereocomplexed mixture (melt‐blen