Synthesis and characterization of macrocyclic vinyl aromatic polymers

Hogen‐Esch, Thieo E.

doi:10.1002/pola.21331

Cited by 54 publications

(81 citation statements)

References 62 publications

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“…Since then, a weak but steady flow of publications dealing with cyclic polymers has continued. Meanwhile, several review articles dealing with syntheses and properties of circular polymers have appeared, but these articles do not clearly distinguish between synthetic methods and synthetic strategies 14–19. Therefore, this differentiation should be presented at this point before any discussion of new theories and experimental results.…”

Section: Introductionmentioning

confidence: 99%

Distinct topography of erosion and new bone formation in achilles tendon enthesitis: Implications for understanding the link between inflammation and bone formation in spondylarthritis

McGonagle¹,

Wakefield²,

Tan³

et al. 2008

Arthritis & Rheumatism

112

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Objective. This study combined ultrasonography of the Achilles tendon enthesis at different stages of spondylarthritis (SpA) with microanatomic studies of normal cadaveric entheses, with the aim of exploring the relationship between bone erosion and new bone formation in enthesitis.Methods. Thirty-seven patients with SpA and Achilles tendon enthesitis (20 with early SpA and 17 with chronic SpA) and 10 normal control subjects underwent ultrasound scanning. The presence of bone erosion and spur formation was recorded at 3 sites: the proximal and distal halves of the enthesis and the adjacent calcaneal superior tuberosity. Parallel histologic analysis was performed on cadaveric Achilles tendon entheses to determine whether regional variations in bone density and trabecular architecture in relation to fibrocartilage distribution are related to disease patterns.Results. Bone erosion in patients with early SpA occurred at either the proximal insertion or the superior tuberosity (11 of 20 patients; P < 0.001 versus distal enthesis). Very small spurs, which were present almost exclusively at the distal enthesis, were evident in patients with early SpA and in normal control subjects. However, large spurs were evident distally only in patients with chronic SpA (9 of 17 patients, compared with none of 20 patients with early SpA; P < 0.0001). Histologic studies showed that aged normal individuals had small spurs at the corresponding location. The bone-to-marrow ratio was also significantly lower in the regions prone to erosions (P < 0.05).Conclusion. Bone erosion in association with Achilles tendon enthesitis in SpA is anatomically uncoupled from bone formation-the 2 processes are topographically and temporally distinct. We thus conclude that disease patterns in SpA are related to normal enthesis structure and biomechanics.

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Section: Introductionmentioning

confidence: 99%

Distinct topography of erosion and new bone formation in achilles tendon enthesitis: Implications for understanding the link between inflammation and bone formation in spondylarthritis

McGonagle¹,

Wakefield²,

Tan³

et al. 2008

Arthritis & Rheumatism

112

View full text Add to dashboard Cite

show abstract

“…Meanwhile, several review articles dealing with syntheses and properties of circular polymers have appeared, but these articles do not clearly distinguish between synthetic methods and synthetic strategies. [14][15][16][17][18][19] Therefore, this differentiation should be presented at this point before any discussion of new theories and experimental results.…”

Section: P 149)mentioning

confidence: 99%

Cyclic polymers: Synthetic strategies and physical properties

Kricheldorf

2009

J. Polym. Sci. A Polym. Chem.

394

442

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Syntheses of cyclic polymers including cyclic homopolymers, cyclic block copolymers, sun-shaped polymers, and tadpole polymers are discussed on the basis of a differentiation between synthetic methods and synthetic strategies (e.g., polycondensation, ring-ring equilibration, or ring-expansion polymerization). Furthermore, all synthetic methods are classified as kinetically or thermodynamically controlled reactions. Characteristic properties of cyclic polymers such as smaller hydrodynamic volume, lower melt viscosities, and higher thermostabilities are compared to the properties of their linear counterparts. Furthermore, the nanophase separation of cyclic diblock copolymers is discussed.

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“…The hydrodynamic volume ratio or <G> value equals 0.77, which is in good agreement with precedent literature data. 53,54,55 Noteworthy is that a small fraction of ca. 5-7 % of intermolecular reaction product was observed at higher MWs, which corresponds to byproduct polymers lacking the TLa end groups (see above).…”

Section: Synthesis and Characterization Of The Cyclic Poly(styrene) (mentioning

confidence: 99%

Straightforward synthesis of functionalized cyclic polymers in high yield via RAFT and thiolactone–disulfide chemistry

et al. 2013

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An efficient synthetic pathway toward cyclic polymers based on the combination of thiolactone and disulfide chemistry, has been developed. First, heterotelechelic linear polystyrene (PS) containing an α-thiolactone (TLa) and an ω-dithiobenzoate group was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, employing a newly designed TLa-bearing chain transfer agent. The subsequent reaction of this heterotelechelic polymer with an amine, which acts as a nucleophile for both the TLa and dithiobenzoate units, generated the α,ω-thiol-telechelic PS under ambient conditions without the need for any catalyst or other additive. The arrangement of thiols under a high dilution afforded single cyclic c-PSs through an oxidative disulfide linkage. The cyclic polystyrene (c-PS) disulfide ring formation was evidenced by SEC, MALDI-TOF MS and 1 H-NMR characterization. Moreover, we demonstrated a controlled ring opening via either disulfide reduction or thiol/disulfide exchange to enable easy and clean topology transformation. Furthermore, to illustrate the broad utility of this synthetic methodology, different amines including functional ones were employed, allowing for the one-step preparation of functionalized cyclic polymers with high yields.

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Synthesis and characterization of macrocyclic vinyl aromatic polymers

Cited by 54 publications

References 62 publications

Distinct topography of erosion and new bone formation in achilles tendon enthesitis: Implications for understanding the link between inflammation and bone formation in spondylarthritis

Distinct topography of erosion and new bone formation in achilles tendon enthesitis: Implications for understanding the link between inflammation and bone formation in spondylarthritis

Cyclic polymers: Synthetic strategies and physical properties

Straightforward synthesis of functionalized cyclic polymers in high yield via RAFT and thiolactone–disulfide chemistry

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